scala.collection.mutable.ListBuffer

final class ListBuffer[A] extends AbstractBuffer[A] with Buffer[A] with GenericTraversableTemplate[A, ListBuffer] with BufferLike[A, ListBuffer[A]] with ReusableBuilder[A, immutable.List[A]] with SeqForwarder[A] with Serializable

A Buffer implementation backed by a list. It provides constant time prepend and append. Most other operations are linear.

Type Members

type Self = ListBuffer[A]

The type implementing this traversable

  • Attributes
    • protected[this]
  • Definition Classes
    • TraversableLike

class WithFilter extends FilterMonadic[A, Repr]

A class supporting filtered operations. Instances of this class are returned by method withFilter .

  • Definition Classes
    • TraversableLike

Value Members From scala.Function1

def compose[A](g: (A) ⇒ Int): (A) ⇒ A

Composes two instances of Function1 in a new Function1, with this function applied last.

  • A
    • the type to which function g can be applied
  • g
    • a function A => T1
  • returns
    • a new function f such that f(x) == apply(g(x))
  • Definition Classes
    • Function1
  • Annotations
    • @ unspecialized ()

(defined at scala.Function1)

Value Members From scala.PartialFunction

def andThen[C](k: (A) ⇒ C): PartialFunction[Int, C]

Composes this partial function with a transformation function that gets applied to results of this partial function.

  • C
    • the result type of the transformation function.
  • k
    • the transformation function
  • returns
    • a partial function with the same domain as this partial function, which maps arguments x to k(this(x)) .
  • Definition Classes
    • PartialFunction → Function1

(defined at scala.PartialFunction)

def applyOrElse[A1 <: Int, B1 >: A](x: A1, default: (A1) ⇒ B1): B1

Applies this partial function to the given argument when it is contained in the function domain. Applies fallback function where this partial function is not defined.

Note that expression pf.applyOrElse(x, default) is equivalent to

if(pf isDefinedAt x) pf(x) else default(x)

except that applyOrElse method can be implemented more efficiently. For all partial function literals the compiler generates an applyOrElse implementation which avoids double evaluation of pattern matchers and guards. This makes applyOrElse the basis for the efficient implementation for many operations and scenarios, such as:

  • combining partial functions into orElse / andThen chains does not lead to excessive apply / isDefinedAt evaluation
  • lift and unlift do not evaluate source functions twice on each invocation
  • runWith allows efficient imperative-style combining of partial functions with conditionally applied actions

For non-literal partial function classes with nontrivial isDefinedAt method it is recommended to override applyOrElse with custom implementation that avoids double isDefinedAt evaluation. This may result in better performance and more predictable behavior w.r.t. side effects.

  • x
    • the function argument
  • default
    • the fallback function
  • returns
    • the result of this function or fallback function application.
  • Definition Classes
    • PartialFunction
  • Since
    • 2.10

(defined at scala.PartialFunction)

def lift: (Int) ⇒ Option[A]

Turns this partial function into a plain function returning an Option result.

  • returns
    • a function that takes an argument x to Some(this(x)) if this is defined for x , and to None otherwise.
  • Definition Classes
    • PartialFunction
  • See also
    • Function.unlift

(defined at scala.PartialFunction)

def orElse[A1 <: Int, B1 >: A](that: PartialFunction[A1, B1]): PartialFunction[A1, B1]

Composes this partial function with a fallback partial function which gets applied where this partial function is not defined.

  • A1
    • the argument type of the fallback function
  • B1
    • the result type of the fallback function
  • that
    • the fallback function
  • returns
    • a partial function which has as domain the union of the domains of this partial function and that . The resulting partial function takes x to this(x) where this is defined, and to that(x) where it is not.
  • Definition Classes
    • PartialFunction

(defined at scala.PartialFunction)

def runWith[U](action: (A) ⇒ U): (Int) ⇒ Boolean

Composes this partial function with an action function which gets applied to results of this partial function. The action function is invoked only for its side effects; its result is ignored.

Note that expression pf.runWith(action)(x) is equivalent to

if(pf isDefinedAt x) { action(pf(x)); true } else false

except that runWith is implemented via applyOrElse and thus potentially more efficient. Using runWith avoids double evaluation of pattern matchers and guards for partial function literals.

  • action
    • the action function
  • returns
    • a function which maps arguments x to isDefinedAt(x) . The resulting function runs action(this(x)) where this is defined.
  • Definition Classes
    • PartialFunction
  • Since
    • 2.10
  • See also
    • applyOrElse .

(defined at scala.PartialFunction)

Value Members From scala.collection.IterableLike

def canEqual(that: Any): Boolean

Method called from equality methods, so that user-defined subclasses can refuse to be equal to other collections of the same kind.

  • that
    • The object with which this iterable collection should be compared
  • returns
    • true , if this iterable collection can possibly equal that , false otherwise. The test takes into consideration only the run-time types of objects but ignores their elements.
  • Definition Classes
    • IterableLike → Equals

(defined at scala.collection.IterableLike)

def drop(n: Int): ListBuffer[A]

Selects all elements except first n ones.

Note: might return different results for different runs, unless the underlying collection type is ordered.

  • n
    • the number of elements to drop from this iterable collection.
  • returns
    • a iterable collection consisting of all elements of this iterable collection except the first n ones, or else the empty iterable collection, if this iterable collection has less than n elements.
  • Definition Classes
    • IterableLike → TraversableLike → GenTraversableLike

(defined at scala.collection.IterableLike)

def dropRight(n: Int): ListBuffer[A]

Selects all elements except last n ones.

Note: might return different results for different runs, unless the underlying collection type is ordered.

  • n
    • The number of elements to take
  • returns
    • a iterable collection consisting of all elements of this iterable collection except the last n ones, or else the empty iterable collection, if this iterable collection has less than n elements.
  • Definition Classes
    • IterableLike

(defined at scala.collection.IterableLike)

def grouped(size: Int): Iterator[ListBuffer[A]]

Partitions elements in fixed size iterable collections.

  • size
    • the number of elements per group
  • returns
    • An iterator producing iterable collections of size size , except the last will be less than size size if the elements don’t divide evenly.
  • Definition Classes
    • IterableLike
  • See also
    • scala.collection.Iterator, method grouped

(defined at scala.collection.IterableLike)

def slice(from: Int, until: Int): ListBuffer[A]

Selects an interval of elements. The returned collection is made up of all elements x which satisfy the invariant:

from <= indexOf(x) < until

Note: might return different results for different runs, unless the underlying collection type is ordered.

  • returns
    • a iterable collection containing the elements greater than or equal to index from extending up to (but not including) index until of this iterable collection.
  • Definition Classes
    • IterableLike → TraversableLike → GenTraversableLike

(defined at scala.collection.IterableLike)

def sliding(size: Int): Iterator[ListBuffer[A]]

Groups elements in fixed size blocks by passing a “sliding window” over them (as opposed to partitioning them, as is done in grouped.) “Sliding window” step is 1 by default.

  • size
    • the number of elements per group
  • returns
    • An iterator producing iterable collections of size size , except the last and the only element will be truncated if there are fewer elements than size.
  • Definition Classes
    • IterableLike
  • See also
    • scala.collection.Iterator, method sliding

(defined at scala.collection.IterableLike)

def sliding(size: Int, step: Int): Iterator[ListBuffer[A]]

Groups elements in fixed size blocks by passing a “sliding window” over them (as opposed to partitioning them, as is done in grouped.)

  • size
    • the number of elements per group
  • step
    • the distance between the first elements of successive groups
  • returns
    • An iterator producing iterable collections of size size , except the last and the only element will be truncated if there are fewer elements than size.
  • Definition Classes
    • IterableLike
  • See also
    • scala.collection.Iterator, method sliding

(defined at scala.collection.IterableLike)

def take(n: Int): ListBuffer[A]

Selects first n elements.

Note: might return different results for different runs, unless the underlying collection type is ordered.

  • n
    • the number of elements to take from this iterable collection.
  • returns
    • a iterable collection consisting only of the first n elements of this iterable collection, or else the whole iterable collection, if it has less than n elements.
  • Definition Classes
    • IterableLike → TraversableLike → GenTraversableLike

(defined at scala.collection.IterableLike)

def takeRight(n: Int): ListBuffer[A]

Selects last n elements.

Note: might return different results for different runs, unless the underlying collection type is ordered.

  • n
    • the number of elements to take
  • returns
    • a iterable collection consisting only of the last n elements of this iterable collection, or else the whole iterable collection, if it has less than n elements.
  • Definition Classes
    • IterableLike

(defined at scala.collection.IterableLike)

def takeWhile(p: (A) ⇒ Boolean): ListBuffer[A]

Takes longest prefix of elements that satisfy a predicate.

Note: might return different results for different runs, unless the underlying collection type is ordered.

  • returns
    • the longest prefix of this iterable collection whose elements all satisfy the predicate p .
  • Definition Classes
    • IterableLike → TraversableLike → GenTraversableLike

(defined at scala.collection.IterableLike)

def zipAll[B, A1 >: A, That](that: GenIterable[B], thisElem: A1, thatElem: B)(implicit bf: CanBuildFrom[ListBuffer[A], (A1, B), That]): That

[use case]

Returns a list buffer formed from this list buffer and another iterable collection by combining corresponding elements in pairs. If one of the two collections is shorter than the other, placeholder elements are used to extend the shorter collection to the length of the longer.

  • B
    • the type of the second half of the returned pairs
  • that
    • The iterable providing the second half of each result pair
  • thisElem
    • the element to be used to fill up the result if this list buffer is shorter than that .
  • thatElem
    • the element to be used to fill up the result if that is shorter than this list buffer.
  • returns
    • a new list buffer containing pairs consisting of corresponding elements of this list buffer and that . The length of the returned collection is the maximum of the lengths of this list buffer and that . If this list buffer is shorter than that , thisElem values are used to pad the result. If that is shorter than this list buffer, thatElem values are used to pad the result.
  • Definition Classes
    • IterableLike → GenIterableLike

(defined at scala.collection.IterableLike)

def zipWithIndex[A1 >: A, That](implicit bf: CanBuildFrom[ListBuffer[A], (A1, Int), That]): That

[use case]

Zips this list buffer with its indices.

  • returns
    • A new list buffer containing pairs consisting of all elements of this list buffer paired with their index. Indices start at 0 .
  • Definition Classes
    • IterableLike → GenIterableLike

Example:

List("a", "b", "c").zipWithIndex = List(("a", 0), ("b", 1), ("c", 2))

(defined at scala.collection.IterableLike)

def zip[A1 >: A, B, That](that: GenIterable[B])(implicit bf: CanBuildFrom[ListBuffer[A], (A1, B), That]): That

[use case]

Returns a list buffer formed from this list buffer and another iterable collection by combining corresponding elements in pairs. If one of the two collections is longer than the other, its remaining elements are ignored.

  • B
    • the type of the second half of the returned pairs
  • that
    • The iterable providing the second half of each result pair
  • returns
    • a new list buffer containing pairs consisting of corresponding elements of this list buffer and that . The length of the returned collection is the minimum of the lengths of this list buffer and that .
  • Definition Classes
    • IterableLike → GenIterableLike

(defined at scala.collection.IterableLike)

Value Members From scala.collection.Parallelizable

def par: ParSeq[A]

Returns a parallel implementation of this collection.

For most collection types, this method creates a new parallel collection by copying all the elements. For these collection, par takes linear time. Mutable collections in this category do not produce a mutable parallel collection that has the same underlying dataset, so changes in one collection will not be reflected in the other one.

Specific collections (e.g. ParArray or mutable.ParHashMap ) override this default behaviour by creating a parallel collection which shares the same underlying dataset. For these collections, par takes constant or sublinear time.

All parallel collections return a reference to themselves.

  • returns
    • a parallel implementation of this collection
  • Definition Classes
    • Parallelizable

(defined at scala.collection.Parallelizable)

Value Members From scala.collection.SeqLike

def +:[B >: A, That](elem: B)(implicit bf: CanBuildFrom[ListBuffer[A], B, That]): That

[use case]

A copy of the list buffer with an element prepended.

Note that :-ending operators are right associative (see example). A mnemonic for +: vs. :+ is: the COLon goes on the COLlection side.

Also, the original list buffer is not modified, so you will want to capture the result.

Example:

scala> val x = List(1)
x: List[Int] = List(1)

scala> val y = 2 +: x
y: List[Int] = List(2, 1)

scala> println(x)
List(1)
  • elem
    • the prepended element
  • returns
    • a new list buffer consisting of elem followed by all elements of this list buffer.
  • Definition Classes
    • SeqLike → GenSeqLike

(defined at scala.collection.SeqLike)

def :+[B >: A, That](elem: B)(implicit bf: CanBuildFrom[ListBuffer[A], B, That]): That

[use case]

A copy of this list buffer with an element appended.

A mnemonic for +: vs. :+ is: the COLon goes on the COLlection side.

Example:

scala> val a = List(1)
a: List[Int] = List(1)

scala> val b = a :+ 2
b: List[Int] = List(1, 2)

scala> println(a)
List(1)
  • elem
    • the appended element
  • returns
    • a new list buffer consisting of all elements of this list buffer followed by elem .
  • Definition Classes
    • SeqLike → GenSeqLike

(defined at scala.collection.SeqLike)

def combinations(n: Int): Iterator[ListBuffer[A]]

Iterates over combinations. A combination of length n is a subsequence of the original sequence, with the elements taken in order. Thus, "xy" and "yy" are both length-2 combinations of "xyy" , but "yx" is not. If there is more than one way to generate the same subsequence, only one will be returned.

For example, "xyyy" has three different ways to generate "xy" depending on whether the first, second, or third "y" is selected. However, since all are identical, only one will be chosen. Which of the three will be taken is an implementation detail that is not defined.

  • returns
    • An Iterator which traverses the possible n-element combinations of this sequence.
  • Definition Classes
    • SeqLike

Example:

"abbbc".combinations(2) = Iterator(ab, ac, bb, bc)

(defined at scala.collection.SeqLike)

def diff[B >: A](that: GenSeq[B]): ListBuffer[A]

[use case]

Computes the multiset difference between this list buffer and another sequence.

  • that
    • the sequence of elements to remove
  • returns
    • a new list buffer which contains all elements of this list buffer except some of occurrences of elements that also appear in that . If an element value x appears n times in that , then the first n occurrences of x will not form part of the result, but any following occurrences will.
  • Definition Classes
    • SeqLike → GenSeqLike

(defined at scala.collection.SeqLike)

def distinct: ListBuffer[A]

Builds a new sequence from this sequence without any duplicate elements.

Note: will not terminate for infinite-sized collections.

  • returns
    • A new sequence which contains the first occurrence of every element of this sequence.
  • Definition Classes
    • SeqLike → GenSeqLike

(defined at scala.collection.SeqLike)

def intersect[B >: A](that: GenSeq[B]): ListBuffer[A]

[use case]

Computes the multiset intersection between this list buffer and another sequence.

  • that
    • the sequence of elements to intersect with.
  • returns
    • a new list buffer which contains all elements of this list buffer which also appear in that . If an element value x appears n times in that , then the first n occurrences of x will be retained in the result, but any following occurrences will be omitted.
  • Definition Classes
    • SeqLike → GenSeqLike

(defined at scala.collection.SeqLike)

def padTo[B >: A, That](len: Int, elem: B)(implicit bf: CanBuildFrom[ListBuffer[A], B, That]): That

[use case]

A copy of this list buffer with an element value appended until a given target length is reached.

  • len
    • the target length
  • elem
    • the padding value
  • returns
    • a new list buffer consisting of all elements of this list buffer followed by the minimal number of occurrences of elem so that the resulting list buffer has a length of at least len .
  • Definition Classes
    • SeqLike → GenSeqLike

(defined at scala.collection.SeqLike)

def patch[B >: A, That](from: Int, patch: GenSeq[B], replaced: Int)(implicit bf: CanBuildFrom[ListBuffer[A], B, That]): That

[use case]

Produces a new list buffer where a slice of elements in this list buffer is replaced by another sequence.

  • from
    • the index of the first replaced element
  • replaced
    • the number of elements to drop in the original list buffer
  • returns
    • a new list buffer consisting of all elements of this list buffer except that replaced elements starting from from are replaced by patch .
  • Definition Classes
    • SeqLike → GenSeqLike

(defined at scala.collection.SeqLike)

def permutations: Iterator[ListBuffer[A]]

Iterates over distinct permutations.

  • returns
    • An Iterator which traverses the distinct permutations of this sequence.
  • Definition Classes
    • SeqLike

Example:

"abb".permutations = Iterator(abb, bab, bba)

(defined at scala.collection.SeqLike)

def reverse: ListBuffer[A]

Returns new sequence with elements in reversed order.

Note: will not terminate for infinite-sized collections.

  • returns
    • A new sequence with all elements of this sequence in reversed order.
  • Definition Classes
    • SeqLike → GenSeqLike

(defined at scala.collection.SeqLike)

def reverseMap[B, That](f: (A) ⇒ B)(implicit bf: CanBuildFrom[ListBuffer[A], B, That]): That

[use case]

Builds a new collection by applying a function to all elements of this list buffer and collecting the results in reversed order.

Note: xs.reverseMap(f) is the same as xs.reverse.map(f) but might be more efficient.

  • B
    • the element type of the returned collection.
  • f
    • the function to apply to each element.
  • returns
    • a new list buffer resulting from applying the given function f to each element of this list buffer and collecting the results in reversed order.
  • Definition Classes
    • SeqLike → GenSeqLike

(defined at scala.collection.SeqLike)

def sortBy[B](f: (A) ⇒ B)(implicit ord: math.Ordering[B]): ListBuffer[A]

Sorts this Seq according to the Ordering which results from transforming an implicitly given Ordering with a transformation function.

  • B
    • the target type of the transformation f , and the type where the ordering ord is defined.
  • f
    • the transformation function mapping elements to some other domain B .
  • ord
    • the ordering assumed on domain B .
  • returns
    • a sequence consisting of the elements of this sequence sorted according to the ordering where x < y if ord.lt(f(x), f(y)) .
  • Definition Classes
    • SeqLike
  • See also
    • scala.math.Ordering Note: will not terminate for infinite-sized collections.

Example:

val words = "The quick brown fox jumped over the lazy dog".split(' ')
// this works because scala.Ordering will implicitly provide an Ordering[Tuple2[Int, Char]]
words.sortBy(x => (x.length, x.head))
res0: Array[String] = Array(The, dog, fox, the, lazy, over, brown, quick, jumped)

(defined at scala.collection.SeqLike)

def sortWith(lt: (A, A) ⇒ Boolean): ListBuffer[A]

Sorts this sequence according to a comparison function.

Note: will not terminate for infinite-sized collections.

The sort is stable. That is, elements that are equal (as determined by lt ) appear in the same order in the sorted sequence as in the original.

  • lt
    • the comparison function which tests whether its first argument precedes its second argument in the desired ordering.
  • returns
    • a sequence consisting of the elements of this sequence sorted according to the comparison function lt .
  • Definition Classes
    • SeqLike

Example:

List("Steve", "Tom", "John", "Bob").sortWith(_.compareTo(_) < 0) =
List("Bob", "John", "Steve", "Tom")

(defined at scala.collection.SeqLike)

def sorted[B >: A](implicit ord: math.Ordering[B]): ListBuffer[A]

Sorts this sequence according to an Ordering.

The sort is stable. That is, elements that are equal (as determined by lt ) appear in the same order in the sorted sequence as in the original.

  • ord
    • the ordering to be used to compare elements.
  • returns
    • a sequence consisting of the elements of this sequence sorted according to the ordering ord .
  • Definition Classes
    • SeqLike
  • See also
    • scala.math.Ordering

(defined at scala.collection.SeqLike)

def thisCollection: collection.Seq[A]

The underlying collection seen as an instance of Seq . By default this is implemented as the current collection object itself, but this can be overridden.

  • Attributes
    • protected[this]
  • Definition Classes
    • SeqLike → IterableLike → TraversableLike

(defined at scala.collection.SeqLike)

def toCollection(repr: ListBuffer[A]): collection.Seq[A]

A conversion from collections of type Repr to Seq objects. By default this is implemented as just a cast, but this can be overridden.

  • Attributes
    • protected[this]
  • Definition Classes
    • SeqLike → IterableLike → TraversableLike

(defined at scala.collection.SeqLike)

def union[B >: A, That](that: GenSeq[B])(implicit bf: CanBuildFrom[ListBuffer[A], B, That]): That

[use case]

Produces a new sequence which contains all elements of this list buffer and also all elements of a given sequence. xs union ys is equivalent to xs ++ ys .

Another way to express this is that xs union ys computes the order-preserving multi-set union of xs and ys . union is hence a counter-part of diff and intersect which also work on multi-sets.

  • that
    • the sequence to add.
  • returns
    • a new list buffer which contains all elements of this list buffer followed by all elements of that .
  • Definition Classes
    • SeqLike → GenSeqLike

(defined at scala.collection.SeqLike)

def updated[B >: A, That](index: Int, elem: B)(implicit bf: CanBuildFrom[ListBuffer[A], B, That]): That

[use case]

A copy of this list buffer with one single replaced element.

  • index
    • the position of the replacement
  • elem
    • the replacing element
  • returns
    • a copy of this list buffer with the element at position index replaced by elem .
  • Definition Classes
    • SeqLike → GenSeqLike

(defined at scala.collection.SeqLike)

def view(from: Int, until: Int): SeqView[A, ListBuffer[A]]

Creates a non-strict view of a slice of this sequence.

Note: the difference between view and slice is that view produces a view of the current sequence, whereas slice produces a new sequence.

Note: view(from, to) is equivalent to view.slice(from, to)

  • from
    • the index of the first element of the view
  • until
    • the index of the element following the view
  • returns
    • a non-strict view of a slice of this sequence, starting at index from and extending up to (but not including) index until .
  • Definition Classes
    • SeqLike → IterableLike → TraversableLike

(defined at scala.collection.SeqLike)

def view: SeqView[A, ListBuffer[A]]

Creates a non-strict view of this sequence.

  • returns
    • a non-strict view of this sequence.
  • Definition Classes
    • SeqLike → IterableLike → TraversableLike

(defined at scala.collection.SeqLike)

Value Members From scala.collection.TraversableLike

def ++:[B >: A, That](that: collection.Traversable[B])(implicit bf: CanBuildFrom[ListBuffer[A], B, That]): That

As with ++ , returns a new collection containing the elements from the left operand followed by the elements from the right operand.

It differs from ++ in that the right operand determines the type of the resulting collection rather than the left one. Mnemonic: the COLon is on the side of the new COLlection type.

Example:

scala> val x = List(1)
x: List[Int] = List(1)

scala> val y = LinkedList(2)
y: scala.collection.mutable.LinkedList[Int] = LinkedList(2)

scala> val z = x ++: y
z: scala.collection.mutable.LinkedList[Int] = LinkedList(1, 2)

This overload exists because: for the implementation of ++: we should reuse that of ++ because many collections override it with more efficient versions.

Since TraversableOnce has no ++ method, we have to implement that directly, but Traversable and down can use the overload.

  • B
    • the element type of the returned collection.
  • That
    • the class of the returned collection. Where possible, That is the same class as the current collection class Repr , but this depends on the element type B being admissible for that class, which means that an implicit instance of type CanBuildFrom[Repr, B, That] is found.
  • that
    • the traversable to append.
  • bf
    • an implicit value of class CanBuildFrom which determines the result class That from the current representation type Repr and and the new element type B .
  • returns
    • a new collection of type That which contains all elements of this traversable collection followed by all elements of that .
  • Definition Classes
    • TraversableLike

(defined at scala.collection.TraversableLike)

def ++:[B >: A, That](that: TraversableOnce[B])(implicit bf: CanBuildFrom[ListBuffer[A], B, That]): That

[use case]

As with ++ , returns a new collection containing the elements from the left operand followed by the elements from the right operand.

It differs from ++ in that the right operand determines the type of the resulting collection rather than the left one. Mnemonic: the COLon is on the side of the new COLlection type.

Example:

scala> val x = List(1)
x: List[Int] = List(1)

scala> val y = LinkedList(2)
y: scala.collection.mutable.LinkedList[Int] = LinkedList(2)

scala> val z = x ++: y
z: scala.collection.mutable.LinkedList[Int] = LinkedList(1, 2)
  • B
    • the element type of the returned collection.
  • that
    • the traversable to append.
  • returns
    • a new list buffer which contains all elements of this list buffer followed by all elements of that .
  • Definition Classes
    • TraversableLike

(defined at scala.collection.TraversableLike)

def ++[B >: A, That](that: GenTraversableOnce[B])(implicit bf: CanBuildFrom[ListBuffer[A], B, That]): That

[use case]

Returns a new list buffer containing the elements from the left hand operand followed by the elements from the right hand operand. The element type of the list buffer is the most specific superclass encompassing the element types of the two operands.

Example:

scala> val a = List(1)
a: List[Int] = List(1)

scala> val b = List(2)
b: List[Int] = List(2)

scala> val c = a ++ b
c: List[Int] = List(1, 2)

scala> val d = List('a')
d: List[Char] = List(a)

scala> val e = c ++ d
e: List[AnyVal] = List(1, 2, a)
  • B
    • the element type of the returned collection.
  • that
    • the traversable to append.
  • returns
    • a new list buffer which contains all elements of this list buffer followed by all elements of that .
  • Definition Classes
    • TraversableLike → GenTraversableLike

(defined at scala.collection.TraversableLike)

def collect[B, That](pf: PartialFunction[A, B])(implicit bf: CanBuildFrom[ListBuffer[A], B, That]): That

[use case]

Builds a new collection by applying a partial function to all elements of this list buffer on which the function is defined.

  • B
    • the element type of the returned collection.
  • pf
    • the partial function which filters and maps the list buffer.
  • returns
    • a new list buffer resulting from applying the given partial function pf to each element on which it is defined and collecting the results. The order of the elements is preserved.
  • Definition Classes
    • TraversableLike → GenTraversableLike

(defined at scala.collection.TraversableLike)

def dropWhile(p: (A) ⇒ Boolean): ListBuffer[A]

Drops longest prefix of elements that satisfy a predicate.

Note: might return different results for different runs, unless the underlying collection type is ordered.

  • returns
    • the longest suffix of this traversable collection whose first element does not satisfy the predicate p .
  • Definition Classes
    • TraversableLike → GenTraversableLike

(defined at scala.collection.TraversableLike)

def filter(p: (A) ⇒ Boolean): ListBuffer[A]

Selects all elements of this traversable collection which satisfy a predicate.

  • p
    • the predicate used to test elements.
  • returns
    • a new traversable collection consisting of all elements of this traversable collection that satisfy the given predicate p . The order of the elements is preserved.
  • Definition Classes
    • TraversableLike → GenTraversableLike

(defined at scala.collection.TraversableLike)

def filterNot(p: (A) ⇒ Boolean): ListBuffer[A]

Selects all elements of this traversable collection which do not satisfy a predicate.

  • p
    • the predicate used to test elements.
  • returns
    • a new traversable collection consisting of all elements of this traversable collection that do not satisfy the given predicate p . The order of the elements is preserved.
  • Definition Classes
    • TraversableLike → GenTraversableLike

(defined at scala.collection.TraversableLike)

def flatMap[B, That](f: (A) ⇒ GenTraversableOnce[B])(implicit bf: CanBuildFrom[ListBuffer[A], B, That]): That

[use case]

Builds a new collection by applying a function to all elements of this list buffer and using the elements of the resulting collections.

For example:

def getWords(lines: Seq[String]): Seq[String] = lines flatMap (line => line split "\\W+")

The type of the resulting collection is guided by the static type of list buffer. This might cause unexpected results sometimes. For example:

// lettersOf will return a Seq[Char] of likely repeated letters, instead of a Set
def lettersOf(words: Seq[String]) = words flatMap (word => word.toSet)

// lettersOf will return a Set[Char], not a Seq
def lettersOf(words: Seq[String]) = words.toSet flatMap (word => word.toSeq)

// xs will be an Iterable[Int]
val xs = Map("a" -> List(11,111), "b" -> List(22,222)).flatMap(_._2)

// ys will be a Map[Int, Int]
val ys = Map("a" -> List(1 -> 11,1 -> 111), "b" -> List(2 -> 22,2 -> 222)).flatMap(_._2)
  • B
    • the element type of the returned collection.
  • f
    • the function to apply to each element.
  • returns
    • a new list buffer resulting from applying the given collection-valued function f to each element of this list buffer and concatenating the results.
  • Definition Classes
    • TraversableLike → GenTraversableLike → FilterMonadic

(defined at scala.collection.TraversableLike)

def groupBy[K](f: (A) ⇒ K): immutable.Map[K, ListBuffer[A]]

Partitions this traversable collection into a map of traversable collections according to some discriminator function.

Note: this method is not re-implemented by views. This means when applied to a view it will always force the view and return a new traversable collection.

  • K
    • the type of keys returned by the discriminator function.
  • f
    • the discriminator function.
  • returns
    • A map from keys to traversable collections such that the following invariant holds:
    (xs groupBy f)(k) = xs filter (x => f(x) == k)
    
That is, every key `k` is bound to a traversable collection of those
elements `x` for which `f(x)` equals `k` .
  • Definition Classes
    • TraversableLike → GenTraversableLike

(defined at scala.collection.TraversableLike)

def init: ListBuffer[A]

Selects all elements except the last.

Note: might return different results for different runs, unless the underlying collection type is ordered.

  • returns
    • a traversable collection consisting of all elements of this traversable collection except the last one.
  • Definition Classes
    • TraversableLike → GenTraversableLike
  • Exceptions thrown
    • UnsupportedOperationException if the traversable collection is empty.

(defined at scala.collection.TraversableLike)

def inits: Iterator[ListBuffer[A]]

Iterates over the inits of this traversable collection. The first value will be this traversable collection and the final one will be an empty traversable collection, with the intervening values the results of successive applications of init .

  • returns
    • an iterator over all the inits of this traversable collection
  • Definition Classes
    • TraversableLike

Example:

List(1,2,3).inits = Iterator(List(1,2,3), List(1,2), List(1), Nil)

(defined at scala.collection.TraversableLike)

def map[B, That](f: (A) ⇒ B)(implicit bf: CanBuildFrom[ListBuffer[A], B, That]): That

[use case]

Builds a new collection by applying a function to all elements of this list buffer.

  • B
    • the element type of the returned collection.
  • f
    • the function to apply to each element.
  • returns
    • a new list buffer resulting from applying the given function f to each element of this list buffer and collecting the results.
  • Definition Classes
    • TraversableLike → GenTraversableLike → FilterMonadic

(defined at scala.collection.TraversableLike)

def partition(p: (A) ⇒ Boolean): (ListBuffer[A], ListBuffer[A])

Partitions this traversable collection in two traversable collections according to a predicate.

  • p
    • the predicate on which to partition.
  • returns
    • a pair of traversable collections: the first traversable collection consists of all elements that satisfy the predicate p and the second traversable collection consists of all elements that don’t. The relative order of the elements in the resulting traversable collections is the same as in the original traversable collection.
  • Definition Classes
    • TraversableLike → GenTraversableLike

(defined at scala.collection.TraversableLike)

def repr: ListBuffer[A]

The collection of type traversable collection underlying this TraversableLike object. By default this is implemented as the TraversableLike object itself, but this can be overridden.

  • Definition Classes
    • TraversableLike → GenTraversableLike

(defined at scala.collection.TraversableLike)

def scanLeft[B, That](z: B)(op: (B, A) ⇒ B)(implicit bf: CanBuildFrom[ListBuffer[A], B, That]): That

Produces a collection containing cumulative results of applying the operator going left to right.

Note: will not terminate for infinite-sized collections.

Note: might return different results for different runs, unless the underlying collection type is ordered.

  • B
    • the type of the elements in the resulting collection
  • That
    • the actual type of the resulting collection
  • z
    • the initial value
  • op
    • the binary operator applied to the intermediate result and the element
  • bf
    • an implicit value of class CanBuildFrom which determines the result class That from the current representation type Repr and and the new element type B .
  • returns
    • collection with intermediate results
  • Definition Classes
    • TraversableLike → GenTraversableLike

(defined at scala.collection.TraversableLike)

def scanRight[B, That](z: B)(op: (A, B) ⇒ B)(implicit bf: CanBuildFrom[ListBuffer[A], B, That]): That

Produces a collection containing cumulative results of applying the operator going right to left. The head of the collection is the last cumulative result.

Note: will not terminate for infinite-sized collections.

Note: might return different results for different runs, unless the underlying collection type is ordered.

Example:

List(1, 2, 3, 4).scanRight(0)(_ + _) == List(10, 9, 7, 4, 0)
  • B
    • the type of the elements in the resulting collection
  • That
    • the actual type of the resulting collection
  • z
    • the initial value
  • op
    • the binary operator applied to the intermediate result and the element
  • bf
    • an implicit value of class CanBuildFrom which determines the result class That from the current representation type Repr and and the new element type B .
  • returns
    • collection with intermediate results
  • Definition Classes
    • TraversableLike → GenTraversableLike
  • Annotations
    • @migration
  • Migration
    • (Changed in version 2.9.0) The behavior of scanRight has changed. The previous behavior can be reproduced with scanRight.reverse.

(defined at scala.collection.TraversableLike)

def scan[B >: A, That](z: B)(op: (B, B) ⇒ B)(implicit cbf: CanBuildFrom[ListBuffer[A], B, That]): That

Computes a prefix scan of the elements of the collection.

Note: The neutral element z may be applied more than once.

  • B
    • element type of the resulting collection
  • That
    • type of the resulting collection
  • z
    • neutral element for the operator op
  • op
    • the associative operator for the scan
  • cbf
    • combiner factory which provides a combiner
  • returns
    • a new traversable collection containing the prefix scan of the elements in this traversable collection
  • Definition Classes
    • TraversableLike → GenTraversableLike

(defined at scala.collection.TraversableLike)

def span(p: (A) ⇒ Boolean): (ListBuffer[A], ListBuffer[A])

Splits this traversable collection into a prefix/suffix pair according to a predicate.

Note: c span p is equivalent to (but possibly more efficient than) (c takeWhile p, c dropWhile p) , provided the evaluation of the predicate p does not cause any side-effects.

Note: might return different results for different runs, unless the underlying collection type is ordered.

  • returns
    • a pair consisting of the longest prefix of this traversable collection whose elements all satisfy p , and the rest of this traversable collection.
  • Definition Classes
    • TraversableLike → GenTraversableLike

(defined at scala.collection.TraversableLike)

def splitAt(n: Int): (ListBuffer[A], ListBuffer[A])

Splits this traversable collection into two at a given position. Note: c splitAt n is equivalent to (but possibly more efficient than) (c take n, c drop n) .

Note: might return different results for different runs, unless the underlying collection type is ordered.

  • n
    • the position at which to split.
  • returns
    • a pair of traversable collections consisting of the first n elements of this traversable collection, and the other elements.
  • Definition Classes
    • TraversableLike → GenTraversableLike

(defined at scala.collection.TraversableLike)

def tail: ListBuffer[A]

Selects all elements except the first.

Note: might return different results for different runs, unless the underlying collection type is ordered.

  • returns
    • a traversable collection consisting of all elements of this traversable collection except the first one.
  • Definition Classes
    • TraversableLike → GenTraversableLike
  • Exceptions thrown
    • UnsupportedOperationException if the traversable collection is empty.

(defined at scala.collection.TraversableLike)

def tails: Iterator[ListBuffer[A]]

Iterates over the tails of this traversable collection. The first value will be this traversable collection and the final one will be an empty traversable collection, with the intervening values the results of successive applications of tail .

  • returns
    • an iterator over all the tails of this traversable collection
  • Definition Classes
    • TraversableLike

Example:

List(1,2,3).tails = Iterator(List(1,2,3), List(2,3), List(3), Nil)

(defined at scala.collection.TraversableLike)

def toTraversable: collection.Traversable[A]

Converts this traversable collection to an unspecified Traversable. Will return the same collection if this instance is already Traversable.

Note: will not terminate for infinite-sized collections.

  • returns
    • a Traversable containing all elements of this traversable collection.
  • Definition Classes
    • TraversableLike → TraversableOnce → GenTraversableOnce
  • Annotations
    • @ deprecatedOverriding (message =…, since = “2.11.0”)

(defined at scala.collection.TraversableLike)

def withFilter(p: (A) ⇒ Boolean): FilterMonadic[A, ListBuffer[A]]

Creates a non-strict filter of this traversable collection.

Note: the difference between c filter p and c withFilter p is that the former creates a new collection, whereas the latter only restricts the domain of subsequent map , flatMap , foreach , and withFilter operations.

Note: might return different results for different runs, unless the underlying collection type is ordered.

  • p
    • the predicate used to test elements.
  • returns
    • an object of class WithFilter , which supports map , flatMap , foreach , and withFilter operations. All these operations apply to those elements of this traversable collection which satisfy the predicate p .
  • Definition Classes
    • TraversableLike → FilterMonadic

(defined at scala.collection.TraversableLike)

Value Members From scala.collection.TraversableOnce

def aggregate[B](z: ⇒ B)(seqop: (B, A) ⇒ B, combop: (B, B) ⇒ B): B

Aggregates the results of applying an operator to subsequent elements.

This is a more general form of fold and reduce . It is similar to foldLeft in that it doesn’t require the result to be a supertype of the element type. In addition, it allows parallel collections to be processed in chunks, and then combines the intermediate results.

aggregate splits the traversable or iterator into partitions and processes each partition by sequentially applying seqop , starting with z (like foldLeft ). Those intermediate results are then combined by using combop (like fold ). The implementation of this operation may operate on an arbitrary number of collection partitions (even 1), so combop may be invoked an arbitrary number of times (even 0).

As an example, consider summing up the integer values of a list of chars. The initial value for the sum is 0. First, seqop transforms each input character to an Int and adds it to the sum (of the partition). Then, combop just needs to sum up the intermediate results of the partitions:

List('a', 'b', 'c').aggregate(0)({ (sum, ch) => sum + ch.toInt }, { (p1, p2) => p1 + p2 })
  • B
    • the type of accumulated results
  • z
    • the initial value for the accumulated result of the partition - this will typically be the neutral element for the seqop operator (e.g. Nil for list concatenation or 0 for summation) and may be evaluated more than once
  • seqop
    • an operator used to accumulate results within a partition
  • combop
    • an associative operator used to combine results from different partitions
  • Definition Classes
    • TraversableOnce → GenTraversableOnce

(defined at scala.collection.TraversableOnce)

def collectFirst[B](pf: PartialFunction[A, B]): Option[B]

Finds the first element of the traversable or iterator for which the given partial function is defined, and applies the partial function to it.

Note: may not terminate for infinite-sized collections.

Note: might return different results for different runs, unless the underlying collection type is ordered.

  • pf
    • the partial function
  • returns
    • an option value containing pf applied to the first value for which it is defined, or None if none exists.
  • Definition Classes
    • TraversableOnce

Example:

Seq("a", 1, 5L).collectFirst({ case x: Int => x*10 }) = Some(10)

(defined at scala.collection.TraversableOnce)

def fold[A1 >: A](z: A1)(op: (A1, A1) ⇒ A1): A1

Folds the elements of this traversable or iterator using the specified associative binary operator.

The order in which operations are performed on elements is unspecified and may be nondeterministic.

Note: will not terminate for infinite-sized collections.

  • A1
    • a type parameter for the binary operator, a supertype of A .
  • z
    • a neutral element for the fold operation; may be added to the result an arbitrary number of times, and must not change the result (e.g., Nil for list concatenation, 0 for addition, or 1 for multiplication).
  • op
    • a binary operator that must be associative.
  • returns
    • the result of applying the fold operator op between all the elements and z , or z if this traversable or iterator is empty.
  • Definition Classes
    • TraversableOnce → GenTraversableOnce

(defined at scala.collection.TraversableOnce)

def maxBy[B](f: (A) ⇒ B)(implicit cmp: Ordering[B]): A

[use case]

Finds the first element which yields the largest value measured by function f.

  • B
    • The result type of the function f.
  • f
    • The measuring function.
  • returns
    • the first element of this list buffer with the largest value measured by function f.
  • Definition Classes
    • TraversableOnce → GenTraversableOnce

(defined at scala.collection.TraversableOnce)

def minBy[B](f: (A) ⇒ B)(implicit cmp: Ordering[B]): A

[use case]

Finds the first element which yields the smallest value measured by function f.

  • B
    • The result type of the function f.
  • f
    • The measuring function.
  • returns
    • the first element of this list buffer with the smallest value measured by function f.
  • Definition Classes
    • TraversableOnce → GenTraversableOnce

(defined at scala.collection.TraversableOnce)

def reduceOption[A1 >: A](op: (A1, A1) ⇒ A1): Option[A1]

Reduces the elements of this traversable or iterator, if any, using the specified associative binary operator.

The order in which operations are performed on elements is unspecified and may be nondeterministic.

  • A1
    • A type parameter for the binary operator, a supertype of A .
  • op
    • A binary operator that must be associative.
  • returns
    • An option value containing result of applying reduce operator op between all the elements if the collection is nonempty, and None otherwise.
  • Definition Classes
    • TraversableOnce → GenTraversableOnce

(defined at scala.collection.TraversableOnce)

def reduce[A1 >: A](op: (A1, A1) ⇒ A1): A1

Reduces the elements of this traversable or iterator using the specified associative binary operator.

The order in which operations are performed on elements is unspecified and may be nondeterministic.

  • A1
    • A type parameter for the binary operator, a supertype of A .
  • op
    • A binary operator that must be associative.
  • returns
    • The result of applying reduce operator op between all the elements if the traversable or iterator is nonempty.
  • Definition Classes
    • TraversableOnce → GenTraversableOnce
  • Exceptions thrown
    • UnsupportedOperationException if this traversable or iterator is empty.

(defined at scala.collection.TraversableOnce)

Value Members From scala.collection.generic.GenericTraversableTemplate

def flatten[B](implicit asTraversable: (A) ⇒ GenTraversableOnce[B]): ListBuffer[B]

[use case]

Converts this list buffer of traversable collections into a list buffer formed by the elements of these traversable collections.

The resulting collection’s type will be guided by the static type of list buffer. For example:

val xs = List(
           Set(1, 2, 3),
           Set(1, 2, 3)
         ).flatten
// xs == List(1, 2, 3, 1, 2, 3)

val ys = Set(
           List(1, 2, 3),
           List(3, 2, 1)
         ).flatten
// ys == Set(1, 2, 3)
  • B
    • the type of the elements of each traversable collection.
  • returns
    • a new list buffer resulting from concatenating all element list buffers.
  • Definition Classes
    • GenericTraversableTemplate

(defined at scala.collection.generic.GenericTraversableTemplate)

def genericBuilder[B]: Builder[B, ListBuffer[B]]

The generic builder that builds instances of Traversable at arbitrary element types.

  • Definition Classes
    • GenericTraversableTemplate

(defined at scala.collection.generic.GenericTraversableTemplate)

def newBuilder: Builder[A, ListBuffer[A]]

The builder that builds instances of type Traversable[A]

  • Attributes
    • protected[this]
  • Definition Classes
    • GenericTraversableTemplate → HasNewBuilder

(defined at scala.collection.generic.GenericTraversableTemplate)

def transpose[B](implicit asTraversable: (A) ⇒ GenTraversableOnce[B]): ListBuffer[ListBuffer[B]]

Transposes this collection of traversable collections into a collection of collections.

The resulting collection’s type will be guided by the static type of collection. For example:

val xs = List(
           Set(1, 2, 3),
           Set(4, 5, 6)).transpose
// xs == List(
//         List(1, 4),
//         List(2, 5),
//         List(3, 6))

val ys = Vector(
           List(1, 2, 3),
           List(4, 5, 6)).transpose
// ys == Vector(
//         Vector(1, 4),
//         Vector(2, 5),
//         Vector(3, 6))
  • B
    • the type of the elements of each traversable collection.
  • asTraversable
    • an implicit conversion which asserts that the element type of this collection is a Traversable .
  • returns
    • a two-dimensional collection of collections which has as n th row the n th column of this collection.
  • Definition Classes
    • GenericTraversableTemplate
  • Annotations
    • @migration
  • Migration
    • (Changed in version 2.9.0) transpose throws an IllegalArgumentException if collections are not uniformly sized.
  • Exceptions thrown
    • IllegalArgumentException if all collections in this collection are not of the same size.

(defined at scala.collection.generic.GenericTraversableTemplate)

def unzip3[A1, A2, A3](implicit asTriple: (A) ⇒ (A1, A2, A3)): (ListBuffer[A1], ListBuffer[A2], ListBuffer[A3])

Converts this collection of triples into three collections of the first, second, and third element of each triple.

val xs = Traversable(
           (1, "one", '1'),
           (2, "two", '2'),
           (3, "three", '3')).unzip3
// xs == (Traversable(1, 2, 3),
//        Traversable(one, two, three),
//        Traversable(1, 2, 3))
  • A1
    • the type of the first member of the element triples
  • A2
    • the type of the second member of the element triples
  • A3
    • the type of the third member of the element triples
  • asTriple
    • an implicit conversion which asserts that the element type of this collection is a triple.
  • returns
    • a triple of collections, containing the first, second, respectively third member of each element triple of this collection.
  • Definition Classes
    • GenericTraversableTemplate

(defined at scala.collection.generic.GenericTraversableTemplate)

def unzip[A1, A2](implicit asPair: (A) ⇒ (A1, A2)): (ListBuffer[A1], ListBuffer[A2])

Converts this collection of pairs into two collections of the first and second half of each pair.

val xs = Traversable(
           (1, "one"),
           (2, "two"),
           (3, "three")).unzip
// xs == (Traversable(1, 2, 3),
//        Traversable(one, two, three))
  • A1
    • the type of the first half of the element pairs
  • A2
    • the type of the second half of the element pairs
  • asPair
    • an implicit conversion which asserts that the element type of this collection is a pair.
  • returns
    • a pair of collections, containing the first, respectively second half of each element pair of this collection.
  • Definition Classes
    • GenericTraversableTemplate

(defined at scala.collection.generic.GenericTraversableTemplate)

Value Members From scala.collection.generic.Growable

def +=(elem1: A, elem2: A, elems: A*): ListBuffer.this.type

adds two or more elements to this growable collection.

  • elem1
    • the first element to add.
  • elem2
    • the second element to add.
  • elems
    • the remaining elements to add.
  • returns
    • the growable collection itself
  • Definition Classes
    • Growable

(defined at scala.collection.generic.Growable)

Value Members From scala.collection.generic.IterableForwarder

def sameElements[B >: A](that: GenIterable[B]): Boolean

[use case]

Checks if the other iterable collection contains the same elements in the same order as this list buffer.

  • that
    • the collection to compare with.
  • returns
    • true , if both collections contain the same elements in the same order, false otherwise.
  • Definition Classes
    • IterableForwarder → IterableLike → GenIterableLike

(defined at scala.collection.generic.IterableForwarder)

Value Members From scala.collection.generic.SeqForwarder

def containsSlice[B](that: GenSeq[B]): Boolean

Tests whether this sequence contains a given sequence as a slice.

Note: may not terminate for infinite-sized collections.

  • that
    • the sequence to test
  • returns
    • true if this sequence contains a slice with the same elements as that , otherwise false .
  • Definition Classes
    • SeqForwarder → SeqLike

(defined at scala.collection.generic.SeqForwarder)

def contains[A1 >: A](elem: A1): Boolean

Tests whether this sequence contains a given value as an element.

Note: may not terminate for infinite-sized collections.

  • elem
    • the element to test.
  • returns
    • true if this sequence has an element that is equal (as determined by == ) to elem , false otherwise.
  • Definition Classes
    • SeqForwarder → SeqLike

(defined at scala.collection.generic.SeqForwarder)

def corresponds[B](that: GenSeq[B])(p: (A, B) ⇒ Boolean): Boolean

Tests whether every element of this sequence relates to the corresponding element of another sequence by satisfying a test predicate.

  • B
    • the type of the elements of that
  • that
    • the other sequence
  • p
    • the test predicate, which relates elements from both sequences
  • returns
    • true if both sequences have the same length and p(x, y) is true for all corresponding elements x of this sequence and y of that , otherwise false .
  • Definition Classes
    • SeqForwarder → SeqLike → GenSeqLike

(defined at scala.collection.generic.SeqForwarder)

def endsWith[B](that: GenSeq[B]): Boolean

Tests whether this sequence ends with the given sequence.

Note: will not terminate for infinite-sized collections.

  • that
    • the sequence to test
  • returns
    • true if this sequence has that as a suffix, false otherwise.
  • Definition Classes
    • SeqForwarder → SeqLike → GenSeqLike

(defined at scala.collection.generic.SeqForwarder)

def indexOf[B >: A](elem: B): Int

[use case]

Finds index of first occurrence of some value in this list buffer.

  • elem
    • the element value to search for.
  • returns
    • the index of the first element of this list buffer that is equal (as determined by == ) to elem , or -1 , if none exists.
  • Definition Classes
    • SeqForwarder → GenSeqLike

(defined at scala.collection.generic.SeqForwarder)

def indexOf[B >: A](elem: B, from: Int): Int

[use case]

Finds index of first occurrence of some value in this list buffer after or at some start index.

  • elem
    • the element value to search for.
  • from
    • the start index
  • returns
    • the index >= from of the first element of this list buffer that is equal (as determined by == ) to elem , or -1 , if none exists.
  • Definition Classes
    • SeqForwarder → GenSeqLike

(defined at scala.collection.generic.SeqForwarder)

def indexOfSlice[B >: A](that: GenSeq[B]): Int

Finds first index where this sequence contains a given sequence as a slice.

Note: may not terminate for infinite-sized collections.

  • that
    • the sequence to test
  • returns
    • the first index such that the elements of this sequence starting at this index match the elements of sequence that , or -1 of no such subsequence exists.
  • Definition Classes
    • SeqForwarder → SeqLike

(defined at scala.collection.generic.SeqForwarder)

def indexOfSlice[B >: A](that: GenSeq[B], from: Int): Int

Finds first index after or at a start index where this sequence contains a given sequence as a slice.

Note: may not terminate for infinite-sized collections.

  • that
    • the sequence to test
  • from
    • the start index
  • returns
    • the first index >= from such that the elements of this sequence starting at this index match the elements of sequence that , or -1 of no such subsequence exists.
  • Definition Classes
    • SeqForwarder → SeqLike

(defined at scala.collection.generic.SeqForwarder)

def indexWhere(p: (A) ⇒ Boolean): Int

Finds index of first element satisfying some predicate.

Note: may not terminate for infinite-sized collections.

  • p
    • the predicate used to test elements.
  • returns
    • the index of the first element of this sequence that satisfies the predicate p , or -1 , if none exists.
  • Definition Classes
    • SeqForwarder → GenSeqLike

(defined at scala.collection.generic.SeqForwarder)

def indexWhere(p: (A) ⇒ Boolean, from: Int): Int

Finds index of the first element satisfying some predicate after or at some start index.

Note: may not terminate for infinite-sized collections.

  • p
    • the predicate used to test elements.
  • from
    • the start index
  • returns
    • the index >= from of the first element of this sequence that satisfies the predicate p , or -1 , if none exists.
  • Definition Classes
    • SeqForwarder → SeqLike → GenSeqLike

(defined at scala.collection.generic.SeqForwarder)

def indices: immutable.Range

Produces the range of all indices of this sequence.

  • returns
    • a Range value from 0 to one less than the length of this sequence.
  • Definition Classes
    • SeqForwarder → SeqLike

(defined at scala.collection.generic.SeqForwarder)

def isDefinedAt(x: Int): Boolean

Tests whether this sequence contains given index.

The implementations of methods apply and isDefinedAt turn a Seq[A] into a PartialFunction[Int, A] .

  • returns
    • true if this sequence contains an element at position idx , false otherwise.
  • Definition Classes
    • SeqForwarder → GenSeqLike → PartialFunction

(defined at scala.collection.generic.SeqForwarder)

def lastIndexOf[B >: A](elem: B): Int

[use case]

Finds index of last occurrence of some value in this list buffer.

  • elem
    • the element value to search for.
  • returns
    • the index of the last element of this list buffer that is equal (as determined by == ) to elem , or -1 , if none exists.
  • Definition Classes
    • SeqForwarder → GenSeqLike

(defined at scala.collection.generic.SeqForwarder)

def lastIndexOf[B >: A](elem: B, end: Int): Int

[use case]

Finds index of last occurrence of some value in this list buffer before or at a given end index.

  • elem
    • the element value to search for.
  • end
    • the end index.
  • returns
    • the index <= end of the last element of this list buffer that is equal (as determined by == ) to elem , or -1 , if none exists.
  • Definition Classes
    • SeqForwarder → GenSeqLike

(defined at scala.collection.generic.SeqForwarder)

def lastIndexOfSlice[B >: A](that: GenSeq[B]): Int

Finds last index where this sequence contains a given sequence as a slice.

Note: will not terminate for infinite-sized collections.

  • that
    • the sequence to test
  • returns
    • the last index such that the elements of this sequence starting a this index match the elements of sequence that , or -1 of no such subsequence exists.
  • Definition Classes
    • SeqForwarder → SeqLike

(defined at scala.collection.generic.SeqForwarder)

def lastIndexOfSlice[B >: A](that: GenSeq[B], end: Int): Int

Finds last index before or at a given end index where this sequence contains a given sequence as a slice.

  • that
    • the sequence to test
  • end
    • the end index
  • returns
    • the last index <= end such that the elements of this sequence starting at this index match the elements of sequence that , or -1 of no such subsequence exists.
  • Definition Classes
    • SeqForwarder → SeqLike

(defined at scala.collection.generic.SeqForwarder)

def lastIndexWhere(p: (A) ⇒ Boolean): Int

Finds index of last element satisfying some predicate.

Note: will not terminate for infinite-sized collections.

  • p
    • the predicate used to test elements.
  • returns
    • the index of the last element of this sequence that satisfies the predicate p , or -1 , if none exists.
  • Definition Classes
    • SeqForwarder → GenSeqLike

(defined at scala.collection.generic.SeqForwarder)

def lastIndexWhere(p: (A) ⇒ Boolean, end: Int): Int

Finds index of last element satisfying some predicate before or at given end index.

  • p
    • the predicate used to test elements.
  • returns
    • the index <= end of the last element of this sequence that satisfies the predicate p , or -1 , if none exists.
  • Definition Classes
    • SeqForwarder → SeqLike → GenSeqLike

(defined at scala.collection.generic.SeqForwarder)

def lengthCompare(len: Int): Int

Compares the length of this sequence to a test value.

  • len
    • the test value that gets compared with the length.
  • returns
    • A value x where
    x <  0       if this.length <  len
    x == 0       if this.length == len
    x >  0       if this.length >  len
    
The method as implemented here does not call `length` directly; its running
time is `O(length min len)` instead of `O(length)` . The method should be
overwritten if computing `length` is cheap.
  • Definition Classes
    • SeqForwarder → SeqLike

(defined at scala.collection.generic.SeqForwarder)

def prefixLength(p: (A) ⇒ Boolean): Int

Returns the length of the longest prefix whose elements all satisfy some predicate.

Note: may not terminate for infinite-sized collections.

  • p
    • the predicate used to test elements.
  • returns
    • the length of the longest prefix of this sequence such that every element of the segment satisfies the predicate p .
  • Definition Classes
    • SeqForwarder → GenSeqLike

(defined at scala.collection.generic.SeqForwarder)

def segmentLength(p: (A) ⇒ Boolean, from: Int): Int

Computes length of longest segment whose elements all satisfy some predicate.

Note: may not terminate for infinite-sized collections.

  • p
    • the predicate used to test elements.
  • from
    • the index where the search starts.
  • returns
    • the length of the longest segment of this sequence starting from index from such that every element of the segment satisfies the predicate p .
  • Definition Classes
    • SeqForwarder → SeqLike → GenSeqLike

(defined at scala.collection.generic.SeqForwarder)

def startsWith[B](that: GenSeq[B]): Boolean

Tests whether this sequence starts with the given sequence.

  • that
    • the sequence to test
  • returns
    • true if this collection has that as a prefix, false otherwise.
  • Definition Classes
    • SeqForwarder → GenSeqLike

(defined at scala.collection.generic.SeqForwarder)

def startsWith[B](that: GenSeq[B], offset: Int): Boolean

Tests whether this sequence contains the given sequence at a given index.

Note : If the both the receiver object this and the argument that are infinite sequences this method may not terminate.

  • that
    • the sequence to test
  • offset
    • the index where the sequence is searched.
  • returns
    • true if the sequence that is contained in this sequence at index offset , otherwise false .
  • Definition Classes
    • SeqForwarder → SeqLike → GenSeqLike

(defined at scala.collection.generic.SeqForwarder)

Value Members From scala.collection.generic.Shrinkable

def --=(xs: TraversableOnce[A]): ListBuffer.this.type

Removes all elements produced by an iterator from this shrinkable collection.

  • xs
    • the iterator producing the elements to remove.
  • returns
    • the shrinkable collection itself
  • Definition Classes
    • Shrinkable

(defined at scala.collection.generic.Shrinkable)

def -=(elem1: A, elem2: A, elems: A*): ListBuffer.this.type

Removes two or more elements from this shrinkable collection.

  • elem1
    • the first element to remove.
  • elem2
    • the second element to remove.
  • elems
    • the remaining elements to remove.
  • returns
    • the shrinkable collection itself
  • Definition Classes
    • Shrinkable

(defined at scala.collection.generic.Shrinkable)

Value Members From scala.collection.generic.TraversableForwarder

def /:[B](z: B)(op: (B, A) ⇒ B): B

Applies a binary operator to a start value and all elements of this collection, going left to right.

Note: /: is alternate syntax for foldLeft ; z /: xs is the same as xs foldLeft z .

Examples:

Note that the folding function used to compute b is equivalent to that used to compute c.

scala> val a = List(1,2,3,4)
a: List[Int] = List(1, 2, 3, 4)

scala> val b = (5 /: a)(_+_)
b: Int = 15

scala> val c = (5 /: a)((x,y) => x + y)
c: Int = 15

Note: will not terminate for infinite-sized collections.

Note: might return different results for different runs, unless the underlying collection type is ordered. or the operator is associative and commutative.

  • B
    • the result type of the binary operator.
  • z
    • the start value.
  • op
    • the binary operator.
  • returns
    • the result of inserting op between consecutive elements of this collection, going left to right with the start value z on the left:
    op(...op(op(z, x_1), x_2), ..., x_n)
    
where `x1, ..., xn` are the elements of this collection.
  • Definition Classes
    • TraversableForwarder → TraversableOnce → GenTraversableOnce

(defined at scala.collection.generic.TraversableForwarder)

def :\[B](z: B)(op: (A, B) ⇒ B): B

Applies a binary operator to all elements of this collection and a start value, going right to left.

Note: :\ is alternate syntax for foldRight ; xs :\ z is the same as xs foldRight z .

Note: will not terminate for infinite-sized collections.

Note: might return different results for different runs, unless the underlying collection type is ordered. or the operator is associative and commutative.

Examples:

Note that the folding function used to compute b is equivalent to that used to compute c.

scala> val a = List(1,2,3,4)
a: List[Int] = List(1, 2, 3, 4)

scala> val b = (a :\ 5)(_+_)
b: Int = 15

scala> val c = (a :\ 5)((x,y) => x + y)
c: Int = 15
  • B
    • the result type of the binary operator.
  • z
    • the start value
  • op
    • the binary operator
  • returns
    • the result of inserting op between consecutive elements of this collection, going right to left with the start value z on the right:
    op(x_1, op(x_2, ... op(x_n, z)...))
    
where `x1, ..., xn` are the elements of this collection.
  • Definition Classes
    • TraversableForwarder → TraversableOnce → GenTraversableOnce

(defined at scala.collection.generic.TraversableForwarder)

def addString(b: StringBuilder): StringBuilder

Appends all elements of this collection to a string builder. The written text consists of the string representations (w.r.t. the method toString ) of all elements of this collection without any separator string.

Example:

scala> val a = List(1,2,3,4)
a: List[Int] = List(1, 2, 3, 4)

scala> val b = new StringBuilder()
b: StringBuilder =

scala> val h = a.addString(b)
h: StringBuilder = 1234
  • b
    • the string builder to which elements are appended.
  • returns
    • the string builder b to which elements were appended.
  • Definition Classes
    • TraversableForwarder → TraversableOnce

(defined at scala.collection.generic.TraversableForwarder)

def addString(b: StringBuilder, sep: String): StringBuilder

Appends all elements of this collection to a string builder using a separator string. The written text consists of the string representations (w.r.t. the method toString ) of all elements of this collection, separated by the string sep .

Example:

scala> val a = List(1,2,3,4)
a: List[Int] = List(1, 2, 3, 4)

scala> val b = new StringBuilder()
b: StringBuilder =

scala> a.addString(b, ", ")
res0: StringBuilder = 1, 2, 3, 4
  • b
    • the string builder to which elements are appended.
  • sep
    • the separator string.
  • returns
    • the string builder b to which elements were appended.
  • Definition Classes
    • TraversableForwarder → TraversableOnce

(defined at scala.collection.generic.TraversableForwarder)

def addString(b: StringBuilder, start: String, sep: String, end: String): StringBuilder

Appends all elements of this collection to a string builder using start, end, and separator strings. The written text begins with the string start and ends with the string end . Inside, the string representations (w.r.t. the method toString ) of all elements of this collection are separated by the string sep .

Example:

scala> val a = List(1,2,3,4)
a: List[Int] = List(1, 2, 3, 4)

scala> val b = new StringBuilder()
b: StringBuilder =

scala> a.addString(b , "List(" , ", " , ")")
res5: StringBuilder = List(1, 2, 3, 4)
  • b
    • the string builder to which elements are appended.
  • start
    • the starting string.
  • sep
    • the separator string.
  • end
    • the ending string.
  • returns
    • the string builder b to which elements were appended.
  • Definition Classes
    • TraversableForwarder → TraversableOnce

(defined at scala.collection.generic.TraversableForwarder)

def copyToArray[B >: A](xs: Array[B]): Unit

[use case]

Copies the elements of this list buffer to an array. Fills the given array xs with values of this list buffer. Copying will stop once either the end of the current list buffer is reached, or the end of the target array is reached.

  • xs
    • the array to fill.
  • Definition Classes
    • TraversableForwarder → TraversableOnce → GenTraversableOnce

(defined at scala.collection.generic.TraversableForwarder)

def copyToArray[B >: A](xs: Array[B], start: Int): Unit

[use case]

Copies the elements of this list buffer to an array. Fills the given array xs with values of this list buffer, beginning at index start . Copying will stop once either the end of the current list buffer is reached, or the end of the target array is reached.

  • xs
    • the array to fill.
  • start
    • the starting index.
  • Definition Classes
    • TraversableForwarder → TraversableOnce → GenTraversableOnce

(defined at scala.collection.generic.TraversableForwarder)

def copyToArray[B >: A](xs: Array[B], start: Int, len: Int): Unit

[use case]

Copies the elements of this list buffer to an array. Fills the given array xs with at most len elements of this list buffer, starting at position start . Copying will stop once either the end of the current list buffer is reached, or the end of the target array is reached, or len elements have been copied.

  • xs
    • the array to fill.
  • start
    • the starting index.
  • len
    • the maximal number of elements to copy.
  • Definition Classes
    • TraversableForwarder → TraversableLike → TraversableOnce → GenTraversableOnce

(defined at scala.collection.generic.TraversableForwarder)

def copyToBuffer[B >: A](dest: Buffer[B]): Unit

Copies all elements of this collection to a buffer.

Note: will not terminate for infinite-sized collections.

  • dest
    • The buffer to which elements are copied.
  • Definition Classes
    • TraversableForwarder → TraversableOnce

(defined at scala.collection.generic.TraversableForwarder)

def count(p: (A) ⇒ Boolean): Int

Counts the number of elements in the collection which satisfy a predicate.

  • p
    • the predicate used to test elements.
  • returns
    • the number of elements satisfying the predicate p .
  • Definition Classes
    • TraversableForwarder → TraversableOnce → GenTraversableOnce

(defined at scala.collection.generic.TraversableForwarder)

def exists(p: (A) ⇒ Boolean): Boolean

Tests whether a predicate holds for at least one element of this collection.

Note: may not terminate for infinite-sized collections.

  • p
    • the predicate used to test elements.
  • returns
    • false if this collection is empty, otherwise true if the given predicate p holds for some of the elements of this collection, otherwise false
  • Definition Classes
    • TraversableForwarder → TraversableLike → TraversableOnce → GenTraversableOnce

(defined at scala.collection.generic.TraversableForwarder)

def find(p: (A) ⇒ Boolean): Option[A]

Finds the first element of the collection satisfying a predicate, if any.

Note: may not terminate for infinite-sized collections.

Note: might return different results for different runs, unless the underlying collection type is ordered.

  • p
    • the predicate used to test elements.
  • returns
    • an option value containing the first element in the collection that satisfies p , or None if none exists.
  • Definition Classes
    • TraversableForwarder → TraversableLike → TraversableOnce → GenTraversableOnce

(defined at scala.collection.generic.TraversableForwarder)

def foldLeft[B](z: B)(op: (B, A) ⇒ B): B

Applies a binary operator to a start value and all elements of this collection, going left to right.

Note: will not terminate for infinite-sized collections.

Note: might return different results for different runs, unless the underlying collection type is ordered. or the operator is associative and commutative.

  • B
    • the result type of the binary operator.
  • z
    • the start value.
  • op
    • the binary operator.
  • returns
    • the result of inserting op between consecutive elements of this collection, going left to right with the start value z on the left:
    op(...op(z, x_1), x_2, ..., x_n)
    
where `x1, ..., xn` are the elements of this collection. Returns `z` if this
collection is empty.
  • Definition Classes
    • TraversableForwarder → TraversableOnce → GenTraversableOnce

(defined at scala.collection.generic.TraversableForwarder)

def foldRight[B](z: B)(op: (A, B) ⇒ B): B

Applies a binary operator to all elements of this collection and a start value, going right to left.

Note: will not terminate for infinite-sized collections.

Note: might return different results for different runs, unless the underlying collection type is ordered. or the operator is associative and commutative.

  • B
    • the result type of the binary operator.
  • z
    • the start value.
  • op
    • the binary operator.
  • returns
    • the result of inserting op between consecutive elements of this collection, going right to left with the start value z on the right:
    op(x_1, op(x_2, ... op(x_n, z)...))
    
where `x1, ..., xn` are the elements of this collection. Returns `z` if this
collection is empty.
  • Definition Classes
    • TraversableForwarder → TraversableOnce → GenTraversableOnce

(defined at scala.collection.generic.TraversableForwarder)

def forall(p: (A) ⇒ Boolean): Boolean

Tests whether a predicate holds for all elements of this collection.

Note: may not terminate for infinite-sized collections.

  • p
    • the predicate used to test elements.
  • returns
    • true if this collection is empty or the given predicate p holds for all elements of this collection, otherwise false .
  • Definition Classes
    • TraversableForwarder → TraversableLike → TraversableOnce → GenTraversableOnce

(defined at scala.collection.generic.TraversableForwarder)

def foreach[U](f: (A) ⇒ U): Unit

[use case]

  • f
    • the function that is applied for its side-effect to every element. The result of function f is discarded.
  • Definition Classes
    • TraversableForwarder → GenericTraversableTemplate → TraversableLike → GenTraversableLike → TraversableOnce → GenTraversableOnce → FilterMonadic

(defined at scala.collection.generic.TraversableForwarder)

def mkString(sep: String): String

Displays all elements of this collection in a string using a separator string.

  • sep
    • the separator string.
  • returns
    • a string representation of this collection. In the resulting string the string representations (w.r.t. the method toString ) of all elements of this collection are separated by the string sep .
  • Definition Classes
    • TraversableForwarder → TraversableOnce → GenTraversableOnce

Example:

List(1, 2, 3).mkString("|") = "1|2|3"

(defined at scala.collection.generic.TraversableForwarder)

def mkString(start: String, sep: String, end: String): String

Displays all elements of this collection in a string using start, end, and separator strings.

  • start
    • the starting string.
  • sep
    • the separator string.
  • end
    • the ending string.
  • returns
    • a string representation of this collection. The resulting string begins with the string start and ends with the string end . Inside, the string representations (w.r.t. the method toString ) of all elements of this collection are separated by the string sep .
  • Definition Classes
    • TraversableForwarder → TraversableOnce → GenTraversableOnce

Example:

List(1, 2, 3).mkString("(", "; ", ")") = "(1; 2; 3)"

(defined at scala.collection.generic.TraversableForwarder)

def reduceLeftOption[B >: A](op: (B, A) ⇒ B): Option[B]

Optionally applies a binary operator to all elements of this collection, going left to right.

Note: will not terminate for infinite-sized collections.

Note: might return different results for different runs, unless the underlying collection type is ordered. or the operator is associative and commutative.

  • B
    • the result type of the binary operator.
  • op
    • the binary operator.
  • returns
    • an option value containing the result of reduceLeft(op) if this collection is nonempty, None otherwise.
  • Definition Classes
    • TraversableForwarder → TraversableOnce → GenTraversableOnce

(defined at scala.collection.generic.TraversableForwarder)

def reduceLeft[B >: A](op: (B, A) ⇒ B): B

Applies a binary operator to all elements of this collection, going left to right.

Note: will not terminate for infinite-sized collections.

Note: might return different results for different runs, unless the underlying collection type is ordered. or the operator is associative and commutative.

  • B
    • the result type of the binary operator.
  • op
    • the binary operator.
  • returns
    • the result of inserting op between consecutive elements of this collection, going left to right:
    op( op( ... op(x_1, x_2) ..., x_{n-1}), x_n)
    
where `x1, ..., xn` are the elements of this collection.
  • Definition Classes
    • TraversableForwarder → TraversableOnce
  • Exceptions thrown
    • UnsupportedOperationException if this collection is empty.

(defined at scala.collection.generic.TraversableForwarder)

def reduceRightOption[B >: A](op: (A, B) ⇒ B): Option[B]

Optionally applies a binary operator to all elements of this collection, going right to left.

Note: will not terminate for infinite-sized collections.

Note: might return different results for different runs, unless the underlying collection type is ordered. or the operator is associative and commutative.

  • B
    • the result type of the binary operator.
  • op
    • the binary operator.
  • returns
    • an option value containing the result of reduceRight(op) if this collection is nonempty, None otherwise.
  • Definition Classes
    • TraversableForwarder → TraversableOnce → GenTraversableOnce

(defined at scala.collection.generic.TraversableForwarder)

def reduceRight[B >: A](op: (A, B) ⇒ B): B

Applies a binary operator to all elements of this collection, going right to left.

Note: will not terminate for infinite-sized collections.

Note: might return different results for different runs, unless the underlying collection type is ordered. or the operator is associative and commutative.

  • B
    • the result type of the binary operator.
  • op
    • the binary operator.
  • returns
    • the result of inserting op between consecutive elements of this collection, going right to left:
    op(x_1, op(x_2, ..., op(x_{n-1}, x_n)...))
    
where `x1, ..., xn` are the elements of this collection.
  • Definition Classes
    • TraversableForwarder → TraversableOnce → GenTraversableOnce
  • Exceptions thrown
    • UnsupportedOperationException if this collection is empty.

(defined at scala.collection.generic.TraversableForwarder)

def toBuffer[B >: A]: Buffer[B]

Uses the contents of this collection to create a new mutable buffer.

Note: will not terminate for infinite-sized collections.

  • returns
    • a buffer containing all elements of this collection.
  • Definition Classes
    • TraversableForwarder → TraversableOnce → GenTraversableOnce

(defined at scala.collection.generic.TraversableForwarder)

def toIndexedSeq: immutable.IndexedSeq[A]

Converts this collection to an indexed sequence.

Note: will not terminate for infinite-sized collections.

  • returns
    • an indexed sequence containing all elements of this collection.
  • Definition Classes
    • TraversableForwarder → TraversableOnce → GenTraversableOnce

(defined at scala.collection.generic.TraversableForwarder)

def toIterable: collection.Iterable[A]

Converts this collection to an iterable collection. Note that the choice of target Iterable is lazy in this default implementation as this TraversableOnce may be lazy and unevaluated (i.e. it may be an iterator which is only traversable once).

Note: will not terminate for infinite-sized collections.

  • returns
    • an Iterable containing all elements of this collection.
  • Definition Classes
    • TraversableForwarder → TraversableOnce → GenTraversableOnce

(defined at scala.collection.generic.TraversableForwarder)

def toMap[T, U](implicit ev: <:<[A, (T, U)]): immutable.Map[T, U]

[use case]

Converts this list buffer to a map. This method is unavailable unless the elements are members of Tuple2, each ((T, U)) becoming a key-value pair in the map. Duplicate keys will be overwritten by later keys: if this is an unordered collection, which key is in the resulting map is undefined.

  • returns
    • a map of type immutable.Map[T, U] containing all key/value pairs of type (T, U) of this list buffer.
  • Definition Classes
    • TraversableForwarder → TraversableOnce → GenTraversableOnce

(defined at scala.collection.generic.TraversableForwarder)

def toSeq: collection.Seq[A]

Converts this collection to a sequence. As with toIterable , it’s lazy in this default implementation, as this TraversableOnce may be lazy and unevaluated.

Note: will not terminate for infinite-sized collections.

  • returns
    • a sequence containing all elements of this collection.
  • Definition Classes
    • TraversableForwarder → TraversableOnce → GenTraversableOnce

(defined at scala.collection.generic.TraversableForwarder)

def toSet[B >: A]: immutable.Set[B]

Converts this collection to a set.

Note: will not terminate for infinite-sized collections.

  • returns
    • a set containing all elements of this collection.
  • Definition Classes
    • TraversableForwarder → TraversableOnce → GenTraversableOnce

(defined at scala.collection.generic.TraversableForwarder)

def toStream: immutable.Stream[A]

Converts this collection to a stream.

  • returns
    • a stream containing all elements of this collection.
  • Definition Classes
    • TraversableForwarder → TraversableLike → GenTraversableOnce

(defined at scala.collection.generic.TraversableForwarder)

Deprecated Value Members From scala.collection.mutable.BufferLike

def <<(cmd: Message[A]): Unit

Send a message to this scriptable object.

  • cmd
    • the message to send.
  • Definition Classes
    • BufferLike → Scriptable
  • Annotations
    • @ deprecated
  • Deprecated
    • (Since version 2.11.0) Scripting is deprecated.

(defined at scala.collection.mutable.BufferLike)

Value Members From scala.collection.mutable.BufferLike

def ++(xs: GenTraversableOnce[A]): ListBuffer[A]

Creates a new collection containing both the elements of this collection and the provided traversable object.

  • xs
    • the traversable object.
  • returns
    • a new collection consisting of all the elements of this collection and xs .
  • Definition Classes
    • BufferLike
  • Annotations
    • @migration
  • Migration
    • (Changed in version 2.8.0) ++ creates a new buffer. Use ++= to add an element from this buffer and return that buffer itself.

(defined at scala.collection.mutable.BufferLike)

def -(elem: A): ListBuffer[A]

Creates a new collection with all the elements of this collection except elem .

  • elem
    • the element to remove.
  • returns
    • a new collection consisting of all the elements of this collection except elem .
  • Definition Classes
    • BufferLike → Subtractable
  • Annotations
    • @migration
  • Migration
    • (Changed in version 2.8.0) - creates a new buffer. Use -= to remove an element from this buffer and return that buffer itself.

(defined at scala.collection.mutable.BufferLike)

def -(elem1: A, elem2: A, elems: A*): ListBuffer[A]

Creates a new collection with all the elements of this collection except the two or more specified elements.

  • elem1
    • the first element to remove.
  • elem2
    • the second element to remove.
  • elems
    • the remaining elements to remove.
  • returns
    • a new collection consisting of all the elements of this collection except elem1 , elem2 and those in elems .
  • Definition Classes
    • BufferLike → Subtractable
  • Annotations
    • @migration
  • Migration
    • (Changed in version 2.8.0) - creates a new buffer. Use -= to remove an element from this buffer and return that buffer itself.

(defined at scala.collection.mutable.BufferLike)

def --(xs: GenTraversableOnce[A]): ListBuffer[A]

Creates a new collection with all the elements of this collection except those provided by the specified traversable object.

  • xs
    • the traversable object.
  • returns
    • a new collection with all the elements of this collection except those in xs
  • Definition Classes
    • BufferLike → Subtractable
  • Annotations
    • @migration
  • Migration
    • (Changed in version 2.8.0) -- creates a new buffer. Use --= to remove an element from this buffer and return that buffer itself.

(defined at scala.collection.mutable.BufferLike)

def append(elems: A*): Unit

Appends the given elements to this buffer.

  • elems
    • the elements to append.
  • Definition Classes
    • BufferLike

(defined at scala.collection.mutable.BufferLike)

def appendAll(xs: TraversableOnce[A]): Unit

Appends the elements contained in a traversable object to this buffer.

  • xs
    • the traversable object containing the elements to append.
  • Definition Classes
    • BufferLike

(defined at scala.collection.mutable.BufferLike)

def insert(n: Int, elems: A*): Unit

Inserts new elements at a given index into this buffer.

  • n
    • the index where new elements are inserted.
  • elems
    • the traversable collection containing the elements to insert.
  • Definition Classes
    • BufferLike
  • Exceptions thrown
    • IndexOutOfBoundsException if the index n is not in the valid range 0 <= n <= length .

(defined at scala.collection.mutable.BufferLike)

def prepend(elems: A*): Unit

Prepends given elements to this buffer.

  • elems
    • the elements to prepend.
  • Definition Classes
    • BufferLike

(defined at scala.collection.mutable.BufferLike)

def prependAll(xs: TraversableOnce[A]): Unit

Prepends the elements contained in a traversable object to this buffer.

  • xs
    • the collection containing the elements to prepend.
  • Definition Classes
    • BufferLike

(defined at scala.collection.mutable.BufferLike)

def trimEnd(n: Int): Unit

Removes the last n elements of this buffer.

  • n
    • the number of elements to remove from the end of this buffer.
  • Definition Classes
    • BufferLike

(defined at scala.collection.mutable.BufferLike)

def trimStart(n: Int): Unit

Removes the first n elements of this buffer.

  • n
    • the number of elements to remove from the beginning of this buffer.
  • Definition Classes
    • BufferLike

(defined at scala.collection.mutable.BufferLike)

Value Members From scala.collection.mutable.Builder

def mapResult[NewTo](f: (immutable.List[A]) ⇒ NewTo): Builder[A, NewTo]

Creates a new builder by applying a transformation function to the results of this builder.

  • NewTo
    • the type of collection returned by f .
  • f
    • the transformation function.
  • returns
    • a new builder which is the same as the current builder except that a transformation function is applied to this builder’s result.
  • Definition Classes
    • Builder
  • Note
    • The original builder should no longer be used after mapResult is called.

(defined at scala.collection.mutable.Builder)

def sizeHint(size: Int): Unit

Gives a hint how many elements are expected to be added when the next result is called. Some builder classes will optimize their representation based on the hint. However, builder implementations are still required to work correctly even if the hint is wrong, i.e. a different number of elements is added.

  • size
    • the hint how many elements will be added.
  • Definition Classes
    • Builder

(defined at scala.collection.mutable.Builder)

def sizeHint(coll: TraversableLike[_, _]): Unit

Gives a hint that one expects the result of this builder to have the same size as the given collection, plus some delta. This will provide a hint only if the collection is known to have a cheap size method. Currently this is assumed to be the case if and only if the collection is of type IndexedSeqLike . Some builder classes will optimize their representation based on the hint. However, builder implementations are still required to work correctly even if the hint is wrong, i.e. a different number of elements is added.

  • coll
    • the collection which serves as a hint for the result’s size.
  • Definition Classes
    • Builder

(defined at scala.collection.mutable.Builder)

def sizeHint(coll: TraversableLike[_, _], delta: Int): Unit

Gives a hint that one expects the result of this builder to have the same size as the given collection, plus some delta. This will provide a hint only if the collection is known to have a cheap size method. Currently this is assumed to be the case if and only if the collection is of type IndexedSeqLike . Some builder classes will optimize their representation based on the hint. However, builder implementations are still required to work correctly even if the hint is wrong, i.e. a different number of elements is added.

  • coll
    • the collection which serves as a hint for the result’s size.
  • delta
    • a correction to add to the coll.size to produce the size hint.
  • Definition Classes
    • Builder

(defined at scala.collection.mutable.Builder)

def sizeHintBounded(size: Int, boundingColl: TraversableLike[_, _]): Unit

Gives a hint how many elements are expected to be added when the next result is called, together with an upper bound given by the size of some other collection. Some builder classes will optimize their representation based on the hint. However, builder implementations are still required to work correctly even if the hint is wrong, i.e. a different number of elements is added.

  • size
    • the hint how many elements will be added.
  • boundingColl
    • the bounding collection. If it is an IndexedSeqLike, then sizes larger than collection’s size are reduced.
  • Definition Classes
    • Builder

(defined at scala.collection.mutable.Builder)

Instance Constructors From scala.collection.mutable.ListBuffer

new ListBuffer()

(defined at scala.collection.mutable.ListBuffer)

Value Members From scala.collection.mutable.ListBuffer

def ++=(xs: TraversableOnce[A]): ListBuffer.this.type

Appends all elements produced by a TraversableOnce to this list buffer.

  • xs
    • the TraversableOnce producing the elements to append.
  • returns
    • the list buffer itself.
  • Definition Classes
    • ListBuffer → Growable

(defined at scala.collection.mutable.ListBuffer)

def ++=:(xs: TraversableOnce[A]): ListBuffer.this.type

Prepends elements to this buffer.

  • xs
    • the TraversableOnce containing the elements to prepend.
  • returns
    • the buffer itself.
  • Definition Classes
    • ListBuffer → BufferLike

(defined at scala.collection.mutable.ListBuffer)

def +=(x: A): ListBuffer.this.type

Appends a single element to this buffer. This operation takes constant time.

  • x
    • the element to append.
  • returns
    • this list buffer.
  • Definition Classes
    • ListBuffer → Builder → BufferLike → Growable

(defined at scala.collection.mutable.ListBuffer)

def +=:(x: A): ListBuffer.this.type

Prepends a single element to this buffer. This operation takes constant time.

  • x
    • the element to prepend.
  • returns
    • this list buffer.
  • Definition Classes
    • ListBuffer → BufferLike

(defined at scala.collection.mutable.ListBuffer)

def -=(elem: A): ListBuffer.this.type

Remove a single element from this buffer. May take time linear in the buffer size.

  • elem
    • the element to remove.
  • returns
    • this list buffer.
  • Definition Classes
    • ListBuffer → BufferLike → Shrinkable

(defined at scala.collection.mutable.ListBuffer)

def apply(n: Int): A

Selects an element by its index in the list buffer.

Example:

scala> val x = List(1, 2, 3, 4, 5)
x: List[Int] = List(1, 2, 3, 4, 5)

scala> x(3)
res1: Int = 4
  • returns
    • the element of this list buffer at index idx , where 0 indicates the first element.
  • Definition Classes
    • ListBuffer → SeqForwarder → BufferLike → SeqLike → GenSeqLike → Function1
  • Exceptions thrown
    • IndexOutOfBoundsException if idx does not satisfy 0 <= idx < length .

(defined at scala.collection.mutable.ListBuffer)

def clone(): ListBuffer[A]

Returns a clone of this buffer.

  • returns
    • a ListBuffer with the same elements.
  • Definition Classes
    • ListBuffer → BufferLike → Cloneable → AnyRef

(defined at scala.collection.mutable.ListBuffer)

def companion: GenericCompanion[ListBuffer]

The factory companion object that builds instances of class ListBuffer . (or its Iterable superclass where class ListBuffer is not a Seq .)

  • Definition Classes
    • ListBuffer → Buffer → Seq → Iterable → Traversable → Seq → GenSeq → Iterable → GenIterable → Traversable → GenTraversable → GenericTraversableTemplate

(defined at scala.collection.mutable.ListBuffer)

def equals(that: Any): Boolean

The equals method for arbitrary sequences. Compares this sequence to some other object.

  • that
    • The object to compare the sequence to
  • returns
    • true if that is a sequence that has the same elements as this sequence in the same order, false otherwise
  • Definition Classes
    • ListBuffer → GenSeqLike → Equals → AnyRef → Any

(defined at scala.collection.mutable.ListBuffer)

def insertAll(n: Int, seq: collection.Traversable[A]): Unit

Inserts new elements at the index n . Opposed to method update , this method will not replace an element with a new one. Instead, it will insert a new element at index n .

  • n
    • the index where a new element will be inserted.
  • seq
    • the iterable object providing all elements to insert.
  • Definition Classes
    • ListBuffer → BufferLike
  • Exceptions thrown
    • IndexOutOfBoundsException if n is out of bounds.

(defined at scala.collection.mutable.ListBuffer)

def prependToList(xs: immutable.List[A]): immutable.List[A]

Prepends the elements of this buffer to a given list

  • xs
    • the list to which elements are prepended

(defined at scala.collection.mutable.ListBuffer)

def remove(n: Int): A

Removes the element on a given index position. May take time linear in the buffer size.

  • n
    • the index which refers to the element to delete.
  • returns
    • n the element that was formerly at position n .
  • Definition Classes
    • ListBuffer → BufferLike
  • Exceptions thrown
    • IndexOutOfBoundsException if n is out of bounds.
  • Note
    • an element must exists at position n .

(defined at scala.collection.mutable.ListBuffer)

def remove(n: Int, count: Int): Unit

Removes a given number of elements on a given index position. May take time linear in the buffer size.

  • n
    • the index which refers to the first element to remove.
  • count
    • the number of elements to remove.
  • Definition Classes
    • ListBuffer → BufferLike
  • Exceptions thrown
    • IllegalArgumentException if count < 0 . IndexOutOfBoundsException if the index n is not in the valid range 0 <= n <= length - count (with count > 0 ).

(defined at scala.collection.mutable.ListBuffer)

def result(): immutable.List[A]

Returns the accumulated List .

This method may be called multiple times to obtain snapshots of the list in different stages of construction.

  • returns
    • a collection containing the elements added to this builder.
  • Definition Classes
    • ListBuffer → ReusableBuilder → Builder

(defined at scala.collection.mutable.ListBuffer)

def toList: immutable.List[A]

Converts this buffer to a list. Takes constant time. The buffer is copied lazily, the first time it is mutated.

  • returns
    • a list containing all elements of this list buffer.
  • Definition Classes
    • ListBuffer → TraversableForwarder → TraversableOnce → GenTraversableOnce

(defined at scala.collection.mutable.ListBuffer)

def underlying: immutable.List[A]

The iterable object to which calls are forwarded

  • Attributes
    • protected
  • Definition Classes
    • ListBuffer → SeqForwarder → IterableForwarder → TraversableForwarder

(defined at scala.collection.mutable.ListBuffer)

def update(n: Int, x: A): Unit

Replaces element at index n with the new element newelem . Takes time linear in the buffer size. (except the first element, which is updated in constant time).

  • n
    • the index of the element to replace.
  • x
    • the new element.
  • Definition Classes
    • ListBuffer → BufferLike → SeqLike
  • Exceptions thrown
    • IndexOutOfBoundsException if n is out of bounds.

(defined at scala.collection.mutable.ListBuffer)

Value Members From scala.collection.mutable.Seq

def seq: Seq[A]

A version of this collection with all of the operations implemented sequentially (i.e., in a single-threaded manner).

This method returns a reference to this collection. In parallel collections, it is redefined to return a sequential implementation of this collection. In both cases, it has O(1) complexity.

  • returns
    • a sequential view of the collection.
  • Definition Classes
    • Seq → Seq → GenSeq → GenSeqLike → Iterable → Iterable → GenIterable → Traversable → Traversable → GenTraversable → Parallelizable → TraversableOnce → GenTraversableOnce

(defined at scala.collection.mutable.Seq)

Value Members From scala.collection.mutable.SeqLike

def parCombiner: Combiner[A, ParSeq[A]]

The default par implementation uses the combiner provided by this method to create a new parallel collection.

  • returns
    • a combiner for the parallel collection of type ParRepr
  • Attributes
    • protected[this]
  • Definition Classes
    • SeqLike → SeqLike → TraversableLike → Parallelizable

(defined at scala.collection.mutable.SeqLike)

def transform(f: (A) ⇒ A): ListBuffer.this.type

Applies a transformation function to all values contained in this sequence. The transformation function produces new values from existing elements.

  • f
    • the transformation to apply
  • returns
    • the sequence itself.
  • Definition Classes
    • SeqLike

(defined at scala.collection.mutable.SeqLike)


Value Members From Implicit scala.collection.parallel.CollectionsHaveToParArray ——————————————————————————–

def toParArray: ParArray[T]

  • Implicit information
    • This member is added by an implicit conversion from ListBuffer [A] to CollectionsHaveToParArray [ListBuffer [A], T] performed by method CollectionsHaveToParArray in scala.collection.parallel. This conversion will take place only if an implicit value of type (ListBuffer [A]) ⇒ GenTraversableOnce [T] is in scope.
  • Definition Classes
    • CollectionsHaveToParArray (added by implicit convertion: scala.collection.parallel.CollectionsHaveToParArray)

Full Source:

/*                     __                                               *\
**     ________ ___   / /  ___     Scala API                            **
**    / __/ __// _ | / /  / _ |    (c) 2003-2013, LAMP/EPFL             **
**  __\ \/ /__/ __ |/ /__/ __ |    http://scala-lang.org/               **
** /____/\___/_/ |_/____/_/ | |                                         **
**                          |/                                          **
\*                                                                      */

package scala
package collection
package mutable

import generic._
import immutable.{List, Nil, ::}
import java.io.{ObjectOutputStream, ObjectInputStream}

/** A `Buffer` implementation backed by a list. It provides constant time
 *  prepend and append. Most other operations are linear.
 *
 *  @author  Matthias Zenger
 *  @author  Martin Odersky
 *  @version 2.8
 *  @since   1
 *  @see [[http://docs.scala-lang.org/overviews/collections/concrete-mutable-collection-classes.html#list_buffers "Scala's Collection Library overview"]]
 *  section on `List Buffers` for more information.
 *
 *  @tparam A    the type of this list buffer's elements.
 *
 *  @define Coll `ListBuffer`
 *  @define coll list buffer
 *  @define thatinfo the class of the returned collection. In the standard library configuration,
 *    `That` is always `ListBuffer[B]` because an implicit of type `CanBuildFrom[ListBuffer, B, ListBuffer[B]]`
 *    is defined in object `ListBuffer`.
 *  @define bfinfo an implicit value of class `CanBuildFrom` which determines the
 *    result class `That` from the current representation type `Repr`
 *    and the new element type `B`. This is usually the `canBuildFrom` value
 *    defined in object `ListBuffer`.
 *  @define orderDependent
 *  @define orderDependentFold
 *  @define mayNotTerminateInf
 *  @define willNotTerminateInf
 */
@SerialVersionUID(3419063961353022662L)
final class ListBuffer[A]
      extends AbstractBuffer[A]
         with Buffer[A]
         with GenericTraversableTemplate[A, ListBuffer]
         with BufferLike[A, ListBuffer[A]]
         with ReusableBuilder[A, List[A]]
         with SeqForwarder[A]
         with Serializable
{
  override def companion: GenericCompanion[ListBuffer] = ListBuffer

  import scala.collection.Traversable
  import scala.collection.immutable.ListSerializeEnd

  /** Expected invariants:
   *  If start.isEmpty, last0 == null
   *  If start.nonEmpty, last0 != null
   *  If len == 0, start.isEmpty
   *  If len > 0, start.nonEmpty
   */
  private var start: List[A] = Nil
  private var last0: ::[A] = _
  private var exported: Boolean = false
  private var len = 0

  protected def underlying: List[A] = start

  private def writeObject(out: ObjectOutputStream) {
    // write start
    var xs: List[A] = start
    while (!xs.isEmpty) { out.writeObject(xs.head); xs = xs.tail }
    out.writeObject(ListSerializeEnd)

    // no need to write last0

    // write if exported
    out.writeBoolean(exported)

    // write the length
    out.writeInt(len)
  }

  private def readObject(in: ObjectInputStream) {
    // read start, set last0 appropriately
    var elem: A = in.readObject.asInstanceOf[A]
    if (elem == ListSerializeEnd) {
      start = Nil
      last0 = null
    } else {
      var current = new ::(elem, Nil)
      start = current
      elem = in.readObject.asInstanceOf[A]
      while (elem != ListSerializeEnd) {
        val list = new ::(elem, Nil)
        current.tl = list
        current = list
        elem = in.readObject.asInstanceOf[A]
      }
      last0 = current
      start
    }

    // read if exported
    exported = in.readBoolean()

    // read the length
    len = in.readInt()
  }

  /** The current length of the buffer.
   *
   *  This operation takes constant time.
   */
  override def length = len

  // Don't use the inherited size, which forwards to a List and is O(n).
  override def size = length

  // Implementations of abstract methods in Buffer

  override def apply(n: Int): A =
    if (n < 0 || n >= len) throw new IndexOutOfBoundsException(n.toString())
    else super.apply(n)

  /** Replaces element at index `n` with the new element
   *  `newelem`. Takes time linear in the buffer size. (except the
   *  first element, which is updated in constant time).
   *
   *  @param n  the index of the element to replace.
   *  @param x  the new element.
   *  @throws IndexOutOfBoundsException if `n` is out of bounds.
   */
  def update(n: Int, x: A) {
    // We check the bounds early, so that we don't trigger copying.
    if (n < 0 || n >= len) throw new IndexOutOfBoundsException(n.toString)
    if (exported) copy()
    if (n == 0) {
      val newElem = new :: (x, start.tail)
      if (last0 eq start) {
        last0 = newElem
      }
      start = newElem
    } else {
      var cursor = start
      var i = 1
      while (i < n) {
        cursor = cursor.tail
        i += 1
      }
      val newElem = new :: (x, cursor.tail.tail)
      if (last0 eq cursor.tail) {
        last0 = newElem
      }
      cursor.asInstanceOf[::[A]].tl = newElem
    }
  }

  /** Appends a single element to this buffer. This operation takes constant time.
   *
   *  @param x  the element to append.
   *  @return   this $coll.
   */
  def += (x: A): this.type = {
    if (exported) copy()
    if (isEmpty) {
      last0 = new :: (x, Nil)
      start = last0
    } else {
      val last1 = last0
      last0 = new :: (x, Nil)
      last1.tl = last0
    }
    len += 1
    this
  }

  override def ++=(xs: TraversableOnce[A]): this.type = xs match {
    case x: AnyRef if x eq this      => this ++= (this take size)
    case _                           => super.++=(xs)

  }

  override def ++=:(xs: TraversableOnce[A]): this.type =
    if (xs.asInstanceOf[AnyRef] eq this) ++=: (this take size) else super.++=:(xs)

  /** Clears the buffer contents.
   */
  def clear() {
    start = Nil
    last0 = null
    exported = false
    len = 0
  }

  /** Prepends a single element to this buffer. This operation takes constant
   *  time.
   *
   *  @param x  the element to prepend.
   *  @return   this $coll.
   */
  def +=: (x: A): this.type = {
    if (exported) copy()
    val newElem = new :: (x, start)
    if (isEmpty) last0 = newElem
    start = newElem
    len += 1
    this
  }

  /** Inserts new elements at the index `n`. Opposed to method
   *  `update`, this method will not replace an element with a new
   *  one. Instead, it will insert a new element at index `n`.
   *
   *  @param  n     the index where a new element will be inserted.
   *  @param  seq   the iterable object providing all elements to insert.
   *  @throws IndexOutOfBoundsException if `n` is out of bounds.
   */
  def insertAll(n: Int, seq: Traversable[A]) {
    // We check the bounds early, so that we don't trigger copying.
    if (n < 0 || n > len) throw new IndexOutOfBoundsException(n.toString)
    if (exported) copy()
    var elems = seq.toList.reverse
    len += elems.length
    if (n == 0) {
      while (!elems.isEmpty) {
        val newElem = new :: (elems.head, start)
        if (start.isEmpty) last0 = newElem
        start = newElem
        elems = elems.tail
      }
    } else {
      var cursor = start
      var i = 1
      while (i < n) {
        cursor = cursor.tail
        i += 1
      }
      while (!elems.isEmpty) {
        val newElem = new :: (elems.head, cursor.tail)
        if (cursor.tail.isEmpty) last0 = newElem
        cursor.asInstanceOf[::[A]].tl = newElem
        elems = elems.tail
      }
    }
  }

  /** Reduce the length of the buffer, and null out last0
   *  if this reduces the length to 0.
   */
  private def reduceLengthBy(num: Int) {
    len -= num
    if (len <= 0)   // obviously shouldn't be < 0, but still better not to leak
      last0 = null
  }

  /** Removes a given number of elements on a given index position. May take
   *  time linear in the buffer size.
   *
   *  @param n         the index which refers to the first element to remove.
   *  @param count     the number of elements to remove.
   *  @throws   IndexOutOfBoundsException if the index `n` is not in the valid range
   *            `0 <= n <= length - count` (with `count > 0`).
   *  @throws   IllegalArgumentException if `count < 0`.
   */
  override def remove(n: Int, count: Int) {
    if (count < 0) throw new IllegalArgumentException("removing negative number of elements: " + count.toString)
    else if (count == 0) return  // Nothing to do
    if (n < 0 || n > len - count) throw new IndexOutOfBoundsException("at " + n.toString + " deleting " + count.toString)
    if (exported) copy()
    val n1 = n max 0
    val count1 = count min (len - n1)
    if (n1 == 0) {
      var c = count1
      while (c > 0) {
        start = start.tail
        c -= 1
      }
    } else {
      var cursor = start
      var i = 1
      while (i < n1) {
        cursor = cursor.tail
        i += 1
      }
      var c = count1
      while (c > 0) {
        if (last0 eq cursor.tail) last0 = cursor.asInstanceOf[::[A]]
        cursor.asInstanceOf[::[A]].tl = cursor.tail.tail
        c -= 1
      }
    }
    reduceLengthBy(count1)
  }

// Implementation of abstract method in Builder

  /** Returns the accumulated `List`.
   *
   *  This method may be called multiple times to obtain snapshots of the list in different stages of construction.
   */
  def result: List[A] = toList

  /** Converts this buffer to a list. Takes constant time. The buffer is
   *  copied lazily, the first time it is mutated.
   */
  override def toList: List[A] = {
    exported = !isEmpty
    start
  }

// New methods in ListBuffer

  /** Prepends the elements of this buffer to a given list
   *
   *  @param xs   the list to which elements are prepended
   */
  def prependToList(xs: List[A]): List[A] = {
    if (isEmpty) xs
    else {
      if (exported) copy()
      last0.tl = xs
      toList
    }
  }

// Overrides of methods in Buffer

  /** Removes the element on a given index position. May take time linear in
   *  the buffer size.
   *
   *  @param  n  the index which refers to the element to delete.
   *  @return n  the element that was formerly at position `n`.
   *  @note      an element must exists at position `n`.
   *  @throws IndexOutOfBoundsException if `n` is out of bounds.
   */
  def remove(n: Int): A = {
    if (n < 0 || n >= len) throw new IndexOutOfBoundsException(n.toString())
    if (exported) copy()
    var old = start.head
    if (n == 0) {
      start = start.tail
    } else {
      var cursor = start
      var i = 1
      while (i < n) {
        cursor = cursor.tail
        i += 1
      }
      old = cursor.tail.head
      if (last0 eq cursor.tail) last0 = cursor.asInstanceOf[::[A]]
      cursor.asInstanceOf[::[A]].tl = cursor.tail.tail
    }
    reduceLengthBy(1)
    old
  }

  /** Remove a single element from this buffer. May take time linear in the
   *  buffer size.
   *
   *  @param elem  the element to remove.
   *  @return      this $coll.
   */
  override def -= (elem: A): this.type = {
    if (exported) copy()
    if (isEmpty) {}
    else if (start.head == elem) {
      start = start.tail
      reduceLengthBy(1)
    }
    else {
      var cursor = start
      while (!cursor.tail.isEmpty && cursor.tail.head != elem) {
        cursor = cursor.tail
      }
      if (!cursor.tail.isEmpty) {
        val z = cursor.asInstanceOf[::[A]]
        if (z.tl == last0)
          last0 = z
        z.tl = cursor.tail.tail
        reduceLengthBy(1)
      }
    }
    this
  }

  /** Returns an iterator over this `ListBuffer`.  The iterator will reflect
   *  changes made to the underlying `ListBuffer` beyond the next element;
   *  the next element's value is cached so that `hasNext` and `next` are
   *  guaranteed to be consistent.  In particular, an empty `ListBuffer`
   *  will give an empty iterator even if the `ListBuffer` is later filled.
   */
  override def iterator: Iterator[A] = new AbstractIterator[A] {
    // Have to be careful iterating over mutable structures.
    // This used to have "(cursor ne last0)" as part of its hasNext
    // condition, which means it can return true even when the iterator
    // is exhausted.  Inconsistent results are acceptable when one mutates
    // a structure while iterating, but we should never return hasNext == true
    // on exhausted iterators (thus creating exceptions) merely because
    // values were changed in-place.
    var cursor: List[A] = if (ListBuffer.this.isEmpty) Nil else start

    def hasNext: Boolean = cursor ne Nil
    def next(): A =
      if (!hasNext) throw new NoSuchElementException("next on empty Iterator")
      else {
        val ans = cursor.head
        cursor = cursor.tail
        ans
      }
  }

  // Private methods

  /** Copy contents of this buffer */
  private def copy() {
    if (isEmpty) return
    var cursor = start
    val limit = last0.tail
    clear()
    while (cursor ne limit) {
      this += cursor.head
      cursor = cursor.tail
    }
  }

  override def equals(that: Any): Boolean = that match {
    case that: ListBuffer[_] => this.start equals that.start
    case _                   => super.equals(that)
  }

  /** Returns a clone of this buffer.
   *
   *  @return a `ListBuffer` with the same elements.
   */
  override def clone(): ListBuffer[A] = (new ListBuffer[A]) ++= this

  /** Defines the prefix of the string representation.
   *
   *  @return the string representation of this buffer.
   */
  override def stringPrefix: String = "ListBuffer"
}

/** $factoryInfo
 *  @define Coll `ListBuffer`
 *  @define coll list buffer
 */
object ListBuffer extends SeqFactory[ListBuffer] {
  implicit def canBuildFrom[A]: CanBuildFrom[Coll, A, ListBuffer[A]] = ReusableCBF.asInstanceOf[GenericCanBuildFrom[A]]
  def newBuilder[A]: Builder[A, ListBuffer[A]] = new GrowingBuilder(new ListBuffer[A])
}