Scala Standard Library2.12.2 < Back
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# Packages

-  package root

  This is the documentation for the Scala standard library.

  This is the documentation for the Scala standard library.

  #### Package structure

  The scala package contains core types like `Int`, `Float`, `Array` or `Option` which are accessible in all Scala compilation units without explicit qualification or imports.

  Notable packages include:

  - `scala.collection` and its sub-packages contain Scala's collections framework
    - `scala.collection.immutable` - Immutable, sequential data-structures such as `Vector`, `List`, `Range`, `HashMap` or `HashSet`
    - `scala.collection.mutable` - Mutable, sequential data-structures such as `ArrayBuffer`, `StringBuilder`, `HashMap` or `HashSet`
    - `scala.collection.concurrent` - Mutable, concurrent data-structures such as `TrieMap`
    - `scala.collection.parallel.immutable` - Immutable, parallel data-structures such as `ParVector`, `ParRange`, `ParHashMap` or `ParHashSet`
    - `scala.collection.parallel.mutable` - Mutable, parallel data-structures such as `ParArray`, `ParHashMap`, `ParTrieMap` or `ParHashSet`
  - `scala.concurrent` - Primitives for concurrent programming such as `Futures` and `Promises`
  - `scala.io` - Input and output operations
  - `scala.math` - Basic math functions and additional numeric types like `BigInt` and `BigDecimal`
  - `scala.sys` - Interaction with other processes and the operating system
  - `scala.util.matching` - Regular expressions

  Other packages exist. See the complete list on the right.

  Additional parts of the standard library are shipped as separate libraries. These include:

  - `scala.reflect` - Scala's reflection API (scala-reflect.jar)
  - `scala.xml` - XML parsing, manipulation, and serialization (scala-xml.jar)
  - `scala.swing` - A convenient wrapper around Java's GUI framework called Swing (scala-swing.jar)
  - `scala.util.parsing` - Parser combinators (scala-parser-combinators.jar)

  #### Automatic imports

  Identifiers in the scala package and the `scala.Predef` object are always in scope by default.

  Some of these identifiers are type aliases provided as shortcuts to commonly used classes. For example, `List` is an alias for `scala.collection.immutable.List`.

  Other aliases refer to classes provided by the underlying platform. For example, on the JVM, `String` is an alias for `java.lang.String`.

  Definition Classes
    root
-  package scala

  Core Scala types.

  Core Scala types. They are always available without an explicit import.

  Definition Classes
    root
-  package collection

  Contains the base traits and objects needed to use and extend Scala's collection library.

  Contains the base traits and objects needed to use and extend Scala's collection library.

  #### Guide

  A detailed guide for using the collections library is available at http://docs.scala-lang.org/overviews/collections/introduction.html. Developers looking to extend the collections library can find a description of its architecture at http://docs.scala-lang.org/overviews/core/architecture-of-scala-collections.html.

  #### Using Collections

  It is convenient to treat all collections as either a scala.collection.Traversable or scala.collection.Iterable, as these traits define the vast majority of operations on a collection.

  Collections can, of course, be treated as specifically as needed, and the library is designed to ensure that the methods that transform collections will return a collection of the same type:

      scala> val array = Array(1,2,3,4,5,6)
      array: Array[Int] = Array(1, 2, 3, 4, 5, 6)

      scala> array map { _.toString }
      res0: Array[String] = Array(1, 2, 3, 4, 5, 6)

      scala> val list = List(1,2,3,4,5,6)
      list: List[Int] = List(1, 2, 3, 4, 5, 6)

      scala> list map { _.toString }
      res1: List[String] = List(1, 2, 3, 4, 5, 6)

  #### Creating Collections

  The most common way to create a collection is to use its companion object as a factory. The three most commonly used collections are scala.collection.Seq, scala.collection.immutable.Set, and scala.collection.immutable.Map. They can be used directly as shown below since their companion objects are all available as type aliases in either the scala package or in `scala.Predef`. New collections are created like this:

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

      scala> val set = Set(1,2,3,4,1)
      set: scala.collection.immutable.Set[Int] = Set(1, 2, 3, 4)

      scala> val map = Map(1 -> "one", 2 -> "two", 3 -> "three", 2 -> "too")
      map: scala.collection.immutable.Map[Int,String] = Map(1 -> one, 2 -> too, 3 -> three)

  It is also typical to prefer the scala.collection.immutable collections over those in scala.collection.mutable; the types aliased in the `scala.Predef` object are the immutable versions.

  Also note that the collections library was carefully designed to include several implementations of each of the three basic collection types. These implementations have specific performance characteristics which are described in the guide.

  The concrete parallel collections also have specific performance characteristics which are described in the parallel collections guide

  ##### Converting to and from Java Collections

  The scala.collection.JavaConverters object provides a collection of decorators that allow converting between Scala and Java collections using `asScala` and `asJava` methods.

  Definition Classes
    scala
-  package concurrent
  Definition Classes
    collection
-  package convert
  Definition Classes
    collection
-  package generic
  Definition Classes
    collection
-  package immutable
  Definition Classes
    collection
-  package mutable
  Definition Classes
    collection
- AbstractBuffer
- AbstractIterable
- AbstractMap
- AbstractSeq
- AbstractSet
- AbstractSortedMap
- AbstractSortedSet
- AnyRefMap
- ArrayBuffer
- ArrayBuilder
- ArrayLike
- ArrayOps
- ArraySeq
- ArrayStack
- BitSet
- Buffer
- BufferLike
- BufferProxy
- Builder
- Cloneable
- DefaultEntry
- DefaultMapModel
- DoubleLinkedList
- DoubleLinkedListLike
- FlatHashTable
- GrowingBuilder
- HashEntry
- HashMap
- HashSet
- HashTable
- History
- ImmutableMapAdaptor
- ImmutableSetAdaptor
- IndexedSeq
- IndexedSeqLike
- IndexedSeqOptimized
- IndexedSeqView
- Iterable
- LazyBuilder
- LinearSeq
- LinkedEntry
- LinkedHashMap
- LinkedHashSet
- LinkedList
- LinkedListLike
- ListBuffer
- ListMap
- LongMap
- Map
- MapBuilder
- MapLike
- MapProxy
- MultiMap
- MutableList
- ObservableBuffer
- ObservableMap
- ObservableSet
- OpenHashMap
- PriorityQueue
- PriorityQueueProxy
- Publisher
- Queue
- QueueProxy
- ResizableArray
- ReusableBuilder
- RevertibleHistory
- Seq
- SeqLike
- Set
- SetBuilder
- SetLike
- SetProxy
- SortedMap
- SortedSet
- Stack
- StackProxy
- StringBuilder
- Subscriber
- SynchronizedBuffer
- SynchronizedMap
- SynchronizedPriorityQueue
- SynchronizedQueue
- SynchronizedSet
- SynchronizedStack
- Traversable
- TreeMap
- TreeSet
- Undoable
- UnrolledBuffer
- WeakHashMap
- WrappedArray
- WrappedArrayBuilder
-  package parallel

  Package object for parallel collections.

  Package object for parallel collections.

  Definition Classes
    collection
-  package script
  Definition Classes
    collection

p

scala.collection

# mutable 

#### package mutable

Content Hierarchy
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1. Alphabetic

Visibility

1. Public
2. All

### Type Members

1.  abstract class AbstractBuffer [A] extends AbstractSeq[A] with Buffer[A]

   Explicit instantiation of the `Buffer` trait to reduce class file size in subclasses.

2.  abstract class AbstractIterable [A] extends collection.AbstractIterable[A] with Iterable[A]

   Explicit instantiation of the `Iterable` trait to reduce class file size in subclasses.

3.  abstract class AbstractMap [K, V] extends collection.AbstractMap[K, V] with Map[K, V]

   Explicit instantiation of the `Map` trait to reduce class file size in subclasses.

4.  abstract class AbstractSeq [A] extends collection.AbstractSeq[A] with Seq[A]

   Explicit instantiation of the `Seq` trait to reduce class file size in subclasses.

5.  abstract class AbstractSet [A] extends AbstractIterable[A] with Set[A]

   Explicit instantiation of the `Set` trait to reduce class file size in subclasses.

6.  abstract class AbstractSortedMap [A, B] extends AbstractMap[A, B] with SortedMap[A, B]

   Explicit instantiation of the `SortedMap` trait to reduce class file size in subclasses.

7.  abstract class AbstractSortedSet [A] extends AbstractSet[A] with SortedSet[A]

   Explicit instantiation of the `SortedSet` trait to reduce class file size in subclasses.

8.  final class AnyRefMap [K <: AnyRef, V] extends AbstractMap[K, V] with Map[K, V] with MapLike[K, V, AnyRefMap[K, V]] with Serializable

   This class implements mutable maps with `AnyRef` keys based on a hash table with open addressing.

   This class implements mutable maps with `AnyRef` keys based on a hash table with open addressing.

   Basic map operations on single entries, including `contains` and `get`, are typically significantly faster with `AnyRefMap` than HashMap. Note that numbers and characters are not handled specially in AnyRefMap; only plain `equals` and `hashCode` are used in comparisons.

   Methods that traverse or regenerate the map, including `foreach` and `map`, are not in general faster than with `HashMap`. The methods `foreachKey`, `foreachValue`, `mapValuesNow`, and `transformValues` are, however, faster than alternative ways to achieve the same functionality.

   Maps with open addressing may become less efficient at lookup after repeated addition/removal of elements. Although `AnyRefMap` makes a decent attempt to remain efficient regardless, calling `repack` on a map that will no longer have elements removed but will be used heavily may save both time and storage space.

   This map is not intended to contain more than 229 entries (approximately 500 million). The maximum capacity is 230, but performance will degrade rapidly as 230 is approached.

   Annotations
     @SerialVersionUID()
9.  class ArrayBuffer [A] extends AbstractBuffer[A] with Buffer[A] with GenericTraversableTemplate[A, ArrayBuffer] with BufferLike[A, ArrayBuffer[A]] with IndexedSeqOptimized[A, ArrayBuffer[A]] with Builder[A, ArrayBuffer[A]] with ResizableArray[A] with CustomParallelizable[A, ParArray[A]] with Serializable

   An implementation of the `Buffer` class using an array to represent the assembled sequence internally.

   An implementation of the `Buffer` class using an array to represent the assembled sequence internally. Append, update and random access take constant time (amortized time). Prepends and removes are linear in the buffer size.

   A

     the type of this arraybuffer's elements.

   Annotations
     @SerialVersionUID()
   Version

     2.8

   Since

     1

   See also

     "Scala's Collection Library overview" section on `Array Buffers` for more information.

10.  abstract class ArrayBuilder [T] extends ReusableBuilder[T, Array[T]] with Serializable

    A builder class for arrays.

    A builder class for arrays.

    T

      the type of the elements for the builder.

    Since

      2.8

11.  trait ArrayLike [A, +Repr] extends IndexedSeqOptimized[A, Repr]

    A common supertrait of `ArrayOps` and `WrappedArray` that factors out the `deep` method for arrays and wrapped arrays and serves as a marker trait for array wrappers.

    A common supertrait of `ArrayOps` and `WrappedArray` that factors out the `deep` method for arrays and wrapped arrays and serves as a marker trait for array wrappers.

    A

      type of the elements contained in the array like object.

    Repr

      the type of the actual collection containing the elements.

12.  sealed trait ArrayOps [T] extends ArrayLike[T, Array[T]] with CustomParallelizable[T, ParArray[T]]

    This class serves as a wrapper for `Array`s with all the operations found in indexed sequences.

    This class serves as a wrapper for `Array`s with all the operations found in indexed sequences. Where needed, instances of arrays are implicitly converted into this class.

    The difference between this class and `WrappedArray` is that calling transformer methods such as `filter` and `map` will yield an array, whereas a `WrappedArray` will remain a `WrappedArray`.

    T

      type of the elements contained in this array.

    Since

      2.8

13.  class ArraySeq [A] extends AbstractSeq[A] with IndexedSeq[A] with GenericTraversableTemplate[A, ArraySeq] with IndexedSeqOptimized[A, ArraySeq[A]] with CustomParallelizable[A, ParArray[A]] with Serializable

    A class for polymorphic arrays of elements that's represented internally by an array of objects.

    A class for polymorphic arrays of elements that's represented internally by an array of objects. This means that elements of primitive types are boxed.

    A

      type of the elements contained in this array sequence.

    Annotations
      @SerialVersionUID()
    Version

      2.8

    Since

      2.8

    See also

      "Scala's Collection Library overview" section on `Array Sequences` for more information.

14.  class ArrayStack [T] extends AbstractSeq[T] with IndexedSeq[T] with IndexedSeqLike[T, ArrayStack[T]] with GenericTraversableTemplate[T, ArrayStack] with IndexedSeqOptimized[T, ArrayStack[T]] with Cloneable[ArrayStack[T]] with Builder[T, ArrayStack[T]] with Serializable

    Simple stack class backed by an array.

    Simple stack class backed by an array. Should be significantly faster than the standard mutable stack.

    T

      type of the elements contained in this array stack.

    Annotations
      @SerialVersionUID()
    Since

      2.7

    See also

      "Scala's Collection Library overview" section on `Array Stacks` for more information.

15.  class BitSet extends AbstractSet[Int] with SortedSet[Int] with collection.BitSet with BitSetLike[BitSet] with SetLike[Int, BitSet] with Serializable

    A class for mutable bitsets.

    A class for mutable bitsets.

    Bitsets are sets of non-negative integers which are represented as variable-size arrays of bits packed into 64-bit words. The memory footprint of a bitset is determined by the largest number stored in it.

    Annotations
      @SerialVersionUID()
    See also

      "Scala's Collection Library overview" section on `Mutable Bitsets` for more information.

16.  trait Buffer [A] extends Seq[A] with GenericTraversableTemplate[A, Buffer] with BufferLike[A, Buffer[A]] with scala.Cloneable

    Buffers are used to create sequences of elements incrementally by appending, prepending, or inserting new elements.

    Buffers are used to create sequences of elements incrementally by appending, prepending, or inserting new elements. It is also possible to access and modify elements in a random access fashion via the index of the element in the current sequence.

    A

      type of the elements contained in this buffer.

    Version

      2.8

    Since

      1

17.  trait BufferLike [A, +This <: BufferLike[A, This] with Buffer[A]] extends Growable[A] with Shrinkable[A] with Scriptable[A] with Subtractable[A, This] with SeqLike[A, This] with scala.Cloneable

    A template trait for buffers of type `Buffer[A]`.

    A template trait for buffers of type `Buffer[A]`.

    Buffers are used to create sequences of elements incrementally by appending, prepending, or inserting new elements. It is also possible to access and modify elements in a random access fashion via the index of the element in the current sequence.

    A

      the type of the elements of the buffer

    This

      the type of the buffer itself.

    Version

      2.8

    Since

      2.8

    Note

      This trait provides most of the operations of a `Buffer` independently of its representation. It is typically inherited by concrete implementations of buffers. To implement a concrete buffer, you need to provide implementations of the following methods:

          def apply(idx: Int): A
          def update(idx: Int, elem: A)
          def length: Int
          def clear()
          def +=(elem: A): this.type
          def +=:(elem: A): this.type
          def insertAll(n: Int, iter: Traversable[A])
          def remove(n: Int): A

18.  trait Builder [-Elem, +To] extends Growable[Elem]

    The base trait of all builders.

    The base trait of all builders. A builder lets one construct a collection incrementally, by adding elements to the builder with `+=` and then converting to the required collection type with `result`.

    One cannot assume that a single `Builder` can build more than one instance of the desired collection. Particular subclasses may allow such behavior. Otherwise, `result` should be treated as a terminal operation: after it is called, no further methods should be called on the builder. Extend the collection.mutable.ReusableBuilder trait instead of `Builder` for builders that may be reused to build multiple instances.

    Elem

      the type of elements that get added to the builder.

    To

      the type of collection that it produced.

    Since

      2.8

19.  trait Cloneable [+A <: AnyRef] extends scala.Cloneable

    A trait for cloneable collections.

    A trait for cloneable collections.

    A

      Type of the elements contained in the collection, covariant and with reference types as upperbound.

    Since

      2.8

20.  final class DefaultEntry [A, B] extends HashEntry[A, DefaultEntry[A, B]] with Serializable

    Class used internally for default map model.

    Class used internally for default map model.

    Since

      2.3

21.  trait FlatHashTable [A] extends HashUtils[A]

    An implementation class backing a `HashSet`.

    An implementation class backing a `HashSet`.

    This trait is used internally. It can be mixed in with various collections relying on hash table as an implementation.

22.  class GrowingBuilder [Elem, To <: Growable[Elem]] extends Builder[Elem, To]

    The canonical builder for collections that are growable, i.e.

    The canonical builder for collections that are growable, i.e. that support an efficient `+=` method which adds an element to the collection.

    GrowableBuilders can produce only a single instance of the collection they are growing.

    Version

      2.8

    Since

      2.8

23.  trait HashEntry [A, E] extends AnyRef

    Class used internally.

    Class used internally.

    Since

      2.8

24.  class HashMap [A, B] extends AbstractMap[A, B] with Map[A, B] with MapLike[A, B, HashMap[A, B]] with HashTable[A, DefaultEntry[A, B]] with CustomParallelizable[(A, B), ParHashMap[A, B]] with Serializable

    This class implements mutable maps using a hashtable.

    This class implements mutable maps using a hashtable.

    A

      the type of the keys contained in this hash map.

    B

      the type of the values assigned to keys in this hash map.

    Annotations
      @SerialVersionUID()
    Since

      1

    See also

      "Scala's Collection Library overview" section on `Hash Tables` for more information.

25.  class HashSet [A] extends AbstractSet[A] with Set[A] with GenericSetTemplate[A, HashSet] with SetLike[A, HashSet[A]] with FlatHashTable[A] with CustomParallelizable[A, ParHashSet[A]] with Serializable

    This class implements mutable sets using a hashtable.

    This class implements mutable sets using a hashtable.

    Annotations
      @SerialVersionUID()
    Version

      2.0, 31/12/2006

    Since

      1

    See also

      "Scala's Collection Library overview" section on `Hash Tables` for more information.

26.  trait HashTable [A, Entry >: Null <: HashEntry[A, Entry]] extends HashUtils[A]

    This class can be used to construct data structures that are based on hashtables.

    This class can be used to construct data structures that are based on hashtables. Class `HashTable[A]` implements a hashtable that maps keys of type `A` to values of the fully abstract member type `Entry`. Classes that make use of `HashTable` have to provide an implementation for `Entry`.

    There are mainly two parameters that affect the performance of a hashtable: the initial size and the load factor. The size refers to the number of buckets in the hashtable, and the load factor is a measure of how full the hashtable is allowed to get before its size is automatically doubled. Both parameters may be changed by overriding the corresponding values in class `HashTable`.

    A

      type of the elements contained in this hash table.

    Version

      2.0, 31/12/2006

    Since

      1

27.  class History [Evt, Pub] extends AbstractIterable[(Pub, Evt)] with Subscriber[Evt, Pub] with Iterable[(Pub, Evt)] with Serializable

    `History[A, B]` objects may subscribe to events of type `A` published by an object of type `B`.

    `History[A, B]` objects may subscribe to events of type `A` published by an object of type `B`. The history subscriber object records all published events up to maximum number of `maxHistory` events.

    Evt

      Type of events.

    Pub

      Type of publishers.

    Annotations
      @SerialVersionUID()
    Version

      1.0, 08/07/2003

    Since

      1

28.  trait IndexedSeq [A] extends Seq[A] with collection.IndexedSeq[A] with GenericTraversableTemplate[A, IndexedSeq] with IndexedSeqLike[A, IndexedSeq[A]]

    A subtrait of `collection.IndexedSeq` which represents sequences that can be mutated.

29.  trait IndexedSeqLike [A, +Repr] extends collection.IndexedSeqLike[A, Repr]

    A subtrait of scala.collection.IndexedSeq which represents sequences that can be mutated.

    A subtrait of scala.collection.IndexedSeq which represents sequences that can be mutated.

    It declares a method `update` which allows updating an element at a specific index in the sequence.

    This trait just implements `iterator` in terms of `apply` and `length`. However, see `IndexedSeqOptimized` for an implementation trait that overrides operations to make them run faster under the assumption of fast random access with `apply`.

    A

      the element type of the mutable indexed sequence

    Repr

      the type of the actual mutable indexed sequence containing the elements.

30.  trait IndexedSeqOptimized [A, +Repr] extends IndexedSeqLike[A, Repr] with collection.IndexedSeqOptimized[A, Repr]

    A subtrait of scala.collection.IndexedSeq which represents sequences that can be mutated.

    A subtrait of scala.collection.IndexedSeq which represents sequences that can be mutated.

    Since

      2.8

31.  trait IndexedSeqView [A, +Coll] extends IndexedSeq[A] with IndexedSeqOptimized[A, IndexedSeqView[A, Coll]] with SeqView[A, Coll] with SeqViewLike[A, Coll, IndexedSeqView[A, Coll]]

    A non-strict view of a mutable `IndexedSeq`.

    A non-strict view of a mutable `IndexedSeq`.

    A view is a lazy version of some collection. Collection transformers such as `map` or `filter` or `++` do not traverse any elements when applied on a view. Instead they create a new view which simply records that fact that the operation needs to be applied. The collection elements are accessed, and the view operations are applied, when a non-view result is needed, or when the `force` method is called on a view. Some of the operations of this class will yield again a mutable indexed sequence, others will just yield a plain indexed sequence of type `collection.IndexedSeq`. Because this is a leaf class there is no associated `Like` class.

    A

      the element type of the view

    Coll

      the type of the underlying collection containing the elements.

    Version

      2.8

    Since

      2.8

32.  trait Iterable [A] extends Traversable[A] with collection.Iterable[A] with GenericTraversableTemplate[A, Iterable] with IterableLike[A, Iterable[A]] with Parallelizable[A, ParIterable[A]]

    A base trait for iterable collections that can be mutated.

    A base trait for iterable collections that can be mutated.

    This is a base trait for all mutable Scala collections that define an `iterator` method to step through one-by-one the collection's elements. Implementations of this trait need to provide a concrete method with signature:

        def iterator: Iterator[A]

    They also need to provide a method `newBuilder` which creates a builder for collections of the same kind.

    This trait implements `Iterable`'s `foreach` method by stepping through all elements using `iterator`. Subclasses should re-implement `foreach` with something more efficient, if possible.

    This trait adds methods `iterator`, `sameElements`, `takeRight`, `dropRight` to the methods inherited from trait `Traversable`.

    Note: This trait replaces every method that uses `break` in `TraversableLike` by an iterator version.

33.  abstract class LazyBuilder [Elem, +To] extends ReusableBuilder[Elem, To]

    A builder that constructs its result lazily.

    A builder that constructs its result lazily. Iterators or iterables to be added to this builder with `++=` are not evaluated until `result` is called.

    This builder can be reused.

    Elem

      type of the elements for this builder.

    To

      type of the collection this builder builds.

    Since

      2.8

34.  trait LinearSeq [A] extends Seq[A] with collection.LinearSeq[A] with GenericTraversableTemplate[A, LinearSeq] with LinearSeqLike[A, LinearSeq[A]]

    A subtrait of `collection.LinearSeq` which represents sequences that can be mutated.

    A subtrait of `collection.LinearSeq` which represents sequences that can be mutated.

    Linear sequences have reasonably efficient `head`, `tail`, and `isEmpty` methods. If these methods provide the fastest way to traverse the collection, a collection `Coll` that extends this trait should also extend `LinearSeqOptimized[A, Coll[A]]`.

35.  final class LinkedEntry [A, B] extends HashEntry[A, LinkedEntry[A, B]] with Serializable

    Class for the linked hash map entry, used internally.

    Class for the linked hash map entry, used internally.

    Since

      2.8

36.  class LinkedHashMap [A, B] extends AbstractMap[A, B] with Map[A, B] with MapLike[A, B, LinkedHashMap[A, B]] with HashTable[A, LinkedEntry[A, B]] with Serializable

    This class implements mutable maps using a hashtable.

    This class implements mutable maps using a hashtable. The iterator and all traversal methods of this class visit elements in the order they were inserted.

    A

      the type of the keys contained in this hash map.

    B

      the type of the values assigned to keys in this hash map.

    Annotations
      @SerialVersionUID()
37.  class LinkedHashSet [A] extends AbstractSet[A] with Set[A] with GenericSetTemplate[A, LinkedHashSet] with SetLike[A, LinkedHashSet[A]] with HashTable[A, Entry[A]] with Serializable

    This class implements mutable sets using a hashtable.

    This class implements mutable sets using a hashtable. The iterator and all traversal methods of this class visit elements in the order they were inserted.

    A

      the type of the elements contained in this set.

    Annotations
      @SerialVersionUID()
    Version

      2.0, 31/12/2006

    Since

      1

38.  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.

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

    A

      the type of this list buffer's elements.

    Annotations
      @SerialVersionUID()
    Version

      2.8

    Since

      1

    See also

      "Scala's Collection Library overview" section on `List Buffers` for more information.

39.  class ListMap [A, B] extends AbstractMap[A, B] with Map[A, B] with MapLike[A, B, ListMap[A, B]] with Serializable

    A simple mutable map backed by a list, so it preserves insertion order.

    A simple mutable map backed by a list, so it preserves insertion order.

    A

      the type of the keys contained in this list map.

    B

      the type of the values assigned to keys in this list map.

40.  final class LongMap [V] extends AbstractMap[Long, V] with Map[Long, V] with MapLike[Long, V, LongMap[V]] with Serializable

    This class implements mutable maps with `Long` keys based on a hash table with open addressing.

    This class implements mutable maps with `Long` keys based on a hash table with open addressing.

    Basic map operations on single entries, including `contains` and `get`, are typically substantially faster with `LongMap` than HashMap. Methods that act on the whole map, including `foreach` and `map` are not in general expected to be faster than with a generic map, save for those that take particular advantage of the internal structure of the map: `foreachKey`, `foreachValue`, `mapValuesNow`, and `transformValues`.

    Maps with open addressing may become less efficient at lookup after repeated addition/removal of elements. Although `LongMap` makes a decent attempt to remain efficient regardless, calling `repack` on a map that will no longer have elements removed but will be used heavily may save both time and storage space.

    This map is not intended to contain more than 229 entries (approximately 500 million). The maximum capacity is 230, but performance will degrade rapidly as 2^30 is approached.

41.  trait Map [K, V] extends Iterable[(K, V)] with collection.Map[K, V] with MapLike[K, V, Map[K, V]]

    A base trait for maps that can be mutated.

    A base trait for maps that can be mutated.

    Implementation note: This trait provides most of the operations of a mutable `Map` independently of its representation. It is typically inherited by concrete implementations of maps.

    To implement a concrete mutable map, you need to provide implementations of the following methods:

        def get(key: K): Option[V]
        def iterator: Iterator[(K, V)]
        def += (kv: (K, V)): This
        def -= (key: K): This

    If you wish that methods like `take`, `drop`, `filter` also return the same kind of map you should also override:

        def empty: This

    It is also good idea to override methods `foreach` and `size` for efficiency.

    Since

      1.0

42.  class MapBuilder [A, B, Coll <: GenMap[A, B] with GenMapLike[A, B, Coll]] extends ReusableBuilder[(A, B), Coll]

    The canonical builder for immutable maps, working with the map's `+` method to add new elements.

    The canonical builder for immutable maps, working with the map's `+` method to add new elements. Collections are built from their `empty` element using this + method.

    A

      Type of the keys for the map this builder creates.

    B

      Type of the values for the map this builder creates.

    Coll

      The type of the actual collection this builder builds.

    Since

      2.8

43.  trait MapLike [K, V, +This <: MapLike[K, V, This] with Map[K, V]] extends collection.MapLike[K, V, This] with Builder[(K, V), This] with Growable[(K, V)] with Shrinkable[K] with Cloneable[This] with Parallelizable[(K, V), ParMap[K, V]]

    A template trait for mutable maps.

    A template trait for mutable maps.

    Implementation note: This trait provides most of the operations of a mutable `Map` independently of its representation. It is typically inherited by concrete implementations of maps.

    To implement a concrete mutable map, you need to provide implementations of the following methods:

        def get(key: K): Option[V]
        def iterator: Iterator[(K, V)]
        def += (kv: (K, V)): This
        def -= (key: K): This

    If you wish that methods like `take`, `drop`, `filter` also return the same kind of map you should also override:

        def empty: This

    It is also good idea to override methods `foreach` and `size` for efficiency.

44.  trait MultiMap [A, B] extends Map[A, Set[B]]

    A trait for mutable maps with multiple values assigned to a key.

    A trait for mutable maps with multiple values assigned to a key.

    This class is typically used as a mixin. It turns maps which map `A` to `Set[B]` objects into multimaps that map `A` to `B` objects.

    Example:

    1.     // first import all necessary types from package `collection.mutable`
           import collection.mutable.{ HashMap, MultiMap, Set }

           // to create a `MultiMap` the easiest way is to mixin it into a normal
           // `Map` instance
           val mm = new HashMap[Int, Set[String]] with MultiMap[Int, String]

           // to add key-value pairs to a multimap it is important to use
           // the method `addBinding` because standard methods like `+` will
           // overwrite the complete key-value pair instead of adding the
           // value to the existing key
           mm.addBinding(1, "a")
           mm.addBinding(2, "b")
           mm.addBinding(1, "c")

           // mm now contains `Map(2 -> Set(b), 1 -> Set(c, a))`

           // to check if the multimap contains a value there is method
           // `entryExists`, which allows to traverse the including set
           mm.entryExists(1, _ == "a") == true
           mm.entryExists(1, _ == "b") == false
           mm.entryExists(2, _ == "b") == true

           // to remove a previous added value there is the method `removeBinding`
           mm.removeBinding(1, "a")
           mm.entryExists(1, _ == "a") == false

45.  class MutableList [A] extends AbstractSeq[A] with LinearSeq[A] with LinearSeqOptimized[A, MutableList[A]] with GenericTraversableTemplate[A, MutableList] with Builder[A, MutableList[A]] with Serializable

    This class is used internally to represent mutable lists.

    This class is used internally to represent mutable lists. It is the basis for the implementation of the class `Queue`.

    Annotations
      @SerialVersionUID()
    Version

      2.8

    Since

      1

46.  class OpenHashMap [Key, Value] extends AbstractMap[Key, Value] with Map[Key, Value] with MapLike[Key, Value, OpenHashMap[Key, Value]]

    A mutable hash map based on an open hashing scheme.

    A mutable hash map based on an open hashing scheme. The precise scheme is undefined, but it should make a reasonable effort to ensure that an insert with consecutive hash codes is not unnecessarily penalised. In particular, mappings of consecutive integer keys should work without significant performance loss.

    Key

      type of the keys in this map.

    Value

      type of the values in this map.

    Since

      2.7

47.  sealed class PriorityQueue [A] extends AbstractIterable[A] with Iterable[A] with GenericOrderedTraversableTemplate[A, PriorityQueue] with IterableLike[A, PriorityQueue[A]] with Growable[A] with Builder[A, PriorityQueue[A]] with Serializable with scala.Cloneable

    This class implements priority queues using a heap.

    This class implements priority queues using a heap. To prioritize elements of type A there must be an implicit Ordering[A] available at creation.

    Only the `dequeue` and `dequeueAll` methods will return elements in priority order (while removing elements from the heap). Standard collection methods including `drop`, `iterator`, and `toString` will remove or traverse the heap in whichever order seems most convenient.

    Therefore, printing a `PriorityQueue` will not reveal the priority order of the elements, though the highest-priority element will be printed first. To print the elements in order, one must duplicate the `PriorityQueue` (by using `clone`, for instance) and then dequeue them:

    A

      type of the elements in this priority queue.

    Example:

    1.     val pq = collection.mutable.PriorityQueue(1, 2, 5, 3, 7)
           println(pq)                  // elements probably not in order
           println(pq.clone.dequeueAll) // prints Vector(7, 5, 3, 2, 1)

    Version

      1.0, 03/05/2004

    Since

      1

48.  trait Publisher [Evt] extends AnyRef

    `Publisher[A,This]` objects publish events of type `A` to all registered subscribers.

    `Publisher[A,This]` objects publish events of type `A` to all registered subscribers. When subscribing, a subscriber may specify a filter which can be used to constrain the number of events sent to the subscriber. Subscribers may suspend their subscription, or reactivate a suspended subscription. Class `Publisher` is typically used as a mixin. The abstract type `Pub` models the type of the publisher itself.

    Evt

      type of the published event.

    Version

      2.8

    Since

      1

49.  class Queue [A] extends MutableList[A] with LinearSeqOptimized[A, Queue[A]] with GenericTraversableTemplate[A, Queue] with Cloneable[Queue[A]] with Serializable

    `Queue` objects implement data structures that allow to insert and retrieve elements in a first-in-first-out (FIFO) manner.

    `Queue` objects implement data structures that allow to insert and retrieve elements in a first-in-first-out (FIFO) manner.

    Version

      2.8

    Since

      1

    See also

      "Scala's Collection Library overview" section on `Queues` for more information.

50.  trait ResizableArray [A] extends IndexedSeq[A] with GenericTraversableTemplate[A, ResizableArray] with IndexedSeqOptimized[A, ResizableArray[A]]

    This class is used internally to implement data structures that are based on resizable arrays.

    This class is used internally to implement data structures that are based on resizable arrays.

    A

      type of the elements contained in this resizable array.

    Version

      2.8

    Since

      1

51.  trait ReusableBuilder [-Elem, +To] extends Builder[Elem, To]

    `ReusableBuilder` is a marker trait that indicates that a `Builder` can be reused to build more than one instance of a collection.

    `ReusableBuilder` is a marker trait that indicates that a `Builder` can be reused to build more than one instance of a collection. In particular, calling `result` followed by `clear` will produce a collection and reset the builder to begin building a new collection of the same type.

    It is up to subclasses to implement this behavior, and to document any other behavior that varies from standard `ReusableBuilder` usage (e.g. operations being well-defined after a call to `result`, or allowing multiple calls to result to obtain different snapshots of a collection under construction).

    Elem

      the type of elements that get added to the builder.

    To

      the type of collection that it produced.

    Since

      2.12

52.  class RevertibleHistory [Evt <: Undoable, Pub] extends History[Evt, Pub] with Undoable with Serializable

    A revertible history is a `History` object which supports an undo operation.

    A revertible history is a `History` object which supports an undo operation. Type variable `Evt` refers to the type of the published events, `Pub` denotes the publisher type. Type `Pub` is typically a subtype of `Publisher`.

    Evt

      type of the events

    Pub

      type of the publisher

    Version

      1.0, 08/07/2003

    Since

      2.8

53.  trait Seq [A] extends Iterable[A] with collection.Seq[A] with GenericTraversableTemplate[A, Seq] with SeqLike[A, Seq[A]]

    A subtrait of `collection.Seq` which represents sequences that can be mutated.

    A subtrait of `collection.Seq` which represents sequences that can be mutated.

    Sequences are special cases of iterable collections of class `Iterable`. Unlike iterables, sequences always have a defined order of elements. Sequences provide a method `apply` for indexing. Indices range from `0` up to the `length` of a sequence. Sequences support a number of methods to find occurrences of elements or subsequences, including `segmentLength`, `prefixLength`, `indexWhere`, `indexOf`, `lastIndexWhere`, `lastIndexOf`, `startsWith`, `endsWith`, `indexOfSlice`.

    Another way to see a sequence is as a `PartialFunction` from `Int` values to the element type of the sequence. The `isDefinedAt` method of a sequence returns `true` for the interval from `0` until `length`.

    Sequences can be accessed in reverse order of their elements, using methods `reverse` and `reverseIterator`.

    Sequences have two principal subtraits, `IndexedSeq` and `LinearSeq`, which give different guarantees for performance. An `IndexedSeq` provides fast random-access of elements and a fast `length` operation. A `LinearSeq` provides fast access only to the first element via `head`, but also has a fast `tail` operation.

    The class adds an `update` method to `collection.Seq`.

54.  trait SeqLike [A, +This <: SeqLike[A, This] with Seq[A]] extends collection.SeqLike[A, This] with Cloneable[This] with Parallelizable[A, ParSeq[A]]

    A template trait for mutable sequences of type `mutable.Seq[A]`.

    A template trait for mutable sequences of type `mutable.Seq[A]`.

    A

      the type of the elements of the set

    This

      the type of the set itself.

55.  trait Set [A] extends Iterable[A] with collection.Set[A] with GenericSetTemplate[A, Set] with SetLike[A, Set[A]]

    A generic trait for mutable sets.

    A generic trait for mutable sets.

    To implement a concrete mutable set, you need to provide implementations of the following methods:

        def contains(elem: A): Boolean
        def iterator: Iterator[A]
        def += (elem: A): this.type
        def -= (elem: A): this.type

    If you wish that methods like `take`, `drop`, `filter` return the same kind of set, you should also override:

        def empty: This

    It is also good idea to override methods `foreach` and `size` for efficiency.

    Since

      1.0

56.  class SetBuilder [A, Coll <: collection.Set[A] with collection.SetLike[A, Coll]] extends ReusableBuilder[A, Coll]

    The canonical builder for mutable Sets.

    The canonical builder for mutable Sets.

    A

      The type of the elements that will be contained in this set.

    Coll

      The type of the actual collection this set builds.

    Since

      2.8

57.  trait SetLike [A, +This <: SetLike[A, This] with Set[A]] extends collection.SetLike[A, This] with Scriptable[A] with Builder[A, This] with Growable[A] with Shrinkable[A] with Cloneable[Set[A]] with Parallelizable[A, ParSet[A]]

    A template trait for mutable sets of type `mutable.Set[A]`.

    A template trait for mutable sets of type `mutable.Set[A]`.

    This trait provides most of the operations of a `mutable.Set` independently of its representation. It is typically inherited by concrete implementations of sets.

    To implement a concrete mutable set, you need to provide implementations of the following methods:

        def contains(elem: A): Boolean
        def iterator: Iterator[A]
        def += (elem: A): this.type
        def -= (elem: A): this.type

    If you wish that methods like `take`, `drop`, `filter` return the same kind of set, you should also override:

        def empty: This

    It is also good idea to override methods `foreach` and `size` for efficiency.

    A

      the type of the elements of the set

    This

      the type of the set itself.

    Version

      2.8

    Since

      2.8

58.  trait SortedMap [A, B] extends Map[A, B] with collection.SortedMap[A, B] with MapLike[A, B, SortedMap[A, B]] with SortedMapLike[A, B, SortedMap[A, B]]

    A mutable map whose keys are sorted.

    A mutable map whose keys are sorted.

    A

      the type of the keys contained in this sorted map.

    B

      the type of the values associated with the keys.

    Version

      2.12

    Since

      2.12

59.  trait SortedSet [A] extends collection.SortedSet[A] with SortedSetLike[A, SortedSet[A]] with Set[A] with SetLike[A, SortedSet[A]]

    Base trait for mutable sorted set.

60.  final class StringBuilder extends AbstractSeq[Char] with CharSequence with IndexedSeq[Char] with StringLike[StringBuilder] with ReusableBuilder[Char, String] with Serializable

    A builder for mutable sequence of characters.

    A builder for mutable sequence of characters. This class provides an API mostly compatible with `java.lang.StringBuilder`, except where there are conflicts with the Scala collections API (such as the `reverse` method.)

    Annotations
      @SerialVersionUID()
    Version

      2.8

    Since

      2.7

61.  trait Subscriber [-Evt, -Pub] extends AnyRef

    `Subscriber[A, B]` objects may subscribe to events of type `A` published by an object of type `B`.

    `Subscriber[A, B]` objects may subscribe to events of type `A` published by an object of type `B`. `B` is typically a subtype of scala.collection.mutable.Publisher.

    Version

      2.8

    Since

      1

62.  trait Traversable [A] extends collection.Traversable[A] with GenericTraversableTemplate[A, Traversable] with TraversableLike[A, Traversable[A]] with Mutable

    A trait for traversable collections that can be mutated.

    A trait for traversable collections that can be mutated.

    This is a base trait of all kinds of mutable Scala collections. It implements the behavior common to all collections, in terms of a method `foreach` with signature:

        def foreach[U](f: Elem => U): Unit

    Collection classes mixing in this trait provide a concrete `foreach` method which traverses all the elements contained in the collection, applying a given function to each. They also need to provide a method `newBuilder` which creates a builder for collections of the same kind.

    A traversable class might or might not have two properties: strictness and orderedness. Neither is represented as a type.

    The instances of a strict collection class have all their elements computed before they can be used as values. By contrast, instances of a non-strict collection class may defer computation of some of their elements until after the instance is available as a value. A typical example of a non-strict collection class is a scala.collection.immutable.Stream. A more general class of examples are `TraversableViews`.

    If a collection is an instance of an ordered collection class, traversing its elements with `foreach` will always visit elements in the same order, even for different runs of the program. If the class is not ordered, `foreach` can visit elements in different orders for different runs (but it will keep the same order in the same run).'

    A typical example of a collection class which is not ordered is a `HashMap` of objects. The traversal order for hash maps will depend on the hash codes of its elements, and these hash codes might differ from one run to the next. By contrast, a `LinkedHashMap` is ordered because its `foreach` method visits elements in the order they were inserted into the `HashMap`.

63.  sealed class TreeMap [A, B] extends AbstractSortedMap[A, B] with SortedMap[A, B] with MapLike[A, B, TreeMap[A, B]] with SortedMapLike[A, B, TreeMap[A, B]] with Serializable

    A mutable sorted map implemented using a mutable red-black tree as underlying data structure.

    A mutable sorted map implemented using a mutable red-black tree as underlying data structure.

    A

      the type of the keys contained in this tree map.

    B

      the type of the values associated with the keys.

    Annotations
      @SerialVersionUID()
    Version

      2.12

    Since

      2.12

64.  sealed class TreeSet [A] extends AbstractSortedSet[A] with SortedSet[A] with SetLike[A, TreeSet[A]] with SortedSetLike[A, TreeSet[A]] with Serializable

    A mutable sorted set implemented using a mutable red-black tree as underlying data structure.

    A mutable sorted set implemented using a mutable red-black tree as underlying data structure.

    A

      the type of the keys contained in this tree set.

    Annotations
      @SerialVersionUID()
    Version

      2.12

    Since

      2.10

65.  trait Undoable extends AnyRef

    Classes that mix in the `Undoable` class provide an operation `undo` which can be used to undo the last operation.

    Classes that mix in the `Undoable` class provide an operation `undo` which can be used to undo the last operation.

    Version

      1.0, 08/07/2003

    Since

      1

66.  sealed class UnrolledBuffer [T] extends AbstractBuffer[T] with Buffer[T] with BufferLike[T, UnrolledBuffer[T]] with GenericClassTagTraversableTemplate[T, UnrolledBuffer] with Builder[T, UnrolledBuffer[T]] with Serializable

    A buffer that stores elements in an unrolled linked list.

    A buffer that stores elements in an unrolled linked list.

    Unrolled linked lists store elements in linked fixed size arrays.

    Unrolled buffers retain locality and low memory overhead properties of array buffers, but offer much more efficient element addition, since they never reallocate and copy the internal array.

    However, they provide `O(n/m)` complexity random access, where `n` is the number of elements, and `m` the size of internal array chunks.

    Ideal to use when:

    - elements are added to the buffer and then all of the elements are traversed sequentially
    - two unrolled buffers need to be concatenated (see `concat`)

    Better than singly linked lists for random access, but should still be avoided for such a purpose.

    Annotations
      @SerialVersionUID()
67.  class WeakHashMap [A, B] extends convert.Wrappers.JMapWrapper[A, B] with convert.Wrappers.JMapWrapperLike[A, B, WeakHashMap[A, B]]

    A hash map with references to entries which are weakly reachable.

    A hash map with references to entries which are weakly reachable. Entries are removed from this map when the key is no longer (strongly) referenced. This class wraps `java.util.WeakHashMap`.

    A

      type of keys contained in this map

    B

      type of values associated with the keys

    Since

      2.8

    See also

      "Scala's Collection Library overview" section on `Weak Hash Maps` for more information.

68.  abstract class WrappedArray [T] extends AbstractSeq[T] with IndexedSeq[T] with ArrayLike[T, WrappedArray[T]] with CustomParallelizable[T, ParArray[T]]

    A class representing `Array[T]`.

    A class representing `Array[T]`.

    T

      type of the elements in this wrapped array.

    Version

      1.0

    Since

      2.8

69.  class WrappedArrayBuilder [A] extends ReusableBuilder[A, WrappedArray[A]]

    A builder class for arrays.

    A builder class for arrays.

    This builder can be reused.

    A

      type of elements that can be added to this builder.

    Since

      2.8

70.  trait BufferProxy [A] extends Buffer[A] with Proxy

    This is a simple proxy class for `scala.collection.mutable.Buffer`.

    This is a simple proxy class for `scala.collection.mutable.Buffer`. It is most useful for assembling customized set abstractions dynamically using object composition and forwarding.

    A

      type of the elements the buffer proxy contains.

    Annotations
      @deprecated
    Deprecated

      (Since version 2.11.0) proxying is deprecated due to lack of use and compiler-level support

    Version

      1.0, 16/04/2004

    Since

      1

71.  trait DefaultMapModel [A, B] extends Map[A, B]

    This class is used internally.

    This class is used internally. It implements the mutable `Map` class in terms of three functions: `findEntry`, `addEntry`, and `entries`.

    Annotations
      @deprecated
    Deprecated

      (Since version 2.11.0) this trait will be removed

    Version

      1.0, 08/07/2003

    Since

      1

72.  class DoubleLinkedList [A] extends AbstractSeq[A] with LinearSeq[A] with GenericTraversableTemplate[A, DoubleLinkedList] with DoubleLinkedListLike[A, DoubleLinkedList[A]] with Serializable

    This class implements double linked lists where both the head (`elem`), the tail (`next`) and a reference to the previous node (`prev`) are mutable.

    This class implements double linked lists where both the head (`elem`), the tail (`next`) and a reference to the previous node (`prev`) are mutable.

    A

      the type of the elements contained in this double linked list.

    Annotations
      @deprecated @SerialVersionUID()
    Deprecated

      (Since version 2.11.0) low-level linked lists are deprecated due to idiosyncrasies in interface and incomplete features

    Version

      2.8

    Since

      1

    See also

      "Scala's Collection Library overview" section on `Double Linked Lists` for more information.

73.  trait DoubleLinkedListLike [A, This <: Seq[A] with DoubleLinkedListLike[A, This]] extends SeqLike[A, This] with LinkedListLike[A, This]

    This extensible class may be used as a basis for implementing double linked lists.

    This extensible class may be used as a basis for implementing double linked lists. Type variable `A` refers to the element type of the list, type variable `This` is used to model self types of linked lists.

    The invariant of this data structure is that `prev` is always a reference to the previous node in the list. If `this` is the first node of the list, `prev` will be `null`. Field `next` is set to `this` iff the list is empty.

    Examples (right arrow represents `next`, left arrow represents `prev`, `_` represents no value):

        Empty:

        null <-- [ _ ] --,
                 [   ] <-`

        Single element:

        null <-- [ x ] --> [ _ ] --,
                 [   ] <-- [   ] <-`

        More elements:

        null <-- [ x ] --> [ y ] --> [ z ] --> [ _ ] --,
                 [   ] <-- [   ] <-- [   ] <-- [   ] <-`

    A

      type of the elements contained in the double linked list

    This

      the type of the actual linked list holding the elements

    Annotations
      @deprecated
    Deprecated

      (Since version 2.11.0) low-level linked lists are deprecated due to idiosyncrasies in interface and incomplete features

    Version

      1.0, 08/07/2003

    Since

      2.8

74.  class ImmutableMapAdaptor [A, B] extends AbstractMap[A, B] with Map[A, B] with Serializable

    This class can be used as an adaptor to create mutable maps from immutable map implementations.

    This class can be used as an adaptor to create mutable maps from immutable map implementations. Only method `empty` has to be redefined if the immutable map on which this mutable map is originally based is not empty. `empty` is supposed to return the representation of an empty map.

    Annotations
      @deprecated
    Deprecated

      (Since version 2.11.0) adaptors are inherently unreliable and prone to performance problems

    Version

      2.0, 01/01/2007

    Since

      1

75.  class ImmutableSetAdaptor [A] extends AbstractSet[A] with Set[A] with Serializable

    This class can be used as an adaptor to create mutable sets from immutable set implementations.

    This class can be used as an adaptor to create mutable sets from immutable set implementations. Only method `empty` has to be redefined if the immutable set on which this mutable set is originally based is not empty. `empty` is supposed to return the representation of an empty set.

    Annotations
      @deprecated
    Deprecated

      (Since version 2.11.0) adaptors are inherently unreliable and prone to performance problems

    Version

      1.0, 21/07/2003

    Since

      1

76.  class LinkedList [A] extends AbstractSeq[A] with LinearSeq[A] with GenericTraversableTemplate[A, LinkedList] with LinkedListLike[A, LinkedList[A]] with Serializable

    A more traditional/primitive style of linked list where the "list" is also the "head" link.

    A more traditional/primitive style of linked list where the "list" is also the "head" link. Links can be manually created and manipulated, though the use of the API, when possible, is recommended.

    The danger of directly manipulating next:

        scala> val b = LinkedList(1)
        b: scala.collection.mutable.LinkedList[Int] = LinkedList(1)

        scala> b.next = null

        scala> println(b)
        java.lang.NullPointerException

    If the list is empty `next` must be set to `this`. The last node in every mutable linked list is empty.

    Examples (`_` represents no value):

        Empty:

        [ _ ] --,
        [   ] <-`

        Single element:

        [ x ] --> [ _ ] --,
                  [   ] <-`

        More elements:

        [ x ] --> [ y ] --> [ z ] --> [ _ ] --,
                                      [   ] <-`

    A

      the type of the elements contained in this linked list.

    Annotations
      @SerialVersionUID() @deprecated
    Deprecated

      (Since version 2.11.0) low-level linked lists are deprecated due to idiosyncrasies in interface and incomplete features

    Version

      2.8

    Since

      1

    See also

      "Scala's Collection Library overview" section on `Linked Lists` for more information.

77.  trait LinkedListLike [A, This <: Seq[A] with LinkedListLike[A, This]] extends SeqLike[A, This]

    This extensible class may be used as a basis for implementing linked list.

    This extensible class may be used as a basis for implementing linked list. Type variable `A` refers to the element type of the list, type variable `This` is used to model self types of linked lists.

    If the list is empty `next` must be set to `this`. The last node in every mutable linked list is empty.

    Examples (`_` represents no value):

        Empty:

        [ _ ] --,
        [   ] <-`

        Single element:

        [ x ] --> [ _ ] --,
                  [   ] <-`

        More elements:

        [ x ] --> [ y ] --> [ z ] --> [ _ ] --,
                                      [   ] <-`

    A

      type of the elements contained in the linked list

    This

      the type of the actual linked list holding the elements

    Annotations
      @deprecated
    Deprecated

      (Since version 2.11.0) low-level linked lists are deprecated due to idiosyncrasies in interface and incomplete features

    Version

      1.0, 08/07/2003

    Since

      2.8

78.  trait MapProxy [A, B] extends Map[A, B] with MapProxyLike[A, B, Map[A, B]]

    This trait implements a proxy for scala.collection.mutable.Map.

    This trait implements a proxy for scala.collection.mutable.Map.

    It is most useful for assembling customized map abstractions dynamically using object composition and forwarding.

    Annotations
      @deprecated
    Deprecated

      (Since version 2.11.0) proxying is deprecated due to lack of use and compiler-level support

    Version

      2.0, 31/12/2006

    Since

      1

79.  trait ObservableBuffer [A] extends Buffer[A] with Publisher[Message[A] with Undoable]

    This class is typically used as a mixin.

    This class is typically used as a mixin. It adds a subscription mechanism to the `Buffer` class into which this abstract class is mixed in. Class `ObservableBuffer` publishes events of the type `Message`.

    Annotations
      @deprecated
    Deprecated

      (Since version 2.11.0) observables are deprecated because scripting is deprecated

    Version

      1.0, 08/07/2003

    Since

      1

80.  trait ObservableMap [A, B] extends Map[A, B] with Publisher[Message[(A, B)] with Undoable]

    This class is typically used as a mixin.

    This class is typically used as a mixin. It adds a subscription mechanism to the `Map` class into which this abstract class is mixed in. Class `ObservableMap` publishes events of the type `Message`.

    Annotations
      @deprecated
    Deprecated

      (Since version 2.11.0) observables are deprecated because scripting is deprecated

    Version

      2.0, 31/12/2006

    Since

      1

81.  trait ObservableSet [A] extends Set[A] with Publisher[Message[A] with Undoable]

    This class is typically used as a mixin.

    This class is typically used as a mixin. It adds a subscription mechanism to the `Set` class into which this abstract class is mixed in. Class `ObservableSet` publishes events of the type `Message`.

    Annotations
      @deprecated
    Deprecated

      (Since version 2.11.0) observables are deprecated because scripting is deprecated

    Version

      1.0, 08/07/2003

    Since

      1

82.  sealed abstract class PriorityQueueProxy [A] extends PriorityQueue[A] with Proxy

    This class servers as a proxy for priority queues.

    This class servers as a proxy for priority queues. The elements of the queue have to be ordered in terms of the `Ordered[T]` class.

    Annotations
      @deprecated
    Deprecated

      (Since version 2.11.0) proxying is deprecated due to lack of use and compiler-level support

    Version

      1.0, 03/05/2004

    Since

      1

83.  trait QueueProxy [A] extends Queue[A] with Proxy

    `Queue` objects implement data structures that allow to insert and retrieve elements in a first-in-first-out (FIFO) manner.

    `Queue` objects implement data structures that allow to insert and retrieve elements in a first-in-first-out (FIFO) manner.

    A

      type of the elements in this queue proxy.

    Annotations
      @deprecated
    Deprecated

      (Since version 2.11.0) proxying is deprecated due to lack of use and compiler-level support

    Version

      1.1, 03/05/2004

    Since

      1

84.  trait SetProxy [A] extends Set[A] with SetProxyLike[A, Set[A]]

    This is a simple wrapper class for scala.collection.mutable.Set.

    This is a simple wrapper class for scala.collection.mutable.Set. It is most useful for assembling customized set abstractions dynamically using object composition and forwarding.

    Annotations
      @deprecated
    Deprecated

      (Since version 2.11.0) proxying is deprecated due to lack of use and compiler-level support

    Version

      1.1, 09/05/2004

    Since

      1

85.  class Stack [A] extends AbstractSeq[A] with Seq[A] with SeqLike[A, Stack[A]] with GenericTraversableTemplate[A, Stack] with Cloneable[Stack[A]] with Serializable

    A stack implements a data structure which allows to store and retrieve objects in a last-in-first-out (LIFO) fashion.

    A stack implements a data structure which allows to store and retrieve objects in a last-in-first-out (LIFO) fashion.

    A

      type of the elements contained in this stack.

    Annotations
      @deprecated
    Deprecated

      (Since version 2.12.0) Stack is an inelegant and potentially poorly-performing wrapper around List. Use a List assigned to a var instead.

    Version

      2.8

    Since

      1

    See also

      "Scala's Collection Library overview" section on `Stacks` for more information.

86.  trait StackProxy [A] extends Stack[A] with Proxy

    A stack implements a data structure which allows to store and retrieve objects in a last-in-first-out (LIFO) fashion.

    A stack implements a data structure which allows to store and retrieve objects in a last-in-first-out (LIFO) fashion.

    A

      type of the elements in this stack proxy.

    Annotations
      @deprecated
    Deprecated

      (Since version 2.11.0) proxying is deprecated due to lack of use and compiler-level support

    Version

      1.0, 10/05/2004

    Since

      1

87.  trait SynchronizedBuffer [A] extends Buffer[A]

    This class should be used as a mixin.

    This class should be used as a mixin. It synchronizes the `Buffer` methods of the class into which it is mixed in.

    A

      type of the elements contained in this buffer.

    Annotations
      @deprecated
    Deprecated

      (Since version 2.11.0) Synchronization via traits is deprecated as it is inherently unreliable. Consider java.util.concurrent.ConcurrentLinkedQueue as an alternative.

    Version

      1.0, 08/07/2003

    Since

      1

88.  trait SynchronizedMap [A, B] extends Map[A, B]

    This class should be used as a mixin.

    This class should be used as a mixin. It synchronizes the `Map` functions of the class into which it is mixed in.

    A

      type of the keys contained in this map.

    B

      type of the values associated with keys.

    Annotations
      @deprecated
    Deprecated

      (Since version 2.11.0) Synchronization via traits is deprecated as it is inherently unreliable. Consider java.util.concurrent.ConcurrentHashMap as an alternative.

    Version

      2.0, 31/12/2006

    Since

      1

89.  sealed class SynchronizedPriorityQueue [A] extends PriorityQueue[A]

    This class implements synchronized priority queues using a binary heap.

    This class implements synchronized priority queues using a binary heap. The elements of the queue have to be ordered in terms of the `Ordered[T]` class.

    A

      type of the elements contained in this synchronized priority queue

    Annotations
      @deprecated
    Deprecated

      (Since version 2.11.0) Comprehensive synchronization via selective overriding of methods is inherently unreliable. Consider java.util.concurrent.ConcurrentSkipListSet as an alternative.

    Version

      1.0, 03/05/2004

    Since

      1

90.  class SynchronizedQueue [A] extends Queue[A]

    This is a synchronized version of the `Queue[T]` class.

    This is a synchronized version of the `Queue[T]` class. It implements a data structure that allows one to insert and retrieve elements in a first-in-first-out (FIFO) manner.

    A

      type of elements contained in this synchronized queue.

    Annotations
      @deprecated
    Deprecated

      (Since version 2.11.0) Synchronization via selective overriding of methods is inherently unreliable. Consider java.util.concurrent.ConcurrentLinkedQueue as an alternative.

    Version

      1.0, 03/05/2004

    Since

      1

91.  trait SynchronizedSet [A] extends Set[A]

    This class should be used as a mixin.

    This class should be used as a mixin. It synchronizes the `Set` functions of the class into which it is mixed in.

    A

      type of the elements contained in this synchronized set.

    Annotations
      @deprecated
    Deprecated

      (Since version 2.11.0) Synchronization via traits is deprecated as it is inherently unreliable. Consider java.util.concurrent.ConcurrentHashMap[A,Unit] as an alternative.

    Version

      1.0, 08/07/2003

    Since

      1

92.  class SynchronizedStack [A] extends Stack[A]

    This is a synchronized version of the `Stack[T]` class.

    This is a synchronized version of the `Stack[T]` class. It implements a data structure which allows to store and retrieve objects in a last-in-first-out (LIFO) fashion.

    A

      type of the elements contained in this stack.

    Annotations
      @deprecated
    Deprecated

      (Since version 2.11.0) Synchronization via selective overriding of methods is inherently unreliable. Consider java.util.concurrent.LinkedBlockingDequeue instead.

    Version

      1.0, 03/05/2004

    Since

      1

### Value Members

1.  object AnyRefMap extends Serializable
2.  object ArrayBuffer extends SeqFactory[ArrayBuffer] with Serializable

   Factory object for the `ArrayBuffer` class.

   Factory object for the `ArrayBuffer` class.

   This object provides a set of operations to create ``ArrayBuffer`` values.

3.  object ArrayBuilder extends Serializable

   A companion object for array builders.

   A companion object for array builders.

   Since

     2.8

4.  object ArrayOps

   A companion object for `ArrayOps`.

   A companion object for `ArrayOps`.

   Since

     2.8

5.  object ArraySeq extends SeqFactory[ArraySeq] with Serializable

   This object provides a set of operations to create ``ArraySeq`` values.

6.  object ArrayStack extends SeqFactory[ArrayStack] with Serializable

   Factory object for the `ArrayStack` class.

   Factory object for the `ArrayStack` class.

   This object provides a set of operations to create ``ArrayStack`` values.

7.  object BitSet extends BitSetFactory[BitSet] with Serializable

   This object provides a set of operations to create ``BitSet`` values.

8.  object Buffer extends SeqFactory[Buffer]

   This object provides a set of operations to create ``Buffer`` values.

9.  object HashMap extends MutableMapFactory[HashMap] with Serializable

   This object provides a set of operations needed to create ``mutable.HashMap`` values.

10.  object HashSet extends MutableSetFactory[HashSet] with Serializable

    This object provides a set of operations needed to create ``mutable.HashSet`` values.

11.  object IndexedSeq extends SeqFactory[IndexedSeq]

    This object provides a set of operations to create ``mutable.IndexedSeq`` values.

    This object provides a set of operations to create ``mutable.IndexedSeq`` values. The current default implementation of a `mutable.IndexedSeq` is an `ArrayBuffer`.

12.  object IndexedSeqView

    An object containing the necessary implicit definitions to make `SeqView`s work.

    An object containing the necessary implicit definitions to make `SeqView`s work. Its definitions are generally not accessed directly by clients.

    Note that the `canBuildFrom` factories yield `SeqView`s, not `IndexedSeqView`s. This is intentional, because not all operations yield again a `mutable.IndexedSeqView`. For instance, `map` just gives a `SeqView`, which reflects the fact that `map` cannot do its work and maintain a pointer into the original indexed sequence.

13.  object Iterable extends GenTraversableFactory[Iterable] with TraversableFactory[Iterable]

    This object provides a set of operations to create ``mutable.Iterable`` values.

    This object provides a set of operations to create ``mutable.Iterable`` values. The current default implementation of a `mutable.Iterable` is an `ArrayBuffer`.

14.  object LinearSeq extends SeqFactory[LinearSeq]

    This object provides a set of operations to create ``mutable.LinearSeq`` values.

    This object provides a set of operations to create ``mutable.LinearSeq`` values. The current default implementation of a `mutable.LinearSeq` is a `MutableList`.

15.  object LinkedHashMap extends MutableMapFactory[LinkedHashMap] with Serializable

    This object provides a set of operations needed to create ``LinkedHashMap`` values.

16.  object LinkedHashSet extends MutableSetFactory[LinkedHashSet] with Serializable

    This object provides a set of operations needed to create ``LinkedHashSet`` values.

17.  object ListBuffer extends SeqFactory[ListBuffer] with Serializable

    This object provides a set of operations to create ``ListBuffer`` values.

18.  object ListMap extends MutableMapFactory[ListMap] with Serializable

    This object provides a set of operations needed to create ``mutable.ListMap`` values.

19.  object LongMap extends Serializable
20.  object Map extends MutableMapFactory[Map]

    This object provides a set of operations needed to create ``mutable.Map`` values.

    This object provides a set of operations needed to create ``mutable.Map`` values. The current default implementation of a `mutable.Map` is a `HashMap`.

21.  object MutableList extends SeqFactory[MutableList] with Serializable
22.  object OpenHashMap

23.  object PriorityQueue extends OrderedTraversableFactory[PriorityQueue] with Serializable
24.  object Queue extends SeqFactory[Queue] with Serializable
25.  object ResizableArray extends SeqFactory[ResizableArray]
26.  object Seq extends SeqFactory[Seq]

    This object provides a set of operations to create ``mutable.Seq`` values.

    This object provides a set of operations to create ``mutable.Seq`` values. The current default implementation of a `mutable.Seq` is an `ArrayBuffer`.

27.  object Set extends MutableSetFactory[Set]

    This object provides a set of operations needed to create ``mutable.Set`` values.

    This object provides a set of operations needed to create ``mutable.Set`` values. The current default implementation of a `mutable.Set` is a `HashSet`.

28.  object SortedMap extends MutableSortedMapFactory[SortedMap]

    This object provides a set of operations needed to create sorted maps of type `mutable.SortedMap`.

29.  object SortedSet extends MutableSortedSetFactory[SortedSet]

    A template for mutable sorted set companion objects.

30.  object Stack extends SeqFactory[Stack] with Serializable

    Factory object for the `mutable.Stack` class.

    Factory object for the `mutable.Stack` class.

    This object provides a set of operations to create ``mutable.Stack`` values.

31.  object StringBuilder extends Serializable
32.  object Traversable extends GenTraversableFactory[Traversable] with TraversableFactory[Traversable]

    This object provides a set of operations to create ``mutable.Traversable`` values.

    This object provides a set of operations to create ``mutable.Traversable`` values. The current default implementation of a `mutable.Traversable` is an `ArrayBuffer`.

33.  object TreeMap extends MutableSortedMapFactory[TreeMap] with Serializable

    This object provides a set of operations needed to create sorted maps of type `mutable.TreeMap`.

34.  object TreeSet extends MutableSortedSetFactory[TreeSet] with Serializable

35.  object UnrolledBuffer extends ClassTagTraversableFactory[UnrolledBuffer] with Serializable
36.  object WeakHashMap extends MutableMapFactory[WeakHashMap] with Serializable

    This object provides a set of operations needed to create ``WeakHashMap`` values.

37.  object WrappedArray

    A companion object used to create instances of `WrappedArray`.

### Deprecated Value Members

1.  object DoubleLinkedList extends SeqFactory[DoubleLinkedList] with Serializable

   This object provides a set of operations to create ``DoubleLinkedList`` values.

   This object provides a set of operations to create ``DoubleLinkedList`` values.

   Annotations
     @deprecated
   Deprecated

     (Since version 2.11.0) low-level linked lists are deprecated

2.  object LinkedList extends SeqFactory[LinkedList] with Serializable

   This object provides a set of operations to create ``LinkedList`` values.

   This object provides a set of operations to create ``LinkedList`` values.

   Annotations
     @deprecated
   Deprecated

     (Since version 2.11.0) low-level linked lists are deprecated

### Ungrouped