Scala Standard Library2.12.17 < Back
 

# 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
-  package parallel

  Package object for parallel collections.

  Package object for parallel collections.

  Definition Classes
    collection
-  package script
  Definition Classes
    collection
- +:
- :+
- AbstractIterable
- AbstractIterator
- AbstractMap
- AbstractSeq
- AbstractSet
- AbstractTraversable
- BitSet
- BitSetLike
- BufferedIterator
- CustomParallelizable
- DefaultMap
- GenIterable
- GenIterableLike
- GenMap
- GenMapLike
- GenSeq
- GenSeqLike
- GenSet
- GenSetLike
- GenTraversable
- GenTraversableLike
- GenTraversableOnce
- IndexedSeq
- IndexedSeqLike
- IndexedSeqOptimized
- Iterable
- IterableLike
- IterableProxy
- IterableProxyLike
- IterableView
- IterableViewLike
- Iterator
- JavaConversions
- JavaConverters
- LinearSeq
- LinearSeqLike
- LinearSeqOptimized
- Map
- MapLike
- MapProxy
- MapProxyLike
- Parallel
- Parallelizable
- Searching
- Seq
- SeqLike
- SeqProxy
- SeqProxyLike
- SeqView
- SeqViewLike
- Set
- SetLike
- SetProxy
- SetProxyLike
- SortedMap
- SortedMapLike
- SortedSet
- SortedSetLike
- Traversable
- TraversableLike
- TraversableOnce
- TraversableProxy
- TraversableProxyLike
- TraversableView
- TraversableViewLike
- ViewMkString

o

scala.collection

# GenIterable 

###
Companion trait GenIterable

#### object GenIterable extends GenTraversableFactory[GenIterable]

Source
  GenIterable.scala

Linear Supertypes
GenTraversableFactory[GenIterable], GenericCompanion[GenIterable], AnyRef, Any
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Ordering

1. Alphabetic
2. By Inheritance

Inherited

1. GenIterable
2. GenTraversableFactory
3. GenericCompanion
4. AnyRef
5. Any

1. Hide All
2. Show All

Visibility

1. Public
2. All

### Type Members

1.  type Coll = GenIterable[_]

   The underlying collection type with unknown element type

   The underlying collection type with unknown element type

   Attributes
     protected[this]
   Definition Classes
     GenericCompanion
2.  class GenericCanBuildFrom[A] extends CanBuildFrom[CC[_], A, CC[A]]

   A generic implementation of the `CanBuildFrom` trait, which forwards all calls to `apply(from)` to the `genericBuilder` method of collection `from`, and which forwards all calls of `apply()` to the `newBuilder` method of this factory.

   A generic implementation of the `CanBuildFrom` trait, which forwards all calls to `apply(from)` to the `genericBuilder` method of collection `from`, and which forwards all calls of `apply()` to the `newBuilder` method of this factory.

   Definition Classes
     GenTraversableFactory

### Value Members

1.  final def !=(arg0: Any): Boolean

   Test two objects for inequality.

   Test two objects for inequality.

   returns

     `true` if !(this == that), false otherwise.

   Definition Classes
     AnyRef → Any
2.  final def ##(): Int

   Equivalent to `x.hashCode` except for boxed numeric types and `null`.

   Equivalent to `x.hashCode` except for boxed numeric types and `null`. For numerics, it returns a hash value which is consistent with value equality: if two value type instances compare as true, then ## will produce the same hash value for each of them. For `null` returns a hashcode where `null.hashCode` throws a `NullPointerException`.

   returns

     a hash value consistent with ==

   Definition Classes
     AnyRef → Any
3.  final def ==(arg0: Any): Boolean

   The expression `x == that` is equivalent to `if (x eq null) that eq null else x.equals(that)`.

   The expression `x == that` is equivalent to `if (x eq null) that eq null else x.equals(that)`.

   returns

     `true` if the receiver object is equivalent to the argument; `false` otherwise.

   Definition Classes
     AnyRef → Any
4.  def ReusableCBF: GenericCanBuildFrom[Nothing]
   Definition Classes
     GenTraversableFactory
5.  def apply[A](elems: A*): GenIterable[A]

   Creates a collection with the specified elements.

   Creates a collection with the specified elements.

   A

     the type of the collection's elements

   elems

     the elements of the created collection

   returns

     a new collection with elements `elems`

   Definition Classes
     GenericCompanion
6.  final def asInstanceOf[T0]: T0

   Cast the receiver object to be of type `T0`.

   Cast the receiver object to be of type `T0`.

   Note that the success of a cast at runtime is modulo Scala's erasure semantics. Therefore the expression `1.asInstanceOf[String]` will throw a `ClassCastException` at runtime, while the expression `List(1).asInstanceOf[List[String]]` will not. In the latter example, because the type argument is erased as part of compilation it is not possible to check whether the contents of the list are of the requested type.

   returns

     the receiver object.

   Definition Classes
     Any
   Exceptions thrown

     `ClassCastException` if the receiver object is not an instance of the erasure of type `T0`.

7.  implicit def canBuildFrom[A]: GenericCanBuildFrom[A]
8.  def clone(): AnyRef

   Create a copy of the receiver object.

   Create a copy of the receiver object.

   The default implementation of the `clone` method is platform dependent.

   returns

     a copy of the receiver object.

   Attributes
     protected[lang]
   Definition Classes
     AnyRef
   Annotations
     @throws( ... ) @native()
   Note

     not specified by SLS as a member of AnyRef

9.  def concat[A](xss: Traversable[A]*): GenIterable[A]

   Concatenates all argument collections into a single collection.

   Concatenates all argument collections into a single collection.

   xss

     the collections that are to be concatenated.

   returns

     the concatenation of all the collections.

   Definition Classes
     GenTraversableFactory
10.  def empty[A]: GenIterable[A]

    An empty collection of type ``CC`[A]`

    An empty collection of type ``CC`[A]`

    A

      the type of the collection's elements

    Definition Classes
      GenericCompanion
11.  final def eq(arg0: AnyRef): Boolean

    Tests whether the argument (`that`) is a reference to the receiver object (`this`).

    Tests whether the argument (`that`) is a reference to the receiver object (`this`).

    The `eq` method implements an equivalence relation on non-null instances of `AnyRef`, and has three additional properties:

    - It is consistent: for any non-null instances `x` and `y` of type `AnyRef`, multiple invocations of `x.eq(y)` consistently returns `true` or consistently returns `false`.
    - For any non-null instance `x` of type `AnyRef`, `x.eq(null)` and `null.eq(x)` returns `false`.
    - `null.eq(null)` returns `true`.

    When overriding the `equals` or `hashCode` methods, it is important to ensure that their behavior is consistent with reference equality. Therefore, if two objects are references to each other (`o1 eq o2`), they should be equal to each other (`o1 == o2`) and they should hash to the same value (`o1.hashCode == o2.hashCode`).

    returns

      `true` if the argument is a reference to the receiver object; `false` otherwise.

    Definition Classes
      AnyRef
12.  def equals(arg0: Any): Boolean

    The equality method for reference types.

    The equality method for reference types. Default implementation delegates to `eq`.

    See also `equals` in scala.Any.

    returns

      `true` if the receiver object is equivalent to the argument; `false` otherwise.

    Definition Classes
      AnyRef → Any
13.  def fill[A](n1: Int, n2: Int, n3: Int, n4: Int, n5: Int)(elem: ⇒ A): GenIterable[GenIterable[GenIterable[GenIterable[GenIterable[A]]]]]

    Produces a five-dimensional collection containing the results of some element computation a number of times.

    Produces a five-dimensional collection containing the results of some element computation a number of times.

    n1

      the number of elements in the 1st dimension

    n2

      the number of elements in the 2nd dimension

    n3

      the number of elements in the 3nd dimension

    n4

      the number of elements in the 4th dimension

    n5

      the number of elements in the 5th dimension

    elem

      the element computation

    returns

      A collection that contains the results of `n1 x n2 x n3 x n4 x n5` evaluations of `elem`.

    Definition Classes
      GenTraversableFactory
14.  def fill[A](n1: Int, n2: Int, n3: Int, n4: Int)(elem: ⇒ A): GenIterable[GenIterable[GenIterable[GenIterable[A]]]]

    Produces a four-dimensional collection containing the results of some element computation a number of times.

    Produces a four-dimensional collection containing the results of some element computation a number of times.

    n1

      the number of elements in the 1st dimension

    n2

      the number of elements in the 2nd dimension

    n3

      the number of elements in the 3nd dimension

    n4

      the number of elements in the 4th dimension

    elem

      the element computation

    returns

      A collection that contains the results of `n1 x n2 x n3 x n4` evaluations of `elem`.

    Definition Classes
      GenTraversableFactory
15.  def fill[A](n1: Int, n2: Int, n3: Int)(elem: ⇒ A): GenIterable[GenIterable[GenIterable[A]]]

    Produces a three-dimensional collection containing the results of some element computation a number of times.

    Produces a three-dimensional collection containing the results of some element computation a number of times.

    n1

      the number of elements in the 1st dimension

    n2

      the number of elements in the 2nd dimension

    n3

      the number of elements in the 3nd dimension

    elem

      the element computation

    returns

      A collection that contains the results of `n1 x n2 x n3` evaluations of `elem`.

    Definition Classes
      GenTraversableFactory
16.  def fill[A](n1: Int, n2: Int)(elem: ⇒ A): GenIterable[GenIterable[A]]

    Produces a two-dimensional collection containing the results of some element computation a number of times.

    Produces a two-dimensional collection containing the results of some element computation a number of times.

    n1

      the number of elements in the 1st dimension

    n2

      the number of elements in the 2nd dimension

    elem

      the element computation

    returns

      A collection that contains the results of `n1 x n2` evaluations of `elem`.

    Definition Classes
      GenTraversableFactory
17.  def fill[A](n: Int)(elem: ⇒ A): GenIterable[A]

    Produces a collection containing the results of some element computation a number of times.

    Produces a collection containing the results of some element computation a number of times.

    n

      the number of elements contained in the collection.

    elem

      the element computation

    returns

      A collection that contains the results of `n` evaluations of `elem`.

    Definition Classes
      GenTraversableFactory
18.  def finalize(): Unit

    Called by the garbage collector on the receiver object when there are no more references to the object.

    Called by the garbage collector on the receiver object when there are no more references to the object.

    The details of when and if the `finalize` method is invoked, as well as the interaction between `finalize` and non-local returns and exceptions, are all platform dependent.

    Attributes
      protected[lang]
    Definition Classes
      AnyRef
    Annotations
      @throws( classOf[java.lang.Throwable] )
    Note

      not specified by SLS as a member of AnyRef

19.  final def getClass(): Class[_]

    Returns the runtime class representation of the object.

    Returns the runtime class representation of the object.

    returns

      a class object corresponding to the runtime type of the receiver.

    Definition Classes
      AnyRef → Any
    Annotations
      @native()
20.  def hashCode(): Int

    The hashCode method for reference types.

    The hashCode method for reference types. See hashCode in scala.Any.

    returns

      the hash code value for this object.

    Definition Classes
      AnyRef → Any
    Annotations
      @native()
21.  final def isInstanceOf[T0]: Boolean

    Test whether the dynamic type of the receiver object is `T0`.

    Test whether the dynamic type of the receiver object is `T0`.

    Note that the result of the test is modulo Scala's erasure semantics. Therefore the expression `1.isInstanceOf[String]` will return `false`, while the expression `List(1).isInstanceOf[List[String]]` will return `true`. In the latter example, because the type argument is erased as part of compilation it is not possible to check whether the contents of the list are of the specified type.

    returns

      `true` if the receiver object is an instance of erasure of type `T0`; `false` otherwise.

    Definition Classes
      Any
22.  def iterate[A](start: A, len: Int)(f: (A) ⇒ A): GenIterable[A]

    Produces a collection containing repeated applications of a function to a start value.

    Produces a collection containing repeated applications of a function to a start value.

    start

      the start value of the collection

    len

      the number of elements contained in the collection

    f

      the function that's repeatedly applied

    returns

      a collection with `len` values in the sequence `start, f(start), f(f(start)), ...`

    Definition Classes
      GenTraversableFactory
23.  final def ne(arg0: AnyRef): Boolean

    Equivalent to `!(this eq that)`.

    Equivalent to `!(this eq that)`.

    returns

      `true` if the argument is not a reference to the receiver object; `false` otherwise.

    Definition Classes
      AnyRef
24.  def newBuilder[A]: Builder[A, Iterable[A]]

    The default builder for ``Traversable`` objects.

    The default builder for ``Traversable`` objects.

    A

      the type of the collection's elements

    Definition Classes
      GenIterable → GenericCompanion
25.  final def notify(): Unit

    Wakes up a single thread that is waiting on the receiver object's monitor.

    Wakes up a single thread that is waiting on the receiver object's monitor.

    Definition Classes
      AnyRef
    Annotations
      @native()
    Note

      not specified by SLS as a member of AnyRef

26.  final def notifyAll(): Unit

    Wakes up all threads that are waiting on the receiver object's monitor.

    Wakes up all threads that are waiting on the receiver object's monitor.

    Definition Classes
      AnyRef
    Annotations
      @native()
    Note

      not specified by SLS as a member of AnyRef

27.  def range[T](start: T, end: T, step: T)(implicit arg0: Integral[T]): GenIterable[T]

    Produces a collection containing equally spaced values in some integer interval.

    Produces a collection containing equally spaced values in some integer interval.

    start

      the start value of the collection

    end

      the end value of the collection (the first value NOT contained)

    step

      the difference between successive elements of the collection (must be positive or negative)

    returns

      a collection with values `start, start + step, ...` up to, but excluding `end`

    Definition Classes
      GenTraversableFactory
28.  def range[T](start: T, end: T)(implicit arg0: Integral[T]): GenIterable[T]

    Produces a collection containing a sequence of increasing of integers.

    Produces a collection containing a sequence of increasing of integers.

    start

      the first element of the collection

    end

      the end value of the collection (the first value NOT contained)

    returns

      a collection with values `start, start + 1, ..., end - 1`

    Definition Classes
      GenTraversableFactory
29.  final def synchronized[T0](arg0: ⇒ T0): T0
    Definition Classes
      AnyRef
30.  def tabulate[A](n1: Int, n2: Int, n3: Int, n4: Int, n5: Int)(f: (Int, Int, Int, Int, Int) ⇒ A): GenIterable[GenIterable[GenIterable[GenIterable[GenIterable[A]]]]]

    Produces a five-dimensional collection containing values of a given function over ranges of integer values starting from 0.

    Produces a five-dimensional collection containing values of a given function over ranges of integer values starting from 0.

    n1

      the number of elements in the 1st dimension

    n2

      the number of elements in the 2nd dimension

    n3

      the number of elements in the 3nd dimension

    n4

      the number of elements in the 4th dimension

    n5

      the number of elements in the 5th dimension

    f

      The function computing element values

    returns

      A collection consisting of elements `f(i1, i2, i3, i4, i5)` for `0 <= i1 < n1`, `0 <= i2 < n2`, `0 <= i3 < n3`, `0 <= i4 < n4`, and `0 <= i5 < n5`.

    Definition Classes
      GenTraversableFactory
31.  def tabulate[A](n1: Int, n2: Int, n3: Int, n4: Int)(f: (Int, Int, Int, Int) ⇒ A): GenIterable[GenIterable[GenIterable[GenIterable[A]]]]

    Produces a four-dimensional collection containing values of a given function over ranges of integer values starting from 0.

    Produces a four-dimensional collection containing values of a given function over ranges of integer values starting from 0.

    n1

      the number of elements in the 1st dimension

    n2

      the number of elements in the 2nd dimension

    n3

      the number of elements in the 3nd dimension

    n4

      the number of elements in the 4th dimension

    f

      The function computing element values

    returns

      A collection consisting of elements `f(i1, i2, i3, i4)` for `0 <= i1 < n1`, `0 <= i2 < n2`, `0 <= i3 < n3`, and `0 <= i4 < n4`.

    Definition Classes
      GenTraversableFactory
32.  def tabulate[A](n1: Int, n2: Int, n3: Int)(f: (Int, Int, Int) ⇒ A): GenIterable[GenIterable[GenIterable[A]]]

    Produces a three-dimensional collection containing values of a given function over ranges of integer values starting from 0.

    Produces a three-dimensional collection containing values of a given function over ranges of integer values starting from 0.

    n1

      the number of elements in the 1st dimension

    n2

      the number of elements in the 2nd dimension

    n3

      the number of elements in the 3nd dimension

    f

      The function computing element values

    returns

      A collection consisting of elements `f(i1, i2, i3)` for `0 <= i1 < n1`, `0 <= i2 < n2`, and `0 <= i3 < n3`.

    Definition Classes
      GenTraversableFactory
33.  def tabulate[A](n1: Int, n2: Int)(f: (Int, Int) ⇒ A): GenIterable[GenIterable[A]]

    Produces a two-dimensional collection containing values of a given function over ranges of integer values starting from 0.

    Produces a two-dimensional collection containing values of a given function over ranges of integer values starting from 0.

    n1

      the number of elements in the 1st dimension

    n2

      the number of elements in the 2nd dimension

    f

      The function computing element values

    returns

      A collection consisting of elements `f(i1, i2)` for `0 <= i1 < n1` and `0 <= i2 < n2`.

    Definition Classes
      GenTraversableFactory
34.  def tabulate[A](n: Int)(f: (Int) ⇒ A): GenIterable[A]

    Produces a collection containing values of a given function over a range of integer values starting from 0.

    Produces a collection containing values of a given function over a range of integer values starting from 0.

    n

      The number of elements in the collection

    f

      The function computing element values

    returns

      A collection consisting of elements `f(0), ..., f(n -1)`

    Definition Classes
      GenTraversableFactory
35.  def toString(): String

    Creates a String representation of this object.

    Creates a String representation of this object. The default representation is platform dependent. On the java platform it is the concatenation of the class name, "@", and the object's hashcode in hexadecimal.

    returns

      a String representation of the object.

    Definition Classes
      AnyRef → Any
36.  final def wait(): Unit
    Definition Classes
      AnyRef
    Annotations
      @throws( ... )
37.  final def wait(arg0: Long, arg1: Int): Unit
    Definition Classes
      AnyRef
    Annotations
      @throws( ... )
38.  final def wait(arg0: Long): Unit
    Definition Classes
      AnyRef
    Annotations
      @throws( ... ) @native()

### Inherited from GenTraversableFactory[GenIterable]

### Inherited from GenericCompanion[GenIterable]

### Inherited from AnyRef

### Inherited from Any

### Ungrouped