Scala Standard Library2.13.6 < 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.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.collection.parallel` - Parallel collections (scala-parallel-collections.jar)
  - `scala.util.parsing` - Parser combinators (scala-parser-combinators.jar)
  - `scala.swing` - A convenient wrapper around Java's GUI framework called Swing (scala-swing.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
  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
- +:
- :+
- AbstractIndexedSeqView
- AbstractIterable
- AbstractIterator
- AbstractMap
- AbstractMapView
- AbstractSeq
- AbstractSeqView
- AbstractSet
- AbstractView
- AnyStepper
- ArrayOps
- BitSet
- BitSetOps
- BufferedIterator
- BuildFrom
- BuildFromLowPriority1
- BuildFromLowPriority2
- ClassTagIterableFactory
- ClassTagSeqFactory
- DefaultMap
- DoubleStepper
- EvidenceIterableFactory
- EvidenceIterableFactoryDefaults
- Factory
- Hashing
- IndexedSeq
- IndexedSeqOps
- IndexedSeqView
- IntStepper
- Iterable
- IterableFactory
- IterableFactoryDefaults
- IterableOnce
- IterableOnceExtensionMethods
- IterableOnceOps
- IterableOps
- Iterator
- JavaConverters
- LazyZip2
- LazyZip3
- LazyZip4
- LinearSeq
- LinearSeqOps
- LongStepper
- Map
- MapFactory
- MapFactoryDefaults
- MapOps
- MapView
- MapViewFactory
- Searching
- Seq
- SeqFactory
- SeqMap
- SeqOps
- SeqView
- Set
- SetOps
- SortedIterableFactory
- SortedMap
- SortedMapFactory
- SortedMapFactoryDefaults
- SortedMapOps
- SortedOps
- SortedSet
- SortedSetFactoryDefaults
- SortedSetOps
- SpecificIterableFactory
- Stepper
- StepperShape
- StepperShapeLowPriority1
- StepperShapeLowPriority2
- StrictOptimizedClassTagSeqFactory
- StrictOptimizedIterableOps
- StrictOptimizedLinearSeqOps
- StrictOptimizedMapOps
- StrictOptimizedSeqFactory
- StrictOptimizedSeqOps
- StrictOptimizedSetOps
- StrictOptimizedSortedMapOps
- StrictOptimizedSortedSetOps
- StringOps
- StringView
- View
- WithFilter

o

scala.collection

# Iterator

###
Companion trait Iterator

#### object Iterator extends IterableFactory[Iterator]

Annotations
  @SerialVersionUID()
Source
  Iterator.scala

Linear Supertypes
IterableFactory[Iterator], java.io.Serializable, AnyRef, Any

Ordering

1. Alphabetic
2. By Inheritance

Inherited

1. Iterator
2. IterableFactory
3. Serializable
4. AnyRef
5. Any

1. Hide All
2. Show All

Visibility

1. Public
2. Protected

### 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 apply[A](xs: A*): Iterator[A]

   Creates a collection with the specified elements.

   Creates a collection with the specified elements.

   A

     the type of the collection's elements

   returns

     a new collection with elements `elems`

   Definition Classes
     Iterator → IterableFactory
5.  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`.

6.  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(classOf[java.lang.CloneNotSupportedException]) @native()
   Note

     not specified by SLS as a member of AnyRef

7.  def concat[A](xss: Iterable[A]*): Iterator[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
     IterableFactory
8.  def continually[A](elem: => A): Iterator[A]

   Creates an infinite-length iterator returning the results of evaluating an expression.

   Creates an infinite-length iterator returning the results of evaluating an expression. The expression is recomputed for every element.

   elem

     the element computation.

   returns

     the iterator containing an infinite number of results of evaluating `elem`.

9.  final def empty[T]: Iterator[T]

   The iterator which produces no values.

   The iterator which produces no values.

   Definition Classes
     Iterator → IterableFactory
   Annotations
     @inline()
10.  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
11.  def equals(arg0: AnyRef): 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
12.  def fill[A](len: Int)(elem: => A): Iterator[A]

    Creates iterator that produces the results of some element computation a number of times.

    Creates iterator that produces the results of some element computation a number of times.

    len

      the number of elements returned by the iterator.

    elem

      the element computation

    returns

      An iterator that produces the results of `n` evaluations of `elem`.

    Definition Classes
      Iterator → IterableFactory
13.  def fill[A](n1: Int, n2: Int, n3: Int, n4: Int, n5: Int)(elem: => A): Iterator[Iterator[Iterator[Iterator[Iterator[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 3rd 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
      IterableFactory
14.  def fill[A](n1: Int, n2: Int, n3: Int, n4: Int)(elem: => A): Iterator[Iterator[Iterator[Iterator[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 3rd 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
      IterableFactory
15.  def fill[A](n1: Int, n2: Int, n3: Int)(elem: => A): Iterator[Iterator[Iterator[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 3rd dimension

    elem

      the element computation

    returns

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

    Definition Classes
      IterableFactory
16.  def fill[A](n1: Int, n2: Int)(elem: => A): Iterator[Iterator[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
      IterableFactory
17.  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

18.  def from(start: Int, step: Int): Iterator[Int]

    Creates an infinite-length iterator returning values equally spaced apart.

    Creates an infinite-length iterator returning values equally spaced apart.

    start

      the start value of the iterator

    step

      the increment between successive values

    returns

      the iterator producing the infinite sequence of values `start, start + 1 * step, start + 2 * step, ...`

19.  def from(start: Int): Iterator[Int]

    Creates an infinite-length iterator which returns successive values from some start value.

    Creates an infinite-length iterator which returns successive values from some start value.

    start

      the start value of the iterator

    returns

      the iterator producing the infinite sequence of values `start, start + 1, start + 2, ...`

20.  def from[A](source: IterableOnce[A]): Iterator[A]

    Creates a target collection from an existing source collection

    Creates a target collection from an existing source collection

    A

      the type of the collection’s elements

    source

      Source collection

    returns

      a new collection with the elements of `source`

    Definition Classes
      Iterator → IterableFactory
21.  final def getClass(): Class[_ <: AnyRef]

    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()
22.  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()
23.  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
24.  implicit def iterableFactory[A]: Factory[A, Iterator[A]]
    Definition Classes
      IterableFactory
25.  def iterate[T](start: T)(f: (T) => T): Iterator[T]

    Creates an infinite iterator that repeatedly applies a given function to the previous result.

    Creates an infinite iterator that repeatedly applies a given function to the previous result.

    start

      the start value of the iterator

    f

      the function that's repeatedly applied

    returns

      the iterator producing the infinite sequence of values `start, f(start), f(f(start)), ...`

26.  def iterate[A](start: A, len: Int)(f: (A) => A): Iterator[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
      IterableFactory
27.  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
28.  def newBuilder[A]: Builder[A, Iterator[A]]

    A

      the type of the collection’s elements

    returns

      A builder for `Iterable` objects.

    Definition Classes
      Iterator → IterableFactory
29.  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

30.  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

31.  def range(start: Int, end: Int, step: Int): Iterator[Int]

    An iterator producing equally spaced values in some integer interval.

    An iterator producing equally spaced values in some integer interval.

    start

      the start value of the iterator

    end

      the end value of the iterator (the first value NOT returned)

    step

      the increment value of the iterator (must be positive or negative)

    returns

      the iterator producing values `start, start + step, ...` up to, but excluding `end`

32.  def range(start: Int, end: Int): Iterator[Int]

    Creates nn iterator returning successive values in some integer interval.

    Creates nn iterator returning successive values in some integer interval.

    start

      the start value of the iterator

    end

      the end value of the iterator (the first value NOT returned)

    returns

      the iterator producing values `start, start + 1, ..., end - 1`

33.  def range[A](start: A, end: A, step: A)(implicit arg0: Integral[A]): Iterator[A]

    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
      IterableFactory
34.  def range[A](start: A, end: A)(implicit arg0: Integral[A]): Iterator[A]

    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
      IterableFactory
35.  def single[A](a: A): Iterator[A]
36.  final def synchronized[T0](arg0: => T0): T0

    Executes the code in `body` with an exclusive lock on `this`.

    Executes the code in `body` with an exclusive lock on `this`.

    returns

      the result of `body`

    Definition Classes
      AnyRef
37.  def tabulate[A](end: Int)(f: (Int) => A): Iterator[A]

    Creates an iterator producing the values of a given function over a range of integer values starting from 0.

    Creates an iterator producing the values of a given function over a range of integer values starting from 0.

    end

      The number of elements returned by the iterator

    f

      The function computing element values

    returns

      An iterator that produces the values `f(0), ..., f(n -1)`.

    Definition Classes
      Iterator → IterableFactory
38.  def tabulate[A](n1: Int, n2: Int, n3: Int, n4: Int, n5: Int)(f: (Int, Int, Int, Int, Int) => A): Iterator[Iterator[Iterator[Iterator[Iterator[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 3rd 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
      IterableFactory
39.  def tabulate[A](n1: Int, n2: Int, n3: Int, n4: Int)(f: (Int, Int, Int, Int) => A): Iterator[Iterator[Iterator[Iterator[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 3rd 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
      IterableFactory
40.  def tabulate[A](n1: Int, n2: Int, n3: Int)(f: (Int, Int, Int) => A): Iterator[Iterator[Iterator[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 3rd 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
      IterableFactory
41.  def tabulate[A](n1: Int, n2: Int)(f: (Int, Int) => A): Iterator[Iterator[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
      IterableFactory
42.  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
43.  def unfold[A, S](init: S)(f: (S) => Option[(A, S)]): Iterator[A]

    Creates an Iterator that uses a function `f` to produce elements of type `A` and update an internal state of type `S`.

    Creates an Iterator that uses a function `f` to produce elements of type `A` and update an internal state of type `S`.

    A

      Type of the elements

    S

      Type of the internal state

    init

      State initial value

    f

      Computes the next element (or returns `None` to signal the end of the collection)

    returns

      an Iterator that produces elements using `f` until `f` returns `None`

    Definition Classes
      Iterator → IterableFactory
44.  final def wait(): Unit

    See https://docs.oracle.com/javase/8/docs/api/java/lang/Object.html#wait--.

    See https://docs.oracle.com/javase/8/docs/api/java/lang/Object.html#wait--.

    Definition Classes
      AnyRef
    Annotations
      @throws(classOf[java.lang.InterruptedException])
    Note

      not specified by SLS as a member of AnyRef

45.  final def wait(arg0: Long, arg1: Int): Unit

    See https://docs.oracle.com/javase/8/docs/api/java/lang/Object.html#wait-long-int-

    See https://docs.oracle.com/javase/8/docs/api/java/lang/Object.html#wait-long-int-

    Definition Classes
      AnyRef
    Annotations
      @throws(classOf[java.lang.InterruptedException])
    Note

      not specified by SLS as a member of AnyRef

46.  final def wait(arg0: Long): Unit

    See https://docs.oracle.com/javase/8/docs/api/java/lang/Object.html#wait-long-.

    See https://docs.oracle.com/javase/8/docs/api/java/lang/Object.html#wait-long-.

    Definition Classes
      AnyRef
    Annotations
      @throws(classOf[java.lang.InterruptedException]) @native()
    Note

      not specified by SLS as a member of AnyRef

### Inherited from IterableFactory[Iterator]

### Inherited from java.io.Serializable

### Inherited from AnyRef

### Inherited from Any

### Ungrouped