Scala Standard Library2.13.15 < 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.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

c

scala.collection

# IterableOnceExtensionMethods

###

#### final class IterableOnceExtensionMethods[A] extends AnyVal

Source
  IterableOnce.scala

Linear Supertypes
AnyVal, Any
Type Hierarchy

Ordering

1. Alphabetic
2. By Inheritance

Inherited

1. IterableOnceExtensionMethods
2. AnyVal
3. Any

Implicitly

1. by any2stringadd
2. by StringFormat
3. by Ensuring
4. by ArrowAssoc

1. Hide All
2. Show All

Visibility

1. Public
2. Protected

### Instance Constructors

1.  new IterableOnceExtensionMethods(it: IterableOnce[A])

### 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
     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
     Any
3.  def +(other: String): String
   Implicit
     This member is added by an implicit conversion from IterableOnceExtensionMethods[A] toany2stringadd[IterableOnceExtensionMethods[A]] performed by method any2stringadd in scala.Predef.
   Definition Classes
     any2stringadd
4.  def ->[B](y: B): (IterableOnceExtensionMethods[A], B)
   Implicit
     This member is added by an implicit conversion from IterableOnceExtensionMethods[A] toArrowAssoc[IterableOnceExtensionMethods[A]] performed by method ArrowAssoc in scala.Predef.
   Definition Classes
     ArrowAssoc
   Annotations
     @inline()
5.  final def ==(arg0: Any): Boolean

   Test two objects for equality.

   Test two objects for equality. 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
     Any
6.  final def asInstanceOf[T0]: T0

   Forces the compiler to treat the receiver object as having type `T0`, even though doing so may violate type safety.

   Forces the compiler to treat the receiver object as having type `T0`, even though doing so may violate type safety.

   This method is useful when you believe you have type information the compiler doesn't, and it also isn't possible to check the type at runtime. In such situations, skipping type safety is the only option.

   It is platform dependent whether `asInstanceOf` has any effect at runtime. It might do a runtime type test on the erasure of `T0`, insert a conversion (such as boxing/unboxing), fill in a default value, or do nothing at all.

   In particular, `asInstanceOf` is not a type test. It does **not** mean:

       this match {
        case x: T0 => x
        case _     => throw ClassCastException("...")

   Use pattern matching or isInstanceOf for type testing instead.

   Situations where `asInstanceOf` is useful:

   - when flow analysis fails to deduce `T0` automatically
   - when down-casting a type parameter or an abstract type member (which cannot be checked at runtime due to type erasure) If there is any doubt and you are able to type test instead, you should do so.

   Be careful of using `asInstanceOf` when `T0` is a primitive type. When `T0` is primitive, `asInstanceOf` may insert a conversion instead of a type test. If your intent is to convert, use a `toT` method (`x.toChar`, `x.toByte`, etc.).

   returns

     the receiver object.

   Definition Classes
     Any
   Exceptions thrown

     `ClassCastException` if the receiver is not an instance of the erasure of `T0`, if that can be checked on this platform

7.  def ensuring(cond: (IterableOnceExtensionMethods[A]) => Boolean, msg: => Any): IterableOnceExtensionMethods[A]
   Implicit
     This member is added by an implicit conversion from IterableOnceExtensionMethods[A] toEnsuring[IterableOnceExtensionMethods[A]] performed by method Ensuring in scala.Predef.
   Definition Classes
     Ensuring
8.  def ensuring(cond: (IterableOnceExtensionMethods[A]) => Boolean): IterableOnceExtensionMethods[A]
   Implicit
     This member is added by an implicit conversion from IterableOnceExtensionMethods[A] toEnsuring[IterableOnceExtensionMethods[A]] performed by method Ensuring in scala.Predef.
   Definition Classes
     Ensuring
9.  def ensuring(cond: Boolean, msg: => Any): IterableOnceExtensionMethods[A]
   Implicit
     This member is added by an implicit conversion from IterableOnceExtensionMethods[A] toEnsuring[IterableOnceExtensionMethods[A]] performed by method Ensuring in scala.Predef.
   Definition Classes
     Ensuring
10.  def ensuring(cond: Boolean): IterableOnceExtensionMethods[A]
    Implicit
      This member is added by an implicit conversion from IterableOnceExtensionMethods[A] toEnsuring[IterableOnceExtensionMethods[A]] performed by method Ensuring in scala.Predef.
    Definition Classes
      Ensuring
11.  def getClass(): Class[_ <: AnyVal]

    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
      AnyVal → Any
12.  final def isInstanceOf[T0]: Boolean

    Test whether the dynamic type of the receiver object has the same erasure as `T0`.

    Test whether the dynamic type of the receiver object has the same erasure as `T0`.

    Depending on what `T0` is, the test is done in one of the below ways:

    - `T0` is a non-parameterized class type, e.g. `BigDecimal`: this method returns `true` if the value of the receiver object is a `BigDecimal` or a subtype of `BigDecimal`.
    - `T0` is a parameterized class type, e.g. `List[Int]`: this method returns `true` if the value of the receiver object is some `List[X]` for any `X`. For example, `List(1, 2, 3).isInstanceOf[List[String]]` will return true.
    - `T0` is some singleton type `x.type` or literal `x`: this method returns `this.eq(x)`. For example, `x.isInstanceOf[1]` is equivalent to `x.eq(1)`
    - `T0` is an intersection `X with Y` or `X & Y: this method is equivalent to` x.isInstanceOf[X] && x.isInstanceOf[Y]``
    - `T0` is a union `X | Y`: this method is equivalent to `x.isInstanceOf[X] || x.isInstanceOf[Y]`
    - `T0` is a type parameter or an abstract type member: this method is equivalent to `isInstanceOf[U]` where `U` is `T0`'s upper bound, `Any` if `T0` is unbounded. For example, `x.isInstanceOf[A]` where `A` is an unbounded type parameter will return true for any value of `x`.

    This is exactly equivalent to the type pattern `_: T0`

    returns

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

    Definition Classes
      Any
    Note

      due to the unexpectedness of `List(1, 2, 3).isInstanceOf[List[String]]` returning true and `x.isInstanceOf[A]` where `A` is a type parameter or abstract member returning true, these forms issue a warning.

13.  def toString(): String

    Returns a string representation of the object.

    Returns a string representation of the object.

    The default representation is platform dependent.

    returns

      a string representation of the object.

    Definition Classes
      Any

### Deprecated Value Members

1.  def /:[B](z: B)(op: (B, A) => B): B
   Annotations
     @deprecated @inline()
   Deprecated

     (Since version 2.13.0) Use .iterator.foldLeft instead

2.  def :\[B](z: B)(op: (A, B) => B): B
   Annotations
     @deprecated @inline()
   Deprecated

     (Since version 2.13.0) Use .iterator.foldRight instead

3.  def collectFirst[B](f: PartialFunction[A, B]): Option[B]
   Annotations
     @deprecated
   Deprecated

     (Since version 2.13.0) Use .iterator.collectFirst(...) instead

4.  def copyToBuffer(dest: Buffer[A]): Unit
   Annotations
     @deprecated
   Deprecated

     (Since version 2.13.0) Use .iterator.copyToBuffer(...) instead

5.  def count(f: (A) => Boolean): Int
   Annotations
     @deprecated
   Deprecated

     (Since version 2.13.0) Use .iterator.count(...) instead

6.  def exists(f: (A) => Boolean): Boolean
   Annotations
     @deprecated
   Deprecated

     (Since version 2.13.0) Use .iterator.exists(...) instead

7.  def filter(f: (A) => Boolean): Iterator[A]
   Annotations
     @deprecated
   Deprecated

     (Since version 2.13.0) Use .iterator.filter(...) instead

8.  def find(p: (A) => Boolean): Option[A]
   Annotations
     @deprecated
   Deprecated

     (Since version 2.13.0) Use .iterator.find instead

9.  def flatMap[B](f: (A) => IterableOnce[B]): IterableOnce[B]
   Annotations
     @deprecated
   Deprecated

     (Since version 2.13.0) Use .iterator.flatMap instead or consider requiring an Iterable

10.  def fold[A1 >: A](z: A1)(op: (A1, A1) => A1): A1
    Annotations
      @deprecated
    Deprecated

      (Since version 2.13.0) Use .iterator.fold instead

11.  def foldLeft[B](z: B)(op: (B, A) => B): B
    Annotations
      @deprecated @inline()
    Deprecated

      (Since version 2.13.0) Use .iterator.foldLeft instead

12.  def foldRight[B](z: B)(op: (A, B) => B): B
    Annotations
      @deprecated @inline()
    Deprecated

      (Since version 2.13.0) Use .iterator.foldRight instead

13.  def forall(f: (A) => Boolean): Boolean
    Annotations
      @deprecated
    Deprecated

      (Since version 2.13.0) Use .iterator.forall(...) instead

14.  def foreach[U](f: (A) => U): Unit
    Annotations
      @deprecated @inline()
    Deprecated

      (Since version 2.13.0) Use .iterator.foreach(...) instead

15.  def formatted(fmtstr: String): String

    Returns string formatted according to given `format` string.

    Returns string formatted according to given `format` string. Format strings are as for `String.format` (@see java.lang.String.format).

    Implicit
      This member is added by an implicit conversion from IterableOnceExtensionMethods[A] toStringFormat[IterableOnceExtensionMethods[A]] performed by method StringFormat in scala.Predef.
    Definition Classes
      StringFormat
    Annotations
      @deprecated @inline()
    Deprecated

      (Since version 2.12.16) Use `formatString.format(value)` instead of `value.formatted(formatString)`, or use the `f""` string interpolator. In Java 15 and later, `formatted` resolves to the new method in String which has reversed parameters.

16.  def isEmpty: Boolean
    Annotations
      @deprecated
    Deprecated

      (Since version 2.13.0) Use .iterator.isEmpty instead

17.  def map[B](f: (A) => B): IterableOnce[B]
    Annotations
      @deprecated
    Deprecated

      (Since version 2.13.0) Use .iterator.map instead or consider requiring an Iterable

18.  def max(implicit ord: math.Ordering[A]): A
    Annotations
      @deprecated
    Deprecated

      (Since version 2.13.0) Use .iterator.max instead

19.  def maxBy[B](f: (A) => B)(implicit cmp: math.Ordering[B]): A
    Annotations
      @deprecated
    Deprecated

      (Since version 2.13.0) Use .iterator.maxBy(...) instead

20.  def min(implicit ord: math.Ordering[A]): A
    Annotations
      @deprecated
    Deprecated

      (Since version 2.13.0) Use .iterator.min instead

21.  def minBy[B](f: (A) => B)(implicit cmp: math.Ordering[B]): A
    Annotations
      @deprecated
    Deprecated

      (Since version 2.13.0) Use .iterator.minBy(...) instead

22.  def mkString: String
    Annotations
      @deprecated
    Deprecated

      (Since version 2.13.0) Use .iterator.mkString instead

23.  def mkString(sep: String): String
    Annotations
      @deprecated
    Deprecated

      (Since version 2.13.0) Use .iterator.mkString instead

24.  def mkString(start: String, sep: String, end: String): String
    Annotations
      @deprecated
    Deprecated

      (Since version 2.13.0) Use .iterator.mkString instead

25.  def nonEmpty: Boolean
    Annotations
      @deprecated
    Deprecated

      (Since version 2.13.0) Use .iterator.nonEmpty instead

26.  def product(implicit num: math.Numeric[A]): A
    Annotations
      @deprecated
    Deprecated

      (Since version 2.13.0) Use .iterator.product instead

27.  def reduce(f: (A, A) => A): A
    Annotations
      @deprecated
    Deprecated

      (Since version 2.13.0) Use .iterator.reduce(...) instead

28.  def reduceLeft(f: (A, A) => A): A
    Annotations
      @deprecated
    Deprecated

      (Since version 2.13.0) Use .iterator.reduceLeft(...) instead

29.  def reduceLeftOption(f: (A, A) => A): Option[A]
    Annotations
      @deprecated
    Deprecated

      (Since version 2.13.0) Use .iterator.reduceLeftOption(...) instead

30.  def reduceOption(f: (A, A) => A): Option[A]
    Annotations
      @deprecated
    Deprecated

      (Since version 2.13.0) Use .iterator.reduceOption(...) instead

31.  def reduceRight(f: (A, A) => A): A
    Annotations
      @deprecated
    Deprecated

      (Since version 2.13.0) Use .iterator.reduceRight(...) instead

32.  def reduceRightOption(f: (A, A) => A): Option[A]
    Annotations
      @deprecated
    Deprecated

      (Since version 2.13.0) Use .iterator.reduceRightOption(...) instead

33.  def sameElements[B >: A](that: IterableOnce[B]): Boolean
    Annotations
      @deprecated
    Deprecated

      (Since version 2.13.0) Use .iterator.sameElements instead

34.  def size: Int
    Annotations
      @deprecated
    Deprecated

      (Since version 2.13.0) Use .iterator.size instead

35.  def sum(implicit num: math.Numeric[A]): A
    Annotations
      @deprecated
    Deprecated

      (Since version 2.13.0) Use .iterator.sum instead

36.  def to[C1](factory: Factory[A, C1]): C1
    Annotations
      @deprecated
    Deprecated

      (Since version 2.13.0) Use .iterator.to(factory) instead

37.  def toArray[B >: A](implicit arg0: ClassTag[B]): Array[B]
    Annotations
      @deprecated
    Deprecated

      (Since version 2.13.0) Use .iterator.toArray

38.  def toBuffer[B >: A]: Buffer[B]
    Annotations
      @deprecated
    Deprecated

      (Since version 2.13.0) Use .iterator.to(ArrayBuffer) instead

39.  def toIndexedSeq: IndexedSeq[A]
    Annotations
      @deprecated
    Deprecated

      (Since version 2.13.0) Use .iterator.toIndexedSeq instead

40.  final def toIterable: Iterable[A]
    Annotations
      @deprecated @inline()
    Deprecated

      (Since version 2.13.0) Use .iterator.to(Iterable) instead

41.  def toIterator: Iterator[A]
    Annotations
      @deprecated @inline()
    Deprecated

      (Since version 2.13.0) Use .iterator instead

42.  def toList: immutable.List[A]
    Annotations
      @deprecated
    Deprecated

      (Since version 2.13.0) Use .iterator.to(List) instead

43.  def toMap[K, V](implicit ev: <:<[A, (K, V)]): immutable.Map[K, V]
    Annotations
      @deprecated
    Deprecated

      (Since version 2.13.0) Use .iterator.to(Map) instead

44.  def toSeq: immutable.Seq[A]
    Annotations
      @deprecated @inline()
    Deprecated

      (Since version 2.13.0) Use .iterator.to(Seq) instead

45.  def toSet[B >: A]: immutable.Set[B]
    Annotations
      @deprecated @inline()
    Deprecated

      (Since version 2.13.0) Use .iterator.to(Set) instead

46.  def toStream: immutable.Stream[A]
    Annotations
      @deprecated @inline()
    Deprecated

      (Since version 2.13.0) Use .iterator.to(LazyList) instead

47.  final def toTraversable: Traversable[A]
    Annotations
      @deprecated @inline()
    Deprecated

      (Since version 2.13.0) Use .iterator.to(Iterable) instead

48.  def toVector: immutable.Vector[A]
    Annotations
      @deprecated @inline()
    Deprecated

      (Since version 2.13.0) Use .iterator.to(Vector) instead

49.  def withFilter(f: (A) => Boolean): Iterator[A]
    Annotations
      @deprecated
    Deprecated

      (Since version 2.13.0) Use .iterator.withFilter(...) instead

50.  def →[B](y: B): (IterableOnceExtensionMethods[A], B)
    Implicit
      This member is added by an implicit conversion from IterableOnceExtensionMethods[A] toArrowAssoc[IterableOnceExtensionMethods[A]] performed by method ArrowAssoc in scala.Predef.
    Definition Classes
      ArrowAssoc
    Annotations
      @deprecated
    Deprecated

      (Since version 2.13.0) Use `->` instead. If you still wish to display it as one character, consider using a font with programming ligatures such as Fira Code.

### Inherited from AnyVal

### Inherited from Any

### Inherited by implicit conversion any2stringadd fromIterableOnceExtensionMethods[A] to any2stringadd[IterableOnceExtensionMethods[A]]

### Inherited by implicit conversion StringFormat fromIterableOnceExtensionMethods[A] to StringFormat[IterableOnceExtensionMethods[A]]

### Inherited by implicit conversion Ensuring fromIterableOnceExtensionMethods[A] to Ensuring[IterableOnceExtensionMethods[A]]

### Inherited by implicit conversion ArrowAssoc fromIterableOnceExtensionMethods[A] to ArrowAssoc[IterableOnceExtensionMethods[A]]

### Ungrouped