Scala Standard Library2.12.21 < 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 convert
  Definition Classes
    collection
- AsJavaConverters
- AsScalaConverters
- DecorateAsJava
- DecorateAsScala
- ImplicitConversions
- ImplicitConversionsToJava
- ImplicitConversionsToScala
- ToJavaImplicits
- ToScalaImplicits
- WrapAsJava
- WrapAsScala
- Wrappers

o

scala.collection.convert

# ImplicitConversionsToJava 

###

#### object ImplicitConversionsToJava extends ToJavaImplicits

Convenience for miscellaneous implicit conversions from Scala to Java collections API.

It is recommended to use explicit conversions provided by collection.JavaConverters instead. Implicit conversions may cause unexpected issues, see ImplicitConversions.

Source
  ImplicitConversions.scala

Linear Supertypes
ToJavaImplicits, AnyRef, Any
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2. By Inheritance

Inherited

1. ImplicitConversionsToJava
2. ToJavaImplicits
3. AnyRef
4. Any

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Visibility

1. Public
2. All

### 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.  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`.

5.  implicit def buffer AsJavaList[A](b: Buffer[A]): java.util.List[A]

   Implicitly converts a Scala mutable `Buffer` to a Java `List`.

   Implicitly converts a Scala mutable `Buffer` to a Java `List`.

   Definition Classes
     ToJavaImplicits
   See also

     AsJavaConverters.bufferAsJavaList

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( ... ) @native()
   Note

     not specified by SLS as a member of AnyRef

7.  implicit def collection asJava[A](it: Iterable[A]): Collection[A]

   Implicitly converts a Scala `Iterable` to an immutable Java `Collection`.

   Implicitly converts a Scala `Iterable` to an immutable Java `Collection`.

   Definition Classes
     ToJavaImplicits
   See also

     AsJavaConverters.asJavaCollection

8.  implicit def dictionary asJava[A, B](m: mutable.Map[A, B]): Dictionary[A, B]

   Implicitly converts a Scala mutable `Map` to a Java `Dictionary`.

   Implicitly converts a Scala mutable `Map` to a Java `Dictionary`.

   Definition Classes
     ToJavaImplicits
   See also

     AsJavaConverters.asJavaDictionary

9.  implicit def enumeration asJava[A](it: Iterator[A]): java.util.Enumeration[A]

   Implicitly converts a Scala `Iterator` to a Java `Enumeration`.

   Implicitly converts a Scala `Iterator` to a Java `Enumeration`.

   Definition Classes
     ToJavaImplicits
   See also

     AsJavaConverters.asJavaEnumeration

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: 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
12.  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

13.  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()
14.  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()
15.  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
16.  implicit def iterable asJava[A](i: Iterable[A]): java.lang.Iterable[A]

    Implicitly converts a Scala `Iterable` to a Java `Iterable`.

    Implicitly converts a Scala `Iterable` to a Java `Iterable`.

    Definition Classes
      ToJavaImplicits
    See also

      AsJavaConverters.asJavaIterable

17.  implicit def iterator asJava[A](it: Iterator[A]): java.util.Iterator[A]

    Implicitly converts a Scala `Iterator` to a Java `Iterator`.

    Implicitly converts a Scala `Iterator` to a Java `Iterator`.

    Definition Classes
      ToJavaImplicits
    See also

      AsJavaConverters.asJavaIterator

18.  implicit def map AsJavaConcurrentMap[A, B](m: concurrent.Map[A, B]): ConcurrentMap[A, B]

    Implicitly converts a Scala mutable `concurrent.Map` to a Java `ConcurrentMap`.

    Implicitly converts a Scala mutable `concurrent.Map` to a Java `ConcurrentMap`.

    Definition Classes
      ToJavaImplicits
    See also

      AsJavaConverters.mapAsJavaConcurrentMap

19.  implicit def map AsJavaMap[A, B](m: Map[A, B]): java.util.Map[A, B]

    Implicitly converts a Scala `Map` to a Java `Map`.

    Implicitly converts a Scala `Map` to a Java `Map`.

    Definition Classes
      ToJavaImplicits
    See also

      AsJavaConverters.mapAsJavaMap

20.  implicit def mutableMap AsJavaMap[A, B](m: mutable.Map[A, B]): java.util.Map[A, B]

    Implicitly converts a Scala mutable `Map` to a Java `Map`.

    Implicitly converts a Scala mutable `Map` to a Java `Map`.

    Definition Classes
      ToJavaImplicits
    See also

      AsJavaConverters.mutableMapAsJavaMap

21.  implicit def mutableSeq AsJavaList[A](seq: mutable.Seq[A]): java.util.List[A]

    Implicitly converts a Scala mutable `Seq` to a Java `List`.

    Implicitly converts a Scala mutable `Seq` to a Java `List`.

    Definition Classes
      ToJavaImplicits
    See also

      AsJavaConverters.mutableSeqAsJavaList

22.  implicit def mutableSet AsJavaSet[A](s: mutable.Set[A]): java.util.Set[A]

    Implicitly converts a Scala mutable `Set` to a Java `Set`.

    Implicitly converts a Scala mutable `Set` to a Java `Set`.

    Definition Classes
      ToJavaImplicits
    See also

      AsJavaConverters.mutableSetAsJavaSet

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.  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

25.  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

26.  implicit def seq AsJavaList[A](seq: Seq[A]): java.util.List[A]

    Implicitly converts a Scala `Seq` to a Java `List`.

    Implicitly converts a Scala `Seq` to a Java `List`.

    Definition Classes
      ToJavaImplicits
    See also

      AsJavaConverters.seqAsJavaList

27.  implicit def set AsJavaSet[A](s: Set[A]): java.util.Set[A]

    Implicitly converts a Scala `Set` to a Java `Set`.

    Implicitly converts a Scala `Set` to a Java `Set`.

    Definition Classes
      ToJavaImplicits
    See also

      AsJavaConverters.setAsJavaSet

28.  final def synchronized[T0](arg0: ⇒ T0): T0
    Definition Classes
      AnyRef
29.  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
30.  final def wait(): Unit
    Definition Classes
      AnyRef
    Annotations
      @throws( ... )
31.  final def wait(arg0: Long, arg1: Int): Unit
    Definition Classes
      AnyRef
    Annotations
      @throws( ... )
32.  final def wait(arg0: Long): Unit
    Definition Classes
      AnyRef
    Annotations
      @throws( ... ) @native()

### Inherited from ToJavaImplicits

### Inherited from AnyRef

### Inherited from Any

### Ungrouped