Scala Standard Library2.13.4 < 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 concurrent

  This package object contains primitives for concurrent and parallel programming.

  This package object contains primitives for concurrent and parallel programming.

  #### Guide

  A more detailed guide to Futures and Promises, including discussion and examples can be found at http://docs.scala-lang.org/overviews/core/futures.html.

  #### Common Imports

  When working with Futures, you will often find that importing the whole concurrent package is convenient:

      import scala.concurrent._

  When using things like `Future`s, it is often required to have an implicit `ExecutionContext` in scope. The general advice for these implicits are as follows.

  If the code in question is a class or method definition, and no `ExecutionContext` is available, request one from the caller by adding an implicit parameter list:

      def myMethod(myParam: MyType)(implicit ec: ExecutionContext) = …
      //Or
      class MyClass(myParam: MyType)(implicit ec: ExecutionContext) { … }

  This allows the caller of the method, or creator of the instance of the class, to decide which `ExecutionContext` should be used.

  For typical REPL usage and experimentation, importing the global `ExecutionContext` is often desired.

      import scala.concurrent.ExcutionContext.Implicits.global

  #### Specifying Durations

  Operations often require a duration to be specified. A duration DSL is available to make defining these easier:

      import scala.concurrent.duration._
      val d: Duration = 10.seconds

  #### Using Futures For Non-blocking Computation

  Basic use of futures is easy with the factory method on Future, which executes a provided function asynchronously, handing you back a future result of that function without blocking the current thread. In order to create the Future you will need either an implicit or explicit ExecutionContext to be provided:

      import scala.concurrent._
      import ExecutionContext.Implicits.global  // implicit execution context

      val firstZebra: Future[Int] = Future {
        val words = Files.readAllLines("/etc/dictionaries-common/words").asScala
        words.indexOfSlice("zebra")
      }

  #### Avoid Blocking

  Although blocking is possible in order to await results (with a mandatory timeout duration):

      import scala.concurrent.duration._
      Await.result(firstZebra, 10.seconds)

  and although this is sometimes necessary to do, in particular for testing purposes, blocking in general is discouraged when working with Futures and concurrency in order to avoid potential deadlocks and improve performance. Instead, use callbacks or combinators to remain in the future domain:

      val animalRange: Future[Int] = for {
        aardvark <- firstAardvark
        zebra <- firstZebra
      } yield zebra - aardvark

      animalRange.onSuccess {
        case x if x > 500000 => println("It's a long way from Aardvark to Zebra")
      }

  Definition Classes
    scala
-  package duration
  Definition Classes
    concurrent
- Deadline
- DoubleMult
- Duration
- DurationConversions
- DurationDouble
- DurationInt
- DurationLong
- FiniteDuration
- IntMult
- LongMult
- fromNow
- span

t

scala.concurrent.duration

# DurationConversions

###
Companion object DurationConversions

#### trait DurationConversions extends Any

Source
  DurationConversions.scala

Linear Supertypes
Any
Known Subclasses
DurationDouble, DurationInt, DurationLong
Type Hierarchy

Ordering

1. Alphabetic
2. By Inheritance

Inherited

1. DurationConversions
2. 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

### Abstract Value Members

1.  abstract def durationIn(unit: TimeUnit): FiniteDuration
   Attributes
     protected
2.  abstract 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
     Any

### Concrete 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 DurationConversions toany2stringadd[DurationConversions] performed by method any2stringadd in scala.Predef.
   Definition Classes
     any2stringadd
4.  def ->[B](y: B): (DurationConversions, B)
   Implicit
     This member is added by an implicit conversion from DurationConversions toArrowAssoc[DurationConversions] 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

   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.  def day[C](c: C)(implicit ev: Classifier[C]): R
8.  def day: FiniteDuration
9.  def days[C](c: C)(implicit ev: Classifier[C]): R
10.  def days: FiniteDuration
11.  def ensuring(cond: (DurationConversions) => Boolean, msg: => Any): DurationConversions
    Implicit
      This member is added by an implicit conversion from DurationConversions toEnsuring[DurationConversions] performed by method Ensuring in scala.Predef.
    Definition Classes
      Ensuring
12.  def ensuring(cond: (DurationConversions) => Boolean): DurationConversions
    Implicit
      This member is added by an implicit conversion from DurationConversions toEnsuring[DurationConversions] performed by method Ensuring in scala.Predef.
    Definition Classes
      Ensuring
13.  def ensuring(cond: Boolean, msg: => Any): DurationConversions
    Implicit
      This member is added by an implicit conversion from DurationConversions toEnsuring[DurationConversions] performed by method Ensuring in scala.Predef.
    Definition Classes
      Ensuring
14.  def ensuring(cond: Boolean): DurationConversions
    Implicit
      This member is added by an implicit conversion from DurationConversions toEnsuring[DurationConversions] performed by method Ensuring in scala.Predef.
    Definition Classes
      Ensuring
15.  def equals(arg0: Any): Boolean

    Compares the receiver object (`this`) with the argument object (`that`) for equivalence.

    Compares the receiver object (`this`) with the argument object (`that`) for equivalence.

    Any implementation of this method should be an equivalence relation:

    - It is reflexive: for any instance `x` of type `Any`, `x.equals(x)` should return `true`.
    - It is symmetric: for any instances `x` and `y` of type `Any`, `x.equals(y)` should return `true` if and only if `y.equals(x)` returns `true`.
    - It is transitive: for any instances `x`, `y`, and `z` of type `Any` if `x.equals(y)` returns `true` and `y.equals(z)` returns `true`, then `x.equals(z)` should return `true`.

    If you override this method, you should verify that your implementation remains an equivalence relation. Additionally, when overriding this method it is usually necessary to override `hashCode` to ensure that objects which are "equal" (`o1.equals(o2)` returns `true`) hash to the same scala.Int. (`o1.hashCode.equals(o2.hashCode)`).

    returns

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

    Definition Classes
      Any
16.  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 DurationConversions toStringFormat[DurationConversions] performed by method StringFormat in scala.Predef.
    Definition Classes
      StringFormat
    Annotations
      @inline()
17.  def hashCode(): Int

    Calculate a hash code value for the object.

    Calculate a hash code value for the object.

    The default hashing algorithm is platform dependent.

    Note that it is allowed for two objects to have identical hash codes (`o1.hashCode.equals(o2.hashCode)`) yet not be equal (`o1.equals(o2)` returns `false`). A degenerate implementation could always return `0`. However, it is required that if two objects are equal (`o1.equals(o2)` returns `true`) that they have identical hash codes (`o1.hashCode.equals(o2.hashCode)`). Therefore, when overriding this method, be sure to verify that the behavior is consistent with the `equals` method.

    returns

      the hash code value for this object.

    Definition Classes
      Any
18.  def hour[C](c: C)(implicit ev: Classifier[C]): R
19.  def hour: FiniteDuration
20.  def hours[C](c: C)(implicit ev: Classifier[C]): R
21.  def hours: FiniteDuration
22.  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
23.  def micro[C](c: C)(implicit ev: Classifier[C]): R
24.  def micro: FiniteDuration
25.  def micros[C](c: C)(implicit ev: Classifier[C]): R
26.  def micros: FiniteDuration
27.  def microsecond[C](c: C)(implicit ev: Classifier[C]): R
28.  def microsecond: FiniteDuration
29.  def microseconds[C](c: C)(implicit ev: Classifier[C]): R
30.  def microseconds: FiniteDuration
31.  def milli[C](c: C)(implicit ev: Classifier[C]): R
32.  def milli: FiniteDuration
33.  def millis[C](c: C)(implicit ev: Classifier[C]): R
34.  def millis: FiniteDuration
35.  def millisecond[C](c: C)(implicit ev: Classifier[C]): R
36.  def millisecond: FiniteDuration
37.  def milliseconds[C](c: C)(implicit ev: Classifier[C]): R
38.  def milliseconds: FiniteDuration
39.  def minute[C](c: C)(implicit ev: Classifier[C]): R
40.  def minute: FiniteDuration
41.  def minutes[C](c: C)(implicit ev: Classifier[C]): R
42.  def minutes: FiniteDuration
43.  def nano[C](c: C)(implicit ev: Classifier[C]): R
44.  def nano: FiniteDuration
45.  def nanos[C](c: C)(implicit ev: Classifier[C]): R
46.  def nanos: FiniteDuration
47.  def nanosecond[C](c: C)(implicit ev: Classifier[C]): R
48.  def nanosecond: FiniteDuration
49.  def nanoseconds[C](c: C)(implicit ev: Classifier[C]): R
50.  def nanoseconds: FiniteDuration
51.  def second[C](c: C)(implicit ev: Classifier[C]): R
52.  def second: FiniteDuration
53.  def seconds[C](c: C)(implicit ev: Classifier[C]): R
54.  def seconds: FiniteDuration
55.  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](y: B): (DurationConversions, B)
   Implicit
     This member is added by an implicit conversion from DurationConversions toArrowAssoc[DurationConversions] 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 Any

### Inherited by implicit conversion any2stringadd fromDurationConversions to any2stringadd[DurationConversions]

### Inherited by implicit conversion StringFormat fromDurationConversions to StringFormat[DurationConversions]

### Inherited by implicit conversion Ensuring fromDurationConversions to Ensuring[DurationConversions]

### Inherited by implicit conversion ArrowAssoc fromDurationConversions to ArrowAssoc[DurationConversions]

### Ungrouped