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:

    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 Futures, 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 source = scala.io.Source.fromFile("/etc/dictionaries-common/words")
  source.toSeq.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

sealed abstract class Duration extends Serializable with Ordered[Duration]

Utility for working with java.util.concurrent.TimeUnit durations.

This class is not meant as a general purpose representation of time, it is optimized for the needs of scala.concurrent.

Basic Usage

Examples:

import scala.concurrent.duration._

val duration = Duration(100, MILLISECONDS)
val duration = Duration(100, "millis")

duration.toNanos
duration < 1.second
duration <= Duration.Inf

Invoking inexpressible conversions (like calling toSeconds on an infinite duration) will throw an IllegalArgumentException.

Implicits are also provided for Int, Long and Double. Example usage:

import scala.concurrent.duration._

val duration = 100.millis

The DSL provided by the implicit conversions always allows construction of finite durations, even for infinite Double inputs; use Duration.Inf instead.

Extractors, parsing and arithmetic are also included:

val d = Duration("1.2 µs")
val Duration(length, unit) = 5 millis
val d2 = d * 2.5
val d3 = d2 + 1.millisecond

Handling of Time Units

Calculations performed on finite durations always retain the more precise unit of either operand, no matter whether a coarser unit would be able to exactly express the same duration. This means that Duration can be used as a lossless container for a (length, unit) pair if it is constructed using the corresponding methods and no arithmetic is performed on it; adding/subtracting durations should in that case be done with care.

Correspondence to Double Semantics

The semantics of arithmetic operations on Duration are two-fold:

  • exact addition/subtraction with nanosecond resolution for finite durations, independent of the summands' magnitude
  • isomorphic to java.lang.Double when it comes to infinite or undefined values

The conversion between Duration and Double is done using Duration.toUnit (with unit NANOSECONDS) and Duration.fromNanos(Double)

Ordering

The default ordering is consistent with the ordering of Double numbers, which means that Undefined is considered greater than all other durations, including Duration.Inf.

Source
Duration.scala
Linear Supertypes
math.Ordered[Duration], Comparable[Duration], java.io.Serializable, AnyRef, Any
Known Subclasses
Infinite, FiniteDuration
Type Hierarchy
Ordering
  1. Alphabetic
  2. By Inheritance
Inherited
  1. Duration
  2. Ordered
  3. Comparable
  4. Serializable
  5. AnyRef
  6. Any
Implicitly
  1. by orderingToOrdered
  2. by durationToPair
  3. by any2stringadd
  4. by StringFormat
  5. by Ensuring
  6. by ArrowAssoc
  1. Hide All
  2. Show All
Visibility
  1. Public
  2. All

Abstract Value Members

  1. abstract def *(factor: Double): Duration

    Return this duration multiplied by the scalar factor.

    Return this duration multiplied by the scalar factor. When involving non-finite factors the semantics match those of Double.

    Exceptions thrown

    IllegalArgumentException in case of a finite overflow: the range of a finite duration is +-(2^63-1)ns, and no conversion to infinite durations takes place.

  2. abstract def +(other: Duration): Duration

    Return the sum of that duration and this.

    Return the sum of that duration and this. When involving non-finite summands the semantics match those of Double.

    Exceptions thrown

    IllegalArgumentException in case of a finite overflow: the range of a finite duration is +-(2^63-1)ns, and no conversion to infinite durations takes place.

  3. abstract def -(other: Duration): Duration

    Return the difference of that duration and this.

    Return the difference of that duration and this. When involving non-finite summands the semantics match those of Double.

    Exceptions thrown

    IllegalArgumentException in case of a finite overflow: the range of a finite duration is +-(2^63-1)ns, and no conversion to infinite durations takes place.

  4. abstract def /(divisor: Duration): Double

    Return the quotient of this and that duration as floating-point number.

    Return the quotient of this and that duration as floating-point number. The semantics are determined by Double as if calculating the quotient of the nanosecond lengths of both factors.

  5. abstract def /(divisor: Double): Duration

    Return this duration divided by the scalar factor.

    Return this duration divided by the scalar factor. When involving non-finite factors the semantics match those of Double.

    Exceptions thrown

    IllegalArgumentException in case of a finite overflow: the range of a finite duration is +-(2^63-1)ns, and no conversion to infinite durations takes place.

  6. abstract def compare(that: Duration): Int

    Result of comparing this with operand that.

    Result of comparing this with operand that.

    Implement this method to determine how instances of A will be sorted.

    Returns x where:

    • x < 0 when this < that
    • x == 0 when this == that
    • x > 0 when this > that
    Definition Classes
    Ordered
  7. abstract def isFinite: Boolean

    This method returns whether this duration is finite, which is not the same as !isInfinite for Double because this method also returns false for Duration.Undefined.

  8. abstract def length: Long

    Obtain the length of this Duration measured in the unit obtained by the unit method.

    Obtain the length of this Duration measured in the unit obtained by the unit method.

    Exceptions thrown

    IllegalArgumentException when invoked on a non-finite duration

  9. abstract def toCoarsest: Duration

    Return duration which is equal to this duration but with a coarsest Unit, or self in case it is already the coarsest Unit

    Return duration which is equal to this duration but with a coarsest Unit, or self in case it is already the coarsest Unit

    Examples:

    Duration(60, MINUTES).toCoarsest // Duration(1, HOURS)
Duration(1000, MILLISECONDS).toCoarsest // Duration(1, SECONDS)
Duration(48, HOURS).toCoarsest // Duration(2, DAYS)
Duration(5, SECONDS).toCoarsest // Duration(5, SECONDS)
  10. abstract def toDays: Long

    Return the length of this duration measured in whole days, rounding towards zero.

    Return the length of this duration measured in whole days, rounding towards zero.

    Exceptions thrown

    IllegalArgumentException when invoked on a non-finite duration

  11. abstract def toHours: Long

    Return the length of this duration measured in whole hours, rounding towards zero.

    Return the length of this duration measured in whole hours, rounding towards zero.

    Exceptions thrown

    IllegalArgumentException when invoked on a non-finite duration

  12. abstract def toMicros: Long

    Return the length of this duration measured in whole microseconds, rounding towards zero.

    Return the length of this duration measured in whole microseconds, rounding towards zero.

    Exceptions thrown

    IllegalArgumentException when invoked on a non-finite duration

  13. abstract def toMillis: Long

    Return the length of this duration measured in whole milliseconds, rounding towards zero.

    Return the length of this duration measured in whole milliseconds, rounding towards zero.

    Exceptions thrown

    IllegalArgumentException when invoked on a non-finite duration

  14. abstract def toMinutes: Long

    Return the length of this duration measured in whole minutes, rounding towards zero.

    Return the length of this duration measured in whole minutes, rounding towards zero.

    Exceptions thrown

    IllegalArgumentException when invoked on a non-finite duration

  15. abstract def toNanos: Long

    Return the length of this duration measured in whole nanoseconds, rounding towards zero.

    Return the length of this duration measured in whole nanoseconds, rounding towards zero.

    Exceptions thrown

    IllegalArgumentException when invoked on a non-finite duration

  16. abstract def toSeconds: Long

    Return the length of this duration measured in whole seconds, rounding towards zero.

    Return the length of this duration measured in whole seconds, rounding towards zero.

    Exceptions thrown

    IllegalArgumentException when invoked on a non-finite duration

  17. abstract def toUnit(unit: TimeUnit): Double

    Return the number of nanoseconds as floating point number, scaled down to the given unit.

    Return the number of nanoseconds as floating point number, scaled down to the given unit. The result may not precisely represent this duration due to the Double datatype's inherent limitations (mantissa size effectively 53 bits). Non-finite durations are represented as

  18. abstract def unary_-: Duration

    Negate this duration.

    Negate this duration. The only two values which are mapped to themselves are Duration.Zero and Duration.Undefined.

  19. abstract def unit: TimeUnit

    Obtain the time unit in which the length of this duration is measured.

    Obtain the time unit in which the length of this duration is measured.

    Exceptions thrown

    IllegalArgumentException when invoked on a non-finite duration

Concrete Value Members

  1. def <(that: Duration): Boolean

    Returns true if this is less than that

    Returns true if this is less than that

    Definition Classes
    Ordered
  2. def <=(that: Duration): Boolean

    Returns true if this is less than or equal to that.

    Returns true if this is less than or equal to that.

    Definition Classes
    Ordered
  3. def >(that: Duration): Boolean

    Returns true if this is greater than that.

    Returns true if this is greater than that.

    Definition Classes
    Ordered
  4. def >=(that: Duration): Boolean

    Returns true if this is greater than or equal to that.

    Returns true if this is greater than or equal to that.

    Definition Classes
    Ordered
  5. def compareTo(that: Duration): Int

    Result of comparing this with operand that.

    Result of comparing this with operand that.

    Definition Classes
    Ordered → Comparable
  6. def div(other: Duration): Double

    Return the quotient of this and that duration as floating-point number.

    Return the quotient of this and that duration as floating-point number. The semantics are determined by Double as if calculating the quotient of the nanosecond lengths of both factors.

  7. def div(divisor: Double): Duration

    Return this duration divided by the scalar factor.

    Return this duration divided by the scalar factor. When involving non-finite factors the semantics match those of Double.

    Exceptions thrown

    IllegalArgumentException in case of a finite overflow: the range of a finite duration is +-(2^63-1)ns, and no conversion to infinite durations takes place.

  8. def gt(other: Duration): Boolean
  9. def gteq(other: Duration): Boolean
  10. def lt(other: Duration): Boolean
  11. def lteq(other: Duration): Boolean
  12. def max(other: Duration): Duration

    Return the larger of this and that duration as determined by the natural ordering.

  13. def min(other: Duration): Duration

    Return the smaller of this and that duration as determined by the natural ordering.

  14. def minus(other: Duration): Duration

    Return the difference of that duration and this.

    Return the difference of that duration and this. When involving non-finite summands the semantics match those of Double.

    Exceptions thrown

    IllegalArgumentException in case of a finite overflow: the range of a finite duration is +-(2^63-1)ns, and no conversion to infinite durations takes place.

  15. def mul(factor: Double): Duration

    Return this duration multiplied by the scalar factor.

    Return this duration multiplied by the scalar factor. When involving non-finite factors the semantics match those of Double.

    Exceptions thrown

    IllegalArgumentException in case of a finite overflow: the range of a finite duration is +-(2^63-1)ns, and no conversion to infinite durations takes place.

  16. def neg(): Duration

    Negate this duration.

    Negate this duration. The only two values which are mapped to themselves are Duration.Zero and Duration.Undefined.

  17. def plus(other: Duration): Duration

    Return the sum of that duration and this.

    Return the sum of that duration and this. When involving non-finite summands the semantics match those of Double.

    Exceptions thrown

    IllegalArgumentException in case of a finite overflow: the range of a finite duration is +-(2^63-1)ns, and no conversion to infinite durations takes place.

  18. def productArity: Int

    The arity of this product.

    The arity of this product.

    returns

    2

    Implicit
    This member is added by an implicit conversion from Duration to(Long, TimeUnit) performed by method durationToPair in scala.concurrent.duration.
    Definition Classes
    Product2 → Product
  19. def productElement(n: Int): Any

    Returns the n-th projection of this product if 0 <= n < productArity, otherwise throws an IndexOutOfBoundsException.

    Returns the n-th projection of this product if 0 <= n < productArity, otherwise throws an IndexOutOfBoundsException.

    n

    number of the projection to be returned

    returns

    same as ._(n+1), for example productElement(0) is the same as ._1.

    Implicit
    This member is added by an implicit conversion from Duration to(Long, TimeUnit) performed by method durationToPair in scala.concurrent.duration.
    Definition Classes
    Product2 → Product
    Annotations
    @throws(classOf[IndexOutOfBoundsException])
    Exceptions thrown

    IndexOutOfBoundsException if the n is out of range(n < 0 || n >= 2).

  20. def productElementNames: Iterator[String]

    An iterator over the names of all the elements of this product.

    An iterator over the names of all the elements of this product.

    Implicit
    This member is added by an implicit conversion from Duration to(Long, TimeUnit) performed by method durationToPair in scala.concurrent.duration.
    Definition Classes
    Product
  21. def swap: (TimeUnit, Long)

    Swaps the elements of this Tuple.

    Swaps the elements of this Tuple.

    returns

    a new Tuple where the first element is the second element of this Tuple and the second element is the first element of this Tuple.

    Implicit
    This member is added by an implicit conversion from Duration to(Long, TimeUnit) performed by method durationToPair in scala.concurrent.duration.
    Definition Classes
    Tuple2

Shadowed Implicit Value Members

  1. def <(that: Duration): Boolean

    Returns true if this is less than that

    Returns true if this is less than that

    Implicit
    This member is added by an implicit conversion from Duration tomath.Ordered[Duration] performed by method orderingToOrdered in scala.math.Ordered.
    Shadowing
    This implicitly inherited member is shadowed by one or more members in this class.
    To access this member you can use a type ascription:
    (duration: math.Ordered[Duration]).<(that)
    Definition Classes
    Ordered
  2. def <=(that: Duration): Boolean

    Returns true if this is less than or equal to that.

    Returns true if this is less than or equal to that.

    Implicit
    This member is added by an implicit conversion from Duration tomath.Ordered[Duration] performed by method orderingToOrdered in scala.math.Ordered.
    Shadowing
    This implicitly inherited member is shadowed by one or more members in this class.
    To access this member you can use a type ascription:
    (duration: math.Ordered[Duration]).<=(that)
    Definition Classes
    Ordered
  3. def >(that: Duration): Boolean

    Returns true if this is greater than that.

    Returns true if this is greater than that.

    Implicit
    This member is added by an implicit conversion from Duration tomath.Ordered[Duration] performed by method orderingToOrdered in scala.math.Ordered.
    Shadowing
    This implicitly inherited member is shadowed by one or more members in this class.
    To access this member you can use a type ascription:
    (duration: math.Ordered[Duration]).>(that)
    Definition Classes
    Ordered
  4. def >=(that: Duration): Boolean

    Returns true if this is greater than or equal to that.

    Returns true if this is greater than or equal to that.

    Implicit
    This member is added by an implicit conversion from Duration tomath.Ordered[Duration] performed by method orderingToOrdered in scala.math.Ordered.
    Shadowing
    This implicitly inherited member is shadowed by one or more members in this class.
    To access this member you can use a type ascription:
    (duration: math.Ordered[Duration]).>=(that)
    Definition Classes
    Ordered
  5. def compare(that: Duration): Int

    Result of comparing this with operand that.

    Result of comparing this with operand that.

    Implement this method to determine how instances of A will be sorted.

    Returns x where:

    • x < 0 when this < that
    • x == 0 when this == that
    • x > 0 when this > that
    Implicit
    This member is added by an implicit conversion from Duration tomath.Ordered[Duration] performed by method orderingToOrdered in scala.math.Ordered.
    Shadowing
    This implicitly inherited member is shadowed by one or more members in this class.
    To access this member you can use a type ascription:
    (duration: math.Ordered[Duration]).compare(that)
    Definition Classes
    Ordered
  6. def compareTo(that: Duration): Int

    Result of comparing this with operand that.

    Result of comparing this with operand that.

    Implicit
    This member is added by an implicit conversion from Duration tomath.Ordered[Duration] performed by method orderingToOrdered in scala.math.Ordered.
    Shadowing
    This implicitly inherited member is shadowed by one or more members in this class.
    To access this member you can use a type ascription:
    (duration: math.Ordered[Duration]).compareTo(that)
    Definition Classes
    Ordered → Comparable
  7. 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.

    Implicit
    This member is added by an implicit conversion from Duration to(Long, TimeUnit) performed by method durationToPair in scala.concurrent.duration.
    Shadowing
    This implicitly inherited member is shadowed by one or more members in this class.
    To access this member you can use a type ascription:
    (duration: (Long, TimeUnit)).toString()
    Definition Classes
    Tuple2 → AnyRef → Any