Added in API level 21

ThreadLocalRandom

open class ThreadLocalRandom : Random

kotlin.Any
↳	java.util.Random
	↳	java.util.concurrent.ThreadLocalRandom

A random number generator isolated to the current thread. Like the global java.util.Random generator used by the class, a ThreadLocalRandom is initialized with an internally generated seed that may not otherwise be modified. When applicable, use of ThreadLocalRandom rather than shared Random objects in concurrent programs will typically encounter much less overhead and contention. Use of ThreadLocalRandom is particularly appropriate when multiple tasks (for example, each a ForkJoinTask) use random numbers in parallel in thread pools.

Usages of this class should typically be of the form: ThreadLocalRandom.current().nextX(...) (where X is Int, Long, etc). When all usages are of this form, it is never possible to accidently share a ThreadLocalRandom across multiple threads.

This class also provides additional commonly used bounded random generation methods.

Instances of ThreadLocalRandom are not cryptographically secure. Consider instead using java.security.SecureRandom in security-sensitive applications. Additionally, default-constructed instances do not use a cryptographically random seed unless the java.lang.System#getProperty java.util.secureRandomSeed is set to true.

Summary

Public methods
open static ThreadLocalRandom!	`current()` Returns the current thread's `ThreadLocalRandom`.
open DoubleStream!	`doubles(streamSize: Long)` Returns a stream producing the given `streamSize` number of pseudorandom `double` values, each between zero (inclusive) and one (exclusive).
open DoubleStream!	`doubles()` Returns an effectively unlimited stream of pseudorandom `double` values, each between zero (inclusive) and one (exclusive).
open DoubleStream!	`doubles(streamSize: Long, randomNumberOrigin: Double, randomNumberBound: Double)` Returns a stream producing the given `streamSize` number of pseudorandom `double` values, each conforming to the given origin (inclusive) and bound (exclusive).
open DoubleStream!	`doubles(randomNumberOrigin: Double, randomNumberBound: Double)` Returns an effectively unlimited stream of pseudorandom `double` values, each conforming to the given origin (inclusive) and bound (exclusive).
open IntStream!	`ints(streamSize: Long)` Returns a stream producing the given `streamSize` number of pseudorandom `int` values.
open IntStream!	`ints()` Returns an effectively unlimited stream of pseudorandom `int` values.
open IntStream!	`ints(streamSize: Long, randomNumberOrigin: Int, randomNumberBound: Int)` Returns a stream producing the given `streamSize` number of pseudorandom `int` values, each conforming to the given origin (inclusive) and bound (exclusive).
open IntStream!	`ints(randomNumberOrigin: Int, randomNumberBound: Int)` Returns an effectively unlimited stream of pseudorandom `int` values, each conforming to the given origin (inclusive) and bound (exclusive).
open LongStream!	`longs(streamSize: Long)` Returns a stream producing the given `streamSize` number of pseudorandom `long` values.
open LongStream!	`longs()` Returns an effectively unlimited stream of pseudorandom `long` values.
open LongStream!	`longs(streamSize: Long, randomNumberOrigin: Long, randomNumberBound: Long)` Returns a stream producing the given `streamSize` number of pseudorandom `long`, each conforming to the given origin (inclusive) and bound (exclusive).
open LongStream!	`longs(randomNumberOrigin: Long, randomNumberBound: Long)` Returns an effectively unlimited stream of pseudorandom `long` values, each conforming to the given origin (inclusive) and bound (exclusive).
open Boolean	`nextBoolean()` Returns a pseudorandom `boolean` value.
open Double	`nextDouble()` Returns a pseudorandom `double` value between zero (inclusive) and one (exclusive).
open Double	`nextDouble(bound: Double)` Returns a pseudorandom `double` value between 0.
open Double	`nextDouble(origin: Double, bound: Double)` Returns a pseudorandom `double` value between the specified origin (inclusive) and bound (exclusive).
open Float	`nextFloat()` Returns a pseudorandom `float` value between zero (inclusive) and one (exclusive).
open Double	`nextGaussian()`
open Int	`nextInt()` Returns a pseudorandom `int` value.
open Int	`nextInt(bound: Int)` Returns a pseudorandom `int` value between zero (inclusive) and the specified bound (exclusive).
open Int	`nextInt(origin: Int, bound: Int)` Returns a pseudorandom `int` value between the specified origin (inclusive) and the specified bound (exclusive).
open Long	`nextLong()` Returns a pseudorandom `long` value.
open Long	`nextLong(bound: Long)` Returns a pseudorandom `long` value between zero (inclusive) and the specified bound (exclusive).
open Long	`nextLong(origin: Long, bound: Long)` Returns a pseudorandom `long` value between the specified origin (inclusive) and the specified bound (exclusive).
open Unit	`setSeed(seed: Long)` Throws `UnsupportedOperationException`.

Protected methods
open Int	`next(bits: Int)`

Inherited functions

From class Random

Unit

nextBytes(bytes: ByteArray!)

Generates random bytes and places them into a user-supplied byte array. The number of random bytes produced is equal to the length of the byte array.

The method nextBytes is implemented by class Random as if by:

<code>public void nextBytes(byte[] bytes) {
    for (int i = 0; i &lt; bytes.length; )
      for (int rnd = nextInt(), n = Math.min(bytes.length - i, 4);
           n-- &gt; 0; rnd &gt;&gt;= 8)
        bytes[i++] = (byte)rnd;
  }</code>

Public methods

current

Added in API level 21

open static fun current(): ThreadLocalRandom!

Returns the current thread's ThreadLocalRandom.

Return
`ThreadLocalRandom!`	the current thread's `ThreadLocalRandom`

doubles

Added in API level 24

open fun doubles(streamSize: Long): DoubleStream!

Returns a stream producing the given streamSize number of pseudorandom double values, each between zero (inclusive) and one (exclusive).

Parameters
`streamSize`	Long: the number of values to generate

Return
`DoubleStream!`	a stream of `double` values

Exceptions
`java.lang.IllegalArgumentException`	if `streamSize` is less than zero

doubles

Added in API level 24

open fun doubles(): DoubleStream!

Returns an effectively unlimited stream of pseudorandom double values, each between zero (inclusive) and one (exclusive).

Return
`DoubleStream!`	a stream of pseudorandom `double` values

doubles

Added in API level 24

open fun doubles(
    streamSize: Long, 
    randomNumberOrigin: Double, 
    randomNumberBound: Double
): DoubleStream!

Returns a stream producing the given streamSize number of pseudorandom double values, each conforming to the given origin (inclusive) and bound (exclusive).

Parameters
`streamSize`	Long: the number of values to generate
`randomNumberOrigin`	Double: the origin (inclusive) of each random value
`randomNumberBound`	Double: the bound (exclusive) of each random value

Return
`DoubleStream!`	a stream of pseudorandom `double` values, each with the given origin (inclusive) and bound (exclusive)

Exceptions
`java.lang.IllegalArgumentException`	if `randomNumberOrigin` is greater than or equal to `randomNumberBound`

doubles

Added in API level 24

open fun doubles(
    randomNumberOrigin: Double, 
    randomNumberBound: Double
): DoubleStream!

Returns an effectively unlimited stream of pseudorandom double values, each conforming to the given origin (inclusive) and bound (exclusive).

Parameters
`randomNumberOrigin`	Double: the origin (inclusive) of each random value
`randomNumberBound`	Double: the bound (exclusive) of each random value

Return
`DoubleStream!`	a stream of pseudorandom `double` values, each with the given origin (inclusive) and bound (exclusive)

Exceptions
`java.lang.IllegalArgumentException`	if `randomNumberOrigin` is greater than or equal to `randomNumberBound`

ints

Added in API level 24

open fun ints(streamSize: Long): IntStream!

Returns a stream producing the given streamSize number of pseudorandom int values.

Parameters
`streamSize`	Long: the number of values to generate

Return
`IntStream!`	a stream of pseudorandom `int` values

Exceptions
`java.lang.IllegalArgumentException`	if `streamSize` is less than zero

ints

Added in API level 24

open fun ints(): IntStream!

Returns an effectively unlimited stream of pseudorandom int values.

Return
`IntStream!`	a stream of pseudorandom `int` values

ints

Added in API level 24

open fun ints(
    streamSize: Long, 
    randomNumberOrigin: Int, 
    randomNumberBound: Int
): IntStream!

Returns a stream producing the given streamSize number of pseudorandom int values, each conforming to the given origin (inclusive) and bound (exclusive).

Parameters
`streamSize`	Long: the number of values to generate
`randomNumberOrigin`	Int: the origin (inclusive) of each random value
`randomNumberBound`	Int: the bound (exclusive) of each random value

Return
`IntStream!`	a stream of pseudorandom `int` values, each with the given origin (inclusive) and bound (exclusive)

Exceptions
`java.lang.IllegalArgumentException`	if `streamSize` is less than zero, or `randomNumberOrigin` is greater than or equal to `randomNumberBound`

ints

Added in API level 24

open fun ints(
    randomNumberOrigin: Int, 
    randomNumberBound: Int
): IntStream!

Returns an effectively unlimited stream of pseudorandom int values, each conforming to the given origin (inclusive) and bound (exclusive).

Parameters
`randomNumberOrigin`	Int: the origin (inclusive) of each random value
`randomNumberBound`	Int: the bound (exclusive) of each random value

Return
`IntStream!`	a stream of pseudorandom `int` values, each with the given origin (inclusive) and bound (exclusive)

Exceptions
`java.lang.IllegalArgumentException`	if `randomNumberOrigin` is greater than or equal to `randomNumberBound`

longs

Added in API level 24

open fun longs(streamSize: Long): LongStream!

Returns a stream producing the given streamSize number of pseudorandom long values.

Parameters
`streamSize`	Long: the number of values to generate

Return
`LongStream!`	a stream of pseudorandom `long` values

Exceptions
`java.lang.IllegalArgumentException`	if `streamSize` is less than zero

longs

Added in API level 24

open fun longs(): LongStream!

Returns an effectively unlimited stream of pseudorandom long values.

Return
`LongStream!`	a stream of pseudorandom `long` values

longs

Added in API level 24

open fun longs(
    streamSize: Long, 
    randomNumberOrigin: Long, 
    randomNumberBound: Long
): LongStream!

Returns a stream producing the given streamSize number of pseudorandom long, each conforming to the given origin (inclusive) and bound (exclusive).

Parameters
`streamSize`	Long: the number of values to generate
`randomNumberOrigin`	Long: the origin (inclusive) of each random value
`randomNumberBound`	Long: the bound (exclusive) of each random value

Return
`LongStream!`	a stream of pseudorandom `long` values, each with the given origin (inclusive) and bound (exclusive)

Exceptions
`java.lang.IllegalArgumentException`	if `streamSize` is less than zero, or `randomNumberOrigin` is greater than or equal to `randomNumberBound`

longs

Added in API level 24

open fun longs(
    randomNumberOrigin: Long, 
    randomNumberBound: Long
): LongStream!

Returns an effectively unlimited stream of pseudorandom long values, each conforming to the given origin (inclusive) and bound (exclusive).

Parameters
`randomNumberOrigin`	Long: the origin (inclusive) of each random value
`randomNumberBound`	Long: the bound (exclusive) of each random value

Return
`LongStream!`	a stream of pseudorandom `long` values, each with the given origin (inclusive) and bound (exclusive)

Exceptions
`java.lang.IllegalArgumentException`	if `randomNumberOrigin` is greater than or equal to `randomNumberBound`

nextBoolean

Added in API level 21

open fun nextBoolean(): Boolean

Returns a pseudorandom boolean value.

Return
`Boolean`	a pseudorandom `boolean` value

nextDouble

Added in API level 21

open fun nextDouble(): Double

Returns a pseudorandom double value between zero (inclusive) and one (exclusive).

Return
`Double`	a pseudorandom `double` value between zero (inclusive) and one (exclusive)

nextDouble

Added in API level 21

open fun nextDouble(bound: Double): Double

Returns a pseudorandom double value between 0.0 (inclusive) and the specified bound (exclusive).

Parameters
`bound`	Double: the upper bound (exclusive). Must be positive.

Return
`Double`	a pseudorandom `double` value between zero (inclusive) and the bound (exclusive)

Exceptions
`java.lang.IllegalArgumentException`	if `bound` is not positive

nextDouble

Added in API level 21

open fun nextDouble(
    origin: Double, 
    bound: Double
): Double

Returns a pseudorandom double value between the specified origin (inclusive) and bound (exclusive).

Parameters
`origin`	Double: the least value returned
`bound`	Double: the upper bound (exclusive)

Return
`Double`	a pseudorandom `double` value between the origin (inclusive) and the bound (exclusive)

Exceptions
`java.lang.IllegalArgumentException`	if `origin` is greater than or equal to `bound`

nextFloat

Added in API level 21

open fun nextFloat(): Float

Returns a pseudorandom float value between zero (inclusive) and one (exclusive).

Return
`Float`	a pseudorandom `float` value between zero (inclusive) and one (exclusive)

nextGaussian

Added in API level 21

open fun nextGaussian(): Double

Return
`Double`	the next pseudorandom, Gaussian ("normally") distributed `double` value with mean `0.0` and standard deviation `1.0` from this random number generator's sequence

nextInt

Added in API level 21

open fun nextInt(): Int

Returns a pseudorandom int value.

Return
`Int`	a pseudorandom `int` value

nextInt

Added in API level 21

open fun nextInt(bound: Int): Int

Returns a pseudorandom int value between zero (inclusive) and the specified bound (exclusive).

Parameters
`bound`	Int: the upper bound (exclusive). Must be positive.

Return
`Int`	a pseudorandom `int` value between zero (inclusive) and the bound (exclusive)

Exceptions
`java.lang.IllegalArgumentException`	if `bound` is not positive

nextInt

Added in API level 21

open fun nextInt(
    origin: Int, 
    bound: Int
): Int

Returns a pseudorandom int value between the specified origin (inclusive) and the specified bound (exclusive).

Parameters
`origin`	Int: the least value returned
`bound`	Int: the upper bound (exclusive)

Return
`Int`	a pseudorandom `int` value between the origin (inclusive) and the bound (exclusive)

Exceptions
`java.lang.IllegalArgumentException`	if `origin` is greater than or equal to `bound`

nextLong

Added in API level 21

open fun nextLong(): Long

Returns a pseudorandom long value.

Return
`Long`	a pseudorandom `long` value

nextLong

Added in API level 21

open fun nextLong(bound: Long): Long

Returns a pseudorandom long value between zero (inclusive) and the specified bound (exclusive).

Parameters
`bound`	Long: the upper bound (exclusive). Must be positive.

Return
`Long`	a pseudorandom `long` value between zero (inclusive) and the bound (exclusive)

Exceptions
`java.lang.IllegalArgumentException`	if `bound` is not positive

nextLong

Added in API level 21

open fun nextLong(
    origin: Long, 
    bound: Long
): Long

Returns a pseudorandom long value between the specified origin (inclusive) and the specified bound (exclusive).

Parameters
`origin`	Long: the least value returned
`bound`	Long: the upper bound (exclusive)

Return
`Long`	a pseudorandom `long` value between the origin (inclusive) and the bound (exclusive)

Exceptions
`java.lang.IllegalArgumentException`	if `origin` is greater than or equal to `bound`

setSeed

Added in API level 21

open fun setSeed(seed: Long): Unit

Throws UnsupportedOperationException. Setting seeds in this generator is not supported.

Parameters
`seed`	Long: the initial seed

Exceptions
`java.lang.UnsupportedOperationException`	always

Protected methods

Added in API level 21

protected open fun next(bits: Int): Int

Parameters
`bits`	Int: random bits

Return
`Int`	the next pseudorandom value from this random number generator's sequence