Added in API level 24

SplittableRandom

class SplittableRandom : RandomGenerator, RandomGenerator.SplittableGenerator
kotlin.Any
   ↳ java.util.SplittableRandom

A generator of uniform pseudorandom values (with period 264) applicable for use in (among other contexts) isolated parallel computations that may generate subtasks. Class SplittableRandom supports methods for producing pseudorandom numbers of type int, long, and double with similar usages as for class java.util.Random but differs in the following ways:

  • Series of generated values pass the DieHarder suite testing independence and uniformity properties of random number generators. (Most recently validated with version 3.31.1.) These tests validate only the methods for certain types and ranges, but similar properties are expected to hold, at least approximately, for others as well. The period (length of any series of generated values before it repeats) is 264.
  • Method #split constructs and returns a new SplittableRandom instance that shares no mutable state with the current instance. However, with very high probability, the values collectively generated by the two objects have the same statistical properties as if the same quantity of values were generated by a single thread using a single SplittableRandom object.
  • Instances of SplittableRandom are not thread-safe. They are designed to be split, not shared, across threads. For example, a fork/join-style computation using random numbers might include a construction of the form new Subtask(aSplittableRandom.split()).fork().
  • This class provides additional methods for generating random streams, that employ the above techniques when used in stream.parallel() mode.

Instances of SplittableRandom 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 constructors

Creates a new SplittableRandom instance using the specified initial seed.

Creates a new SplittableRandom instance that is likely to generate sequences of values that are statistically independent of those of any other instances in the current program; and may, and typically does, vary across program invocations.

Public methods
DoubleStream!
doubles(streamSize: Long)

Returns a stream producing the given streamSize number of pseudorandom double values from this generator and/or one split from it; each value is between zero (inclusive) and one (exclusive).

DoubleStream!

Returns an effectively unlimited stream of pseudorandom double values from this generator and/or one split from it; each value is between zero (inclusive) and one (exclusive).

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

Returns a stream producing the given streamSize number of pseudorandom double values from this generator and/or one split from it; each value conforms to the given origin (inclusive) and bound (exclusive).

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

Returns an effectively unlimited stream of pseudorandom double values from this generator and/or one split from it; each value conforms to the given origin (inclusive) and bound (exclusive).

IntStream!
ints(streamSize: Long)

Returns a stream producing the given streamSize number of pseudorandom int values from this generator and/or one split from it.

IntStream!

Returns an effectively unlimited stream of pseudorandom int values from this generator and/or one split from it.

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

Returns a stream producing the given streamSize number of pseudorandom int values from this generator and/or one split from it; each value conforms to the given origin (inclusive) and bound (exclusive).

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

Returns an effectively unlimited stream of pseudorandom int values from this generator and/or one split from it; each value conforms to the given origin (inclusive) and bound (exclusive).

LongStream!
longs(streamSize: Long)

Returns a stream producing the given streamSize number of pseudorandom long values from this generator and/or one split from it.

LongStream!

Returns an effectively unlimited stream of pseudorandom long values from this generator and/or one split from it.

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

Returns a stream producing the given streamSize number of pseudorandom long values from this generator and/or one split from it; each value conforms to the given origin (inclusive) and bound (exclusive).

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

Returns an effectively unlimited stream of pseudorandom long values from this generator and/or one split from it; each value conforms to the given origin (inclusive) and bound (exclusive).

Unit

Fills a user-supplied byte array with generated byte values pseudorandomly chosen uniformly from the range of values between -128 (inclusive) and 127 (inclusive).

Int

Long

SplittableRandom!

Constructs and returns a new SplittableRandom instance that shares no mutable state with this instance.

SplittableRandom!

Returns a new pseudorandom number generator, split off from this one, that implements the RandomGenerator and SplittableGenerator interfaces.

Stream<RandomGenerator.SplittableGenerator!>!

Returns an effectively unlimited stream of new pseudorandom number generators, each of which implements the SplittableGenerator interface.

Stream<RandomGenerator.SplittableGenerator!>!
splits(streamSize: Long)

Returns a stream producing the given streamSize number of new pseudorandom number generators, each of which implements the SplittableGenerator interface.

Stream<RandomGenerator.SplittableGenerator!>!

Returns an effectively unlimited stream of new pseudorandom number generators, each of which implements the SplittableGenerator interface.

Stream<RandomGenerator.SplittableGenerator!>!

Returns a stream producing the given streamSize number of new pseudorandom number generators, each of which implements the SplittableGenerator interface.

Inherited functions

Public constructors

SplittableRandom

Added in API level 24
SplittableRandom(seed: Long)

Creates a new SplittableRandom instance using the specified initial seed. SplittableRandom instances created with the same seed in the same program generate identical sequences of values.

Parameters
seed Long: the initial seed

SplittableRandom

Added in API level 24
SplittableRandom()

Creates a new SplittableRandom instance that is likely to generate sequences of values that are statistically independent of those of any other instances in the current program; and may, and typically does, vary across program invocations.

Public methods

doubles

Added in API level 24
fun doubles(streamSize: Long): DoubleStream!

Returns a stream producing the given streamSize number of pseudorandom double values from this generator and/or one split from it; each value is 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
fun doubles(): DoubleStream!

Returns an effectively unlimited stream of pseudorandom double values from this generator and/or one split from it; each value is between zero (inclusive) and one (exclusive).

Return
DoubleStream! a stream of pseudorandom double values

doubles

Added in API level 24
fun doubles(
    streamSize: Long,
    randomNumberOrigin: Double,
    randomNumberBound: Double
): DoubleStream!

Returns a stream producing the given streamSize number of pseudorandom double values from this generator and/or one split from it; each value conforms 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 streamSize is less than zero, or randomNumberOrigin is greater than or equal to randomNumberBound

doubles

Added in API level 24
fun doubles(
    randomNumberOrigin: Double,
    randomNumberBound: Double
): DoubleStream!

Returns an effectively unlimited stream of pseudorandom double values from this generator and/or one split from it; each value conforms 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
fun ints(streamSize: Long): IntStream!

Returns a stream producing the given streamSize number of pseudorandom int values from this generator and/or one split from it.

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
fun ints(): IntStream!

Returns an effectively unlimited stream of pseudorandom int values from this generator and/or one split from it.

Return
IntStream! a stream of pseudorandom int values

ints

Added in API level 24
fun ints(
    streamSize: Long,
    randomNumberOrigin: Int,
    randomNumberBound: Int
): IntStream!

Returns a stream producing the given streamSize number of pseudorandom int values from this generator and/or one split from it; each value conforms 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
fun ints(
    randomNumberOrigin: Int,
    randomNumberBound: Int
): IntStream!

Returns an effectively unlimited stream of pseudorandom int values from this generator and/or one split from it; each value conforms 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
fun longs(streamSize: Long): LongStream!

Returns a stream producing the given streamSize number of pseudorandom long values from this generator and/or one split from it.

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
fun longs(): LongStream!

Returns an effectively unlimited stream of pseudorandom long values from this generator and/or one split from it.

Return
LongStream! a stream of pseudorandom long values

longs

Added in API level 24
fun longs(
    streamSize: Long,
    randomNumberOrigin: Long,
    randomNumberBound: Long
): LongStream!

Returns a stream producing the given streamSize number of pseudorandom long values from this generator and/or one split from it; each value conforms 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
fun longs(
    randomNumberOrigin: Long,
    randomNumberBound: Long
): LongStream!

Returns an effectively unlimited stream of pseudorandom long values from this generator and/or one split from it; each value conforms 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

nextBytes

Added in API level 33
fun nextBytes(bytes: ByteArray!): Unit

Fills a user-supplied byte array with generated byte values pseudorandomly chosen uniformly from the range of values between -128 (inclusive) and 127 (inclusive).

Parameters
bytes ByteArray!: the byte array to fill with pseudorandom bytes
Exceptions
java.lang.NullPointerException if bytes is null

nextInt

Added in API level 24
fun nextInt(): Int
Return
Int a pseudorandomly chosen int value

nextLong

Added in API level 24
fun nextLong(): Long
Return
Long a pseudorandomly chosen long value

split

Added in API level 24
fun split(): SplittableRandom!

Constructs and returns a new SplittableRandom instance that shares no mutable state with this instance. However, with very high probability, the set of values collectively generated by the two objects has the same statistical properties as if the same quantity of values were generated by a single thread using a single SplittableRandom object. Either or both of the two objects may be further split using the split() method, and the same expected statistical properties apply to the entire set of generators constructed by such recursive splitting.

Return
SplittableRandom! the new SplittableRandom instance

split

fun split(source: RandomGenerator.SplittableGenerator!): SplittableRandom!

Returns a new pseudorandom number generator, split off from this one, that implements the RandomGenerator and SplittableGenerator interfaces.

Parameters
source RandomGenerator.SplittableGenerator!: a SplittableGenerator instance to be used instead of this one as a source of pseudorandom bits used to initialize the state of the new ones.
Return
SplittableRandom! an object that implements the RandomGenerator and SplittableGenerator interfaces
Exceptions
java.lang.NullPointerException if source is null

splits

fun splits(): Stream<RandomGenerator.SplittableGenerator!>!

Returns an effectively unlimited stream of new pseudorandom number generators, each of which implements the SplittableGenerator interface.

This pseudorandom number generator may be used as a source of pseudorandom bits used to initialize the state the new ones.

Return
Stream<RandomGenerator.SplittableGenerator!>! a stream of SplittableGenerator objects

splits

fun splits(streamSize: Long): Stream<RandomGenerator.SplittableGenerator!>!

Returns a stream producing the given streamSize number of new pseudorandom number generators, each of which implements the SplittableGenerator interface.

This pseudorandom number generator may be used as a source of pseudorandom bits used to initialize the state the new ones.

Parameters
streamSize Long: the number of values to generate
Return
Stream<RandomGenerator.SplittableGenerator!>! a stream of SplittableGenerator objects
Exceptions
java.lang.IllegalArgumentException if streamSize is less than zero

splits

fun splits(source: RandomGenerator.SplittableGenerator!): Stream<RandomGenerator.SplittableGenerator!>!

Returns an effectively unlimited stream of new pseudorandom number generators, each of which implements the SplittableGenerator interface.

Parameters
source RandomGenerator.SplittableGenerator!: a SplittableGenerator instance to be used instead of this one as a source of pseudorandom bits used to initialize the state of the new ones.
Return
Stream<RandomGenerator.SplittableGenerator!>! a stream of SplittableGenerator objects
Exceptions
java.lang.NullPointerException if source is null

splits

fun splits(
    streamSize: Long,
    source: RandomGenerator.SplittableGenerator!
): Stream<RandomGenerator.SplittableGenerator!>!

Returns a stream producing the given streamSize number of new pseudorandom number generators, each of which implements the SplittableGenerator interface.

Parameters
streamSize Long: the number of values to generate
source RandomGenerator.SplittableGenerator!: a SplittableGenerator instance to be used instead of this one as a source of pseudorandom bits used to initialize the state of the new ones.
Return
Stream<RandomGenerator.SplittableGenerator!>! a stream of SplittableGenerator objects
Exceptions
java.lang.IllegalArgumentException if streamSize is less than zero
java.lang.NullPointerException if source is null