SplittableRandom
class SplittableRandom
A generator of uniform pseudorandom values 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 at least 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 System#getProperty java.util.secureRandomSeed is set to true.
Summary
| Public constructors |
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Creates a new SplittableRandom instance using the specified initial seed.
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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.
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| Public methods |
| 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).
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| 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).
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| 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).
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| 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).
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| IntStream! |
Returns a stream producing the given streamSize number of pseudorandom int values from this generator and/or one split from it.
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| IntStream! |
Returns an effectively unlimited stream of pseudorandom int values from this generator and/or one split from it.
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| 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).
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| 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).
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| LongStream! |
Returns a stream producing the given streamSize number of pseudorandom long values from this generator and/or one split from it.
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| LongStream! |
Returns an effectively unlimited stream of pseudorandom long values from this generator and/or one split from it.
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| 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).
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| 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).
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| Boolean |
Returns a pseudorandom boolean value.
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| Double |
Returns a pseudorandom double value between zero (inclusive) and one (exclusive).
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| Double |
Returns a pseudorandom double value between 0.
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| Double |
Returns a pseudorandom double value between the specified origin (inclusive) and bound (exclusive).
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| Int |
Returns a pseudorandom int value.
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| Int |
Returns a pseudorandom int value between zero (inclusive) and the specified bound (exclusive).
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| Int |
Returns a pseudorandom int value between the specified origin (inclusive) and the specified bound (exclusive).
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| Long |
Returns a pseudorandom long value.
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| Long |
Returns a pseudorandom long value between zero (inclusive) and the specified bound (exclusive).
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| Long |
Returns a pseudorandom long value between the specified origin (inclusive) and the specified bound (exclusive).
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| SplittableRandom! |
Constructs and returns a new SplittableRandom instance that shares no mutable state with this instance.
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Public constructors
<init>
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 |
<init>
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
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 |
| Exceptions |
java.lang.IllegalArgumentException |
if streamSize is less than zero |
doubles
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).
doubles
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 randomNumberOrigin is greater than or equal to randomNumberBound |
doubles
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
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
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
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
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
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
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
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
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 |
nextBoolean
fun nextBoolean(): Boolean
Returns a pseudorandom boolean value.
| Return |
Boolean |
a pseudorandom boolean value |
nextDouble
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
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
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 |
nextInt
fun nextInt(): Int
Returns a pseudorandom int value.
| Return |
Int |
a pseudorandom int value |
nextInt
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
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
fun nextLong(): Long
Returns a pseudorandom long value.
| Return |
Long |
a pseudorandom long value |
nextLong
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
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 |
split
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.
