Package Summary  Overview Summary

class:SplittableRandom [NONE]


  • public final class SplittableRandom
    extends Object
    
    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 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 SecureRandom in security-sensitive applications. Additionally, default-constructed instances do not use a cryptographically random seed unless the system property java.util.secureRandomSeed is set to true.

    Since:
    1.8

constructor:<init>(long) [NONE]

  • SplittableRandom

    public SplittableRandom​(long seed)
    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 - the initial seed

constructor:<init>() [NONE]

  • SplittableRandom

    public 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.

method:split() [NONE]

  • split

    public SplittableRandom split()
    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.
    Returns:
    the new SplittableRandom instance

method:nextBytes(byte[]) [NONE]

  • nextBytes

    public void nextBytes​(byte[] bytes)
    Fills a user-supplied byte array with generated pseudorandom bytes.
    Parameters:
    bytes - the byte array to fill with pseudorandom bytes
    Throws:
    NullPointerException - if bytes is null
    Since:
    10

method:nextInt() [NONE]

  • nextInt

    public int nextInt()
    Returns a pseudorandom int value.
    Returns:
    a pseudorandom int value

method:nextInt(int) [NONE]

  • nextInt

    public int nextInt​(int bound)
    Returns a pseudorandom int value between zero (inclusive) and the specified bound (exclusive).
    Parameters:
    bound - the upper bound (exclusive). Must be positive.
    Returns:
    a pseudorandom int value between zero (inclusive) and the bound (exclusive)
    Throws:
    IllegalArgumentException - if bound is not positive

method:nextInt(int,int) [NONE]

  • nextInt

    public int nextInt​(int origin,
                       int bound)
    Returns a pseudorandom int value between the specified origin (inclusive) and the specified bound (exclusive).
    Parameters:
    origin - the least value returned
    bound - the upper bound (exclusive)
    Returns:
    a pseudorandom int value between the origin (inclusive) and the bound (exclusive)
    Throws:
    IllegalArgumentException - if origin is greater than or equal to bound

method:nextLong() [NONE]

  • nextLong

    public long nextLong()
    Returns a pseudorandom long value.
    Returns:
    a pseudorandom long value

method:nextLong(long) [NONE]

  • nextLong

    public long nextLong​(long bound)
    Returns a pseudorandom long value between zero (inclusive) and the specified bound (exclusive).
    Parameters:
    bound - the upper bound (exclusive). Must be positive.
    Returns:
    a pseudorandom long value between zero (inclusive) and the bound (exclusive)
    Throws:
    IllegalArgumentException - if bound is not positive

method:nextLong(long,long) [NONE]

  • nextLong

    public long nextLong​(long origin,
                         long bound)
    Returns a pseudorandom long value between the specified origin (inclusive) and the specified bound (exclusive).
    Parameters:
    origin - the least value returned
    bound - the upper bound (exclusive)
    Returns:
    a pseudorandom long value between the origin (inclusive) and the bound (exclusive)
    Throws:
    IllegalArgumentException - if origin is greater than or equal to bound

method:nextDouble() [NONE]

  • nextDouble

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

method:nextDouble(double) [NONE]

  • nextDouble

    public double nextDouble​(double bound)
    Returns a pseudorandom double value between 0.0 (inclusive) and the specified bound (exclusive).
    Parameters:
    bound - the upper bound (exclusive). Must be positive.
    Returns:
    a pseudorandom double value between zero (inclusive) and the bound (exclusive)
    Throws:
    IllegalArgumentException - if bound is not positive

method:nextDouble(double,double) [NONE]

  • nextDouble

    public double nextDouble​(double origin,
                             double bound)
    Returns a pseudorandom double value between the specified origin (inclusive) and bound (exclusive).
    Parameters:
    origin - the least value returned
    bound - the upper bound (exclusive)
    Returns:
    a pseudorandom double value between the origin (inclusive) and the bound (exclusive)
    Throws:
    IllegalArgumentException - if origin is greater than or equal to bound

method:nextBoolean() [NONE]

  • nextBoolean

    public boolean nextBoolean()
    Returns a pseudorandom boolean value.
    Returns:
    a pseudorandom boolean value

method:ints(long) [NONE]

  • ints

    public IntStream ints​(long streamSize)
    Returns a stream producing the given streamSize number of pseudorandom int values from this generator and/or one split from it.
    Parameters:
    streamSize - the number of values to generate
    Returns:
    a stream of pseudorandom int values
    Throws:
    IllegalArgumentException - if streamSize is less than zero

method:ints() [NONE]

  • ints

    public IntStream ints()
    Returns an effectively unlimited stream of pseudorandom int values from this generator and/or one split from it.
    Implementation Note:
    This method is implemented to be equivalent to ints(Long.MAX_VALUE) .
    Returns:
    a stream of pseudorandom int values

method:ints(long,int,int) [NONE]

  • ints

    public IntStream ints​(long streamSize,
                          int randomNumberOrigin,
                          int randomNumberBound)
    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 - the number of values to generate
    randomNumberOrigin - the origin (inclusive) of each random value
    randomNumberBound - the bound (exclusive) of each random value
    Returns:
    a stream of pseudorandom int values, each with the given origin (inclusive) and bound (exclusive)
    Throws:
    IllegalArgumentException - if streamSize is less than zero, or randomNumberOrigin is greater than or equal to randomNumberBound

method:ints(int,int) [NONE]

  • ints

    public IntStream ints​(int randomNumberOrigin,
                          int randomNumberBound)
    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).
    Implementation Note:
    This method is implemented to be equivalent to ints(Long.MAX_VALUE, randomNumberOrigin, randomNumberBound) .
    Parameters:
    randomNumberOrigin - the origin (inclusive) of each random value
    randomNumberBound - the bound (exclusive) of each random value
    Returns:
    a stream of pseudorandom int values, each with the given origin (inclusive) and bound (exclusive)
    Throws:
    IllegalArgumentException - if randomNumberOrigin is greater than or equal to randomNumberBound

method:longs(long) [NONE]

  • longs

    public LongStream longs​(long streamSize)
    Returns a stream producing the given streamSize number of pseudorandom long values from this generator and/or one split from it.
    Parameters:
    streamSize - the number of values to generate
    Returns:
    a stream of pseudorandom long values
    Throws:
    IllegalArgumentException - if streamSize is less than zero

method:longs() [NONE]

  • longs

    public LongStream longs()
    Returns an effectively unlimited stream of pseudorandom long values from this generator and/or one split from it.
    Implementation Note:
    This method is implemented to be equivalent to longs(Long.MAX_VALUE) .
    Returns:
    a stream of pseudorandom long values

method:longs(long,long,long) [NONE]

  • longs

    public LongStream longs​(long streamSize,
                            long randomNumberOrigin,
                            long randomNumberBound)
    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 - the number of values to generate
    randomNumberOrigin - the origin (inclusive) of each random value
    randomNumberBound - the bound (exclusive) of each random value
    Returns:
    a stream of pseudorandom long values, each with the given origin (inclusive) and bound (exclusive)
    Throws:
    IllegalArgumentException - if streamSize is less than zero, or randomNumberOrigin is greater than or equal to randomNumberBound

method:longs(long,long) [NONE]

  • longs

    public LongStream longs​(long randomNumberOrigin,
                            long randomNumberBound)
    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).
    Implementation Note:
    This method is implemented to be equivalent to longs(Long.MAX_VALUE, randomNumberOrigin, randomNumberBound) .
    Parameters:
    randomNumberOrigin - the origin (inclusive) of each random value
    randomNumberBound - the bound (exclusive) of each random value
    Returns:
    a stream of pseudorandom long values, each with the given origin (inclusive) and bound (exclusive)
    Throws:
    IllegalArgumentException - if randomNumberOrigin is greater than or equal to randomNumberBound

method:doubles(long) [NONE]

  • doubles

    public DoubleStream doubles​(long streamSize)
    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 - the number of values to generate
    Returns:
    a stream of double values
    Throws:
    IllegalArgumentException - if streamSize is less than zero

method:doubles() [NONE]

  • doubles

    public DoubleStream doubles()
    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).
    Implementation Note:
    This method is implemented to be equivalent to doubles(Long.MAX_VALUE) .
    Returns:
    a stream of pseudorandom double values

method:doubles(long,double,double) [NONE]

  • doubles

    public DoubleStream doubles​(long streamSize,
                                double randomNumberOrigin,
                                double randomNumberBound)
    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 - the number of values to generate
    randomNumberOrigin - the origin (inclusive) of each random value
    randomNumberBound - the bound (exclusive) of each random value
    Returns:
    a stream of pseudorandom double values, each with the given origin (inclusive) and bound (exclusive)
    Throws:
    IllegalArgumentException - if streamSize is less than zero, or randomNumberOrigin is greater than or equal to randomNumberBound

method:doubles(double,double) [NONE]

  • doubles

    public DoubleStream doubles​(double randomNumberOrigin,
                                double randomNumberBound)
    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).
    Implementation Note:
    This method is implemented to be equivalent to doubles(Long.MAX_VALUE, randomNumberOrigin, randomNumberBound) .
    Parameters:
    randomNumberOrigin - the origin (inclusive) of each random value
    randomNumberBound - the bound (exclusive) of each random value
    Returns:
    a stream of pseudorandom double values, each with the given origin (inclusive) and bound (exclusive)
    Throws:
    IllegalArgumentException - if randomNumberOrigin is greater than or equal to randomNumberBound

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