Package io.netty.util.internal

Class ThreadLocalRandom

java.lang.Object
java.util.Random
io.netty.util.internal.ThreadLocalRandom
All Implemented Interfaces:
Serializable, java.util.random.RandomGenerator
public final class ThreadLocalRandom extends Random
A random number generator isolated to the current thread. Like the global Random generator used by the Math 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
invalid reference 
io.netty.util.internal.chmv8.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 accidentally share a ThreadLocalRandom across multiple threads.

This class also provides additional commonly used bounded random generation methods. //since 1.7 //author Doug Lea

See Also:

  • Nested Class Summary

    Nested classes/interfaces inherited from interface java.util.random.RandomGenerator

    java.util.random.RandomGenerator.ArbitrarilyJumpableGenerator, java.util.random.RandomGenerator.JumpableGenerator, java.util.random.RandomGenerator.LeapableGenerator, java.util.random.RandomGenerator.SplittableGenerator, java.util.random.RandomGenerator.StreamableGenerator

  • Method Summary

    Modifier and Type
    Method
    Description
    static ThreadLocalRandom
    current()
    Returns the current thread's ThreadLocalRandom.
    static long
    getInitialSeedUniquifier()
     
    protected int
    next(int bits)
     
    double
    nextDouble(double n)
    Returns a pseudorandom, uniformly distributed double value between 0 (inclusive) and the specified value (exclusive).
    double
    nextDouble(double least, double bound)
    Returns a pseudorandom, uniformly distributed value between the given least value (inclusive) and bound (exclusive).
    int
    nextInt(int least, int bound)
    Returns a pseudorandom, uniformly distributed value between the given least value (inclusive) and bound (exclusive).
    long
    nextLong(long n)
    Returns a pseudorandom, uniformly distributed value between 0 (inclusive) and the specified value (exclusive).
    long
    nextLong(long least, long bound)
    Returns a pseudorandom, uniformly distributed value between the given least value (inclusive) and bound (exclusive).
    static void
    setInitialSeedUniquifier(long initialSeedUniquifier)
     
    void
    setSeed(long seed)
    Throws UnsupportedOperationException.

    Methods inherited from class java.util.Random

    doubles, doubles, doubles, doubles, from, ints, ints, ints, ints, longs, longs, longs, longs, nextBoolean, nextBytes, nextDouble, nextFloat, nextGaussian, nextInt, nextInt, nextLong

    Methods inherited from class java.lang.Object

    clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

    Methods inherited from interface java.util.random.RandomGenerator

    isDeprecated, nextExponential, nextFloat, nextFloat, nextGaussian

  • Method Details

    • setInitialSeedUniquifier

      public static void setInitialSeedUniquifier(long initialSeedUniquifier)

    • getInitialSeedUniquifier

      public static long getInitialSeedUniquifier()

    • current

      public static ThreadLocalRandom current()
      Returns the current thread's ThreadLocalRandom.
      Returns:
      the current thread's ThreadLocalRandom

    • setSeed

      public void setSeed(long seed)
      Throws UnsupportedOperationException. Setting seeds in this generator is not supported.
      Overrides:
      setSeed in class Random
      Throws:
      UnsupportedOperationException - always

    • next

      protected int next(int bits)
      Overrides:
      next in class Random

    • nextInt

      public int nextInt(int least, int bound)
      Returns a pseudorandom, uniformly distributed value between the given least value (inclusive) and bound (exclusive).
      Parameters:
      least - the least value returned
      bound - the upper bound (exclusive)
      Returns:
      the next value
      Throws:
      IllegalArgumentException - if least greater than or equal to bound

    • nextLong

      public long nextLong(long n)
      Returns a pseudorandom, uniformly distributed value between 0 (inclusive) and the specified value (exclusive).
      Parameters:
      n - the bound on the random number to be returned. Must be positive.
      Returns:
      the next value
      Throws:
      IllegalArgumentException - if n is not positive

    • nextLong

      public long nextLong(long least, long bound)
      Returns a pseudorandom, uniformly distributed value between the given least value (inclusive) and bound (exclusive).
      Parameters:
      least - the least value returned
      bound - the upper bound (exclusive)
      Returns:
      the next value
      Throws:
      IllegalArgumentException - if least greater than or equal to bound

    • nextDouble

      public double nextDouble(double n)
      Returns a pseudorandom, uniformly distributed double value between 0 (inclusive) and the specified value (exclusive).
      Parameters:
      n - the bound on the random number to be returned. Must be positive.
      Returns:
      the next value
      Throws:
      IllegalArgumentException - if n is not positive

    • nextDouble

      public double nextDouble(double least, double bound)
      Returns a pseudorandom, uniformly distributed value between the given least value (inclusive) and bound (exclusive).
      Parameters:
      least - the least value returned
      bound - the upper bound (exclusive)
      Returns:
      the next value
      Throws:
      IllegalArgumentException - if least greater than or equal to bound