Class ThreadLocalRandom

java.lang.Object
java.util.Random
org.apache.jmeter.util.ThreadLocalRandom
All Implemented Interfaces:
Serializable, RandomGenerator
public 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 java.util.concurrent.ForkJoinTask (JDK 1.7)) 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.

Since:
2.12
Author:
Doug Lea TODO Remove when minimum Java Version become Java 7
See Also:

  • Method Details

    • 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