Package org.moeaframework.core

Class PRNG

java.lang.Object
org.moeaframework.core.PRNG
public class PRNG extends Object
Static methods for generating random or pseudo-random numbers. Any source of randomness implementing the Random interface can be used as the random source.

PRNG relies on an underlying source of randomness, and inherits thread safety from the underlying implementation. Unless the underlying implementation is known to be thread-safe, assume that PRNG is not thread-safe.

  • Method Summary

    Modifier and Type
    Method
    Description
    static Random
    getRandom()
    Returns the source of randomness currently used.
    static boolean
    nextBoolean()
    Returns the next random, uniformly distributed boolean value.
    static double
    nextDouble()
    Returns the next random, uniformly distributed double value between 0.0 and 1.0.
    static double
    nextDouble(double min, double max)
    Returns the next random, uniformly distributed double value between min and max.
    static float
    nextFloat()
    Returns the next random, uniformly distributed float value between 0.0 and 1.0.
    static float
    nextFloat(float min, float max)
    Returns the next random, uniformly distributed float value between min and max.
    static double
    nextGaussian()
    Returns the next random, Gaussian distributed double value with mean 0.0 and standard deviation 1.0.
    static double
    nextGaussian(double mean, double stdev)
    Returns the next random, Gaussian distributed double value with mean mean and standard deviation stdev.
    static int
    nextInt()
    Returns the next random, uniformly distributed int value between Integer.MIN_VALUE and Integer.MAX_VALUE .
    static int
    nextInt(int n)
    Returns the next random, uniformly distributed int value between 0 (inclusive) and n (exclusive).
    static int
    nextInt(int min, int max)
    Returns the next random, uniformly distributed int value between min and max (both inclusive).
    static <T> T
    nextItem(List<T> list)
    Returns a randomly selected item from the specified list.
    static <T> T
    nextItem(Set<T> set)
    Returns a randomly selected item from the specified set.
    static void
    setRandom(Random random)
    Sets the source of randomness to be used.
    static void
    setSeed(long seed)
    While the preferred method for seeding PRNGs is through the setRandom method since methods providing more entropy may be available to specific implementations, this method is intended to provide a uniform interface for setting the seed.
    static void
    shuffle(boolean[] array)
    Shuffles the elements of the specified array using the same algorithm as Collections.shuffle(java.util.List<?>).
    static void
    shuffle(byte[] array)
    Shuffles the elements of the specified array using the same algorithm as Collections.shuffle(java.util.List<?>).
    static void
    shuffle(double[] array)
    Shuffles the elements of the specified array using the same algorithm as Collections.shuffle(java.util.List<?>).
    static void
    shuffle(float[] array)
    Shuffles the elements of the specified array using the same algorithm as Collections.shuffle(java.util.List<?>).
    static void
    shuffle(int[] array)
    Shuffles the elements of the specified array using the same algorithm as Collections.shuffle(java.util.List<?>).
    static void
    shuffle(long[] array)
    Shuffles the elements of the specified array using the same algorithm as Collections.shuffle(java.util.List<?>).
    static void
    shuffle(short[] array)
    Shuffles the elements of the specified array using the same algorithm as Collections.shuffle(java.util.List<?>).
    static <T> void
    shuffle(List<T> list)
    Shuffles the elements of the specified list by invoking the Collections.shuffle(java.util.List<?>) method with the internal Random in this PRNG.
    static <T> void
    shuffle(T[] array)
    Shuffles the elements of the specified array using the same algorithm as Collections.shuffle(java.util.List<?>).

    Methods inherited from class java.lang.Object

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

  • Method Details

    • setSeed

      public static void setSeed(long seed)
      While the preferred method for seeding PRNGs is through the setRandom method since methods providing more entropy may be available to specific implementations, this method is intended to provide a uniform interface for setting the seed.
      Parameters:
      seed - the new seed

    • setRandom

      public static void setRandom(Random random)
      Sets the source of randomness to be used.
      Parameters:
      random - the source of randomness to be used

    • getRandom

      public static Random getRandom()
      Returns the source of randomness currently used.
      Returns:
      the source of randomness currently used

    • nextFloat

      public static float nextFloat()
      Returns the next random, uniformly distributed float value between 0.0 and 1.0.
      Returns:
      the next random, uniformly distributed float value between 0.0 and 1.0

    • nextFloat

      public static float nextFloat(float min, float max)
      Returns the next random, uniformly distributed float value between min and max.
      Parameters:
      min - the minimum value (inclusive)
      max - the maximum value (exclusive)
      Returns:
      the next random, uniformly distributed float value between min and max

    • nextDouble

      public static double nextDouble()
      Returns the next random, uniformly distributed double value between 0.0 and 1.0.
      Returns:
      the next random, uniformly distributed double value between 0.0 and 1.0

    • nextDouble

      public static double nextDouble(double min, double max)
      Returns the next random, uniformly distributed double value between min and max.
      Parameters:
      min - the minimum value (inclusive)
      max - the maximum value (exclusive)
      Returns:
      the next random, uniformly distributed double value between min and max

    • nextInt

      public static int nextInt()
      Returns the next random, uniformly distributed int value between Integer.MIN_VALUE and Integer.MAX_VALUE .
      Returns:
      the next random, uniformly distributed int value between Integer.MIN_VALUE and Integer.MAX_VALUE.

    • nextInt

      public static int nextInt(int n)
      Returns the next random, uniformly distributed int value between 0 (inclusive) and n (exclusive).
      Parameters:
      n - the maximum value (exclusive)
      Returns:
      the next random, uniformly distributed int value between 0 (inclusive) and n (exclusive).

    • nextInt

      public static int nextInt(int min, int max)
      Returns the next random, uniformly distributed int value between min and max (both inclusive).
      Parameters:
      min - the minimum value (inclusive)
      max - the maximum value (inclusive)
      Returns:
      the next random, uniformly distributed int value between min and max (both inclusive).

    • nextBoolean

      public static boolean nextBoolean()
      Returns the next random, uniformly distributed boolean value.
      Returns:
      the next random, uniformly distributed boolean value.

    • nextGaussian

      public static double nextGaussian()
      Returns the next random, Gaussian distributed double value with mean 0.0 and standard deviation 1.0.
      Returns:
      the next random, Gaussian distributed double value with mean 0.0 and standard deviation 1.0.

    • nextGaussian

      public static double nextGaussian(double mean, double stdev)
      Returns the next random, Gaussian distributed double value with mean mean and standard deviation stdev.
      Parameters:
      mean - the mean
      stdev - the standard deviation
      Returns:
      the next random, Gaussian distributed double value with mean mean and standard deviation stdev.

    • shuffle

      public static <T> void shuffle(T[] array)
      Shuffles the elements of the specified array using the same algorithm as Collections.shuffle(java.util.List<?>).
      Type Parameters:
      T - the type of element stored in the array
      Parameters:
      array - the array to be shuffled

    • shuffle

      public static void shuffle(double[] array)
      Shuffles the elements of the specified array using the same algorithm as Collections.shuffle(java.util.List<?>).
      Parameters:
      array - the array to be shuffled

    • shuffle

      public static void shuffle(float[] array)
      Shuffles the elements of the specified array using the same algorithm as Collections.shuffle(java.util.List<?>).
      Parameters:
      array - the array to be shuffled

    • shuffle

      public static void shuffle(long[] array)
      Shuffles the elements of the specified array using the same algorithm as Collections.shuffle(java.util.List<?>).
      Parameters:
      array - the array to be shuffled

    • shuffle

      public static void shuffle(int[] array)
      Shuffles the elements of the specified array using the same algorithm as Collections.shuffle(java.util.List<?>).
      Parameters:
      array - the array to be shuffled

    • shuffle

      public static void shuffle(short[] array)
      Shuffles the elements of the specified array using the same algorithm as Collections.shuffle(java.util.List<?>).
      Parameters:
      array - the array to be shuffled

    • shuffle

      public static void shuffle(byte[] array)
      Shuffles the elements of the specified array using the same algorithm as Collections.shuffle(java.util.List<?>).
      Parameters:
      array - the array to be shuffled

    • shuffle

      public static void shuffle(boolean[] array)
      Shuffles the elements of the specified array using the same algorithm as Collections.shuffle(java.util.List<?>).
      Parameters:
      array - the array to be shuffled

    • shuffle

      public static <T> void shuffle(List<T> list)
      Shuffles the elements of the specified list by invoking the Collections.shuffle(java.util.List<?>) method with the internal Random in this PRNG.
      Type Parameters:
      T - the type of elements stored in the list
      Parameters:
      list - the list to be shuffled

    • nextItem

      public static <T> T nextItem(List<T> list)
      Returns a randomly selected item from the specified list.
      Type Parameters:
      T - the type of the elements stored in the list
      Parameters:
      list - the list from which the item is randomly selected
      Returns:
      a randomly selected item from the specified list

    • nextItem

      public static <T> T nextItem(Set<T> set)
      Returns a randomly selected item from the specified set.
      Type Parameters:
      T - the type of the elements stored in the set
      Parameters:
      set - the set from which the item is randomly selected
      Returns:
      a randomly selected item from the specified set