Package com.badlogic.gdx.math

Class RandomXS128

  • All Implemented Interfaces:
    java.io.Serializable
    public class RandomXS128
extends java.util.Random
    This class implements the xorshift128+ algorithm that is a very fast, top-quality 64-bit pseudo-random number generator. The quality of this PRNG is much higher than Random's, and its cycle length is 2128 − 1, which is more than enough for any single-thread application. More details and algorithms can be found here.

    Instances of RandomXS128 are not thread-safe.

    See Also:
    Serialized Form

    • Constructor Summary

      Constructors 
      Constructor Description
      RandomXS128()
      Creates a new random number generator.
      RandomXS128​(long seed)
      Creates a new random number generator using a single long seed.
      RandomXS128​(long seed0, long seed1)
      Creates a new random number generator using two long seeds.

    • Method Summary

      All Methods Instance Methods Concrete Methods 
      Modifier and Type Method Description
      long getState​(int seed)
      Returns the internal seeds to allow state saving.
      protected int next​(int bits)
      This protected method is final because, contrary to the superclass, it's not used anymore by the other methods.
      boolean nextBoolean()
      Returns a pseudo-random, uniformly distributed boolean value from this random number generator's sequence.
      void nextBytes​(byte[] bytes)
      Generates random bytes and places them into a user-supplied byte array.
      double nextDouble()
      Returns a pseudo-random, uniformly distributed double value between 0.0 and 1.0 from this random number generator's sequence.
      float nextFloat()
      Returns a pseudo-random, uniformly distributed float value between 0.0 and 1.0 from this random number generator's sequence.
      int nextInt()
      Returns the next pseudo-random, uniformly distributed int value from this random number generator's sequence.
      int nextInt​(int n)
      Returns a pseudo-random, uniformly distributed int value between 0 (inclusive) and the specified value (exclusive), drawn from this random number generator's sequence.
      long nextLong()
      Returns the next pseudo-random, uniformly distributed long value from this random number generator's sequence.
      long nextLong​(long n)
      Returns a pseudo-random, uniformly distributed long value between 0 (inclusive) and the specified value (exclusive), drawn from this random number generator's sequence.
      void setSeed​(long seed)
      Sets the internal seed of this generator based on the given long value.
      void setState​(long seed0, long seed1)
      Sets the internal state of this generator.

      • Methods inherited from class java.util.Random

        doubles, doubles, doubles, doubles, ints, ints, ints, ints, longs, longs, longs, longs, nextGaussian

      • Methods inherited from class java.lang.Object

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

    • Constructor Detail

      • RandomXS128

        public RandomXS128()
        Creates a new random number generator. This constructor sets the seed of the random number generator to a value very likely to be distinct from any other invocation of this constructor.

        This implementation creates a Random instance to generate the initial seed.

      • RandomXS128

        public RandomXS128​(long seed)
        Creates a new random number generator using a single long seed.
        Parameters:
        seed - the initial seed

      • RandomXS128

        public RandomXS128​(long seed0,
                   long seed1)
        Creates a new random number generator using two long seeds.
        Parameters:
        seed0 - the first part of the initial seed
        seed1 - the second part of the initial seed

    • Method Detail

      • nextLong

        public long nextLong()
        Returns the next pseudo-random, uniformly distributed long value from this random number generator's sequence.

        Subclasses should override this, as this is used by all other methods.

        Overrides:
        nextLong in class java.util.Random

      • next

        protected final int next​(int bits)
        This protected method is final because, contrary to the superclass, it's not used anymore by the other methods.
        Overrides:
        next in class java.util.Random

      • nextInt

        public int nextInt()
        Returns the next pseudo-random, uniformly distributed int value from this random number generator's sequence.

        This implementation uses nextLong() internally.

        Overrides:
        nextInt in class java.util.Random

      • nextInt

        public int nextInt​(int n)
        Returns a pseudo-random, uniformly distributed int value between 0 (inclusive) and the specified value (exclusive), drawn from this random number generator's sequence.

        This implementation uses nextLong() internally.

        Overrides:
        nextInt in class java.util.Random
        Parameters:
        n - the positive bound on the random number to be returned.
        Returns:
        the next pseudo-random int value between 0 (inclusive) and n (exclusive).

      • nextLong

        public long nextLong​(long n)
        Returns a pseudo-random, uniformly distributed long value between 0 (inclusive) and the specified value (exclusive), drawn from this random number generator's sequence. The algorithm used to generate the value guarantees that the result is uniform, provided that the sequence of 64-bit values produced by this generator is.

        This implementation uses nextLong() internally.

        Parameters:
        n - the positive bound on the random number to be returned.
        Returns:
        the next pseudo-random long value between 0 (inclusive) and n (exclusive).

      • nextDouble

        public double nextDouble()
        Returns a pseudo-random, uniformly distributed double value between 0.0 and 1.0 from this random number generator's sequence.

        This implementation uses nextLong() internally.

        Overrides:
        nextDouble in class java.util.Random

      • nextFloat

        public float nextFloat()
        Returns a pseudo-random, uniformly distributed float value between 0.0 and 1.0 from this random number generator's sequence.

        This implementation uses nextLong() internally.

        Overrides:
        nextFloat in class java.util.Random

      • nextBoolean

        public boolean nextBoolean()
        Returns a pseudo-random, uniformly distributed boolean value from this random number generator's sequence.

        This implementation uses nextLong() internally.

        Overrides:
        nextBoolean in class java.util.Random

      • nextBytes

        public void nextBytes​(byte[] bytes)
        Generates random bytes and places them into a user-supplied byte array. The number of random bytes produced is equal to the length of the byte array.

        This implementation uses nextLong() internally.

        Overrides:
        nextBytes in class java.util.Random

      • setSeed

        public void setSeed​(long seed)
        Sets the internal seed of this generator based on the given long value.

        The given seed is passed twice through a hash function. This way, if the user passes a small value we avoid the short irregular transient associated with states having a very small number of bits set.

        Overrides:
        setSeed in class java.util.Random
        Parameters:
        seed - a nonzero seed for this generator (if zero, the generator will be seeded with Long.MIN_VALUE).

      • setState

        public void setState​(long seed0,
                     long seed1)
        Sets the internal state of this generator.
        Parameters:
        seed0 - the first part of the internal state
        seed1 - the second part of the internal state

      • getState

        public long getState​(int seed)
        Returns the internal seeds to allow state saving.
        Parameters:
        seed - must be 0 or 1, designating which of the 2 long seeds to return
        Returns:
        the internal seed that can be used in setState