physis.core.random
Class JavaUtilRandom

java.lang.Object
  |
  +--physis.core.random.Randomness
        |
        +--physis.core.random.JavaUtilRandom

public class JavaUtilRandom

extends Randomness

This is essentially the guts of java.util.Random as of jdk1.3. Thu 31-May-2001 00:13 bush from the header in java.util.Random: An instance of this class is used to generate a stream of pseudorandom numbers. The class uses a 48-bit seed, which is modified using a linear congruential formula. (See Donald Knuth, The Art of Computer Programming, Volume 2, Section 3.2.1.)

If two instances of Random are created with the same seed, and the same sequence of method calls is made for each, they will generate and return identical sequences of numbers. In order to guarantee this property, particular algorithms are specified for the class Random. Java implementations must use all the algorithms shown here for the class Random, for the sake of absolute portability of Java code. However, subclasses of class Random are permitted to use other algorithms, so long as they adhere to the general contracts for all the methods.

Field Summary

private static long	addend
private static long	mask
private static long	multiplier
private long	seed

Constructor Summary

JavaUtilRandom(long seed)

Method Summary

static void	main(java.lang.String[] args)
int	next(int bits) Generates the next pseudorandom number.
void	setSeed(long seed)

Methods inherited from class physis.core.random.Randomness

nextBoolean, nextBoolean, nextByte, nextBytes, nextDouble, nextFloat, nextInt, nextInt, nextLong, raw

Methods inherited from class java.lang.Object

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

Field Detail

seed

private long seed

multiplier

private static final long multiplier

addend

private static final long addend

mask

private static final long mask

Constructor Detail

JavaUtilRandom

public JavaUtilRandom(long seed)

Method Detail

setSeed

public final void setSeed(long seed)

next

public final int next(int bits)

Generates the next pseudorandom number. Subclass should override this, as this is used by all other methods.

The general contract of next is that it returns an int value and if the argument bits is between 1 and 32 (inclusive), then that many low-order bits of the returned value will be (approximately) independently chosen bit values, each of which is (approximately) equally likely to be 0 or 1. The method next is implemented by class Random as follows:

 synchronized protected int next(int bits) {
       seed = (seed * 0x5DEECE66DL + 0xBL) & ((1L << 48) - 1);
       return (int)(seed >>> (48 - bits));
 }

This is a linear congruential pseudorandom number generator, as defined by D. H. Lehmer and described by Donald E. Knuth in The Art of Computer Programming, Volume 2: Seminumerical Algorithms, section 3.2.1.

Overrides:

next in class Randomness

Parameters:

bits - random bits

Returns:

the next pseudorandom value from this random number generator's sequence.

Since:

JDK1.1

main

public static void main(java.lang.String[] args)