File	Doc	Category	Size	Date	Package
Random.java	API Doc	phoneME MR2 API (J2ME)	7702	Wed May 02 17:59:54 BST 2007	java.util

Random

• java.lang.Object

Fields Summary
private long	seed The internal state associated with this pseudorandom number generator. (The specs for the methods in this class describe the ongoing computation of this value.)
private static final long	multiplier
private static final long	addend
private static final long	mask
private static final int	BITS_PER_BYTE
private static final int	BYTES_PER_INT

Constructors Summary
public Random() Creates a new random number generator. Its seed is initialized to a value based on the current time: public Random() { this(System.currentTimeMillis()); } see java.lang.System#currentTimeMillis() this(System.currentTimeMillis());
public Random(long seed) Creates a new random number generator using a single long seed: public Random(long seed) { setSeed(seed); } Used by method next to hold the state of the pseudorandom number generator. param seed the initial seed. see java.util.Random#setSeed(long) setSeed(seed);

Methods Summary
protected synchronized 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. param bits random bits return the next pseudorandom value from this random number generator's sequence. since JDK1.1 long nextseed = (seed * multiplier + addend) & mask; seed = nextseed; return (int)(nextseed >>> (48 - bits));
public int	nextInt() Returns the next pseudorandom, uniformly distributed int value from this random number generator's sequence. The general contract of nextInt is that one int value is pseudorandomly generated and returned. All 232 possible int values are produced with (approximately) equal probability. The method nextInt is implemented by class Random as follows: public int nextInt() { return next(32); } return the next pseudorandom, uniformly distributed int value from this random number generator's sequence. return next(32);
public long	nextLong() Returns the next pseudorandom, uniformly distributed long value from this random number generator's sequence. The general contract of nextLong is that one long value is pseudorandomly generated and returned. All 264 possible long values are produced with (approximately) equal probability. The method nextLong is implemented by class Random as follows: public long nextLong() { return ((long)next(32) << 32) + next(32); } return the next pseudorandom, uniformly distributed long value from this random number generator's sequence. // it's okay that the bottom word remains signed. return ((long)(next(32)) << 32) + next(32);
public synchronized void	setSeed(long seed) Sets the seed of this random number generator using a single long seed. The general contract of setSeed is that it alters the state of this random number generator object so as to be in exactly the same state as if it had just been created with the argument seed as a seed. The method setSeed is implemented by class Random as follows: synchronized public void setSeed(long seed) { this.seed = (seed ^ 0x5DEECE66DL) & ((1L << 48) - 1); } The implementation of setSeed by class Random happens to use only 48 bits of the given seed. In general, however, an overriding method may use all 64 bits of the long argument as a seed value. param seed the initial seed. this.seed = (seed ^ multiplier) & mask;