java.util

Class Random

java.lang.Object

java.util.Random

public class Random
extends Object

This class provides methods that generates pseudo-random numbers of different types, such as int, long, double, and float. It follows the algorithms specified in the JRE javadoc. This emulated version of Random is not serializable.

Constructor Summary

Constructors

Constructor and Description
Random() Construct a random generator with the current time of day in milliseconds plus a unique counter value as the initial state.
Random(long seed) Construct a random generator with the given seed as the initial state.

Method Summary

Modifier and Type	Method and Description
protected int	next(int bits) Returns a pseudo-random uniformly distributed int value of the number of bits specified by the argument bits as described by Donald E.
boolean	nextBoolean() Returns the next pseudo-random, uniformly distributed boolean value generated by this generator.
void	nextBytes(byte[] buf) Modifies the byte array by a random sequence of bytes generated by this random number generator.
double	nextDouble() Generates a normally distributed random double number between 0.0 inclusively and 1.0 exclusively.
float	nextFloat() Generates a normally distributed random float number between 0.0 inclusively and 1.0 exclusively.
double	nextGaussian() Pseudo-randomly generates (approximately) a normally distributed double value with mean 0.0 and a standard deviation value of 1.0 using the polar method of G.
int	nextInt() Generates a uniformly distributed 32-bit int value from the random number sequence.
int	nextInt(int n) Returns a new pseudo-random int value which is uniformly distributed between 0 (inclusively) and the value of n (exclusively).
long	nextLong() Generates a uniformly distributed 64-bit integer value from the random number sequence.
void	setSeed(long seed) Modifies the seed a using linear congruential formula presented in The Art of Computer Programming, Volume 2, Section 3.2.1.

Methods inherited from class java.lang.Object

equals, finalize, getClass, hashCode, toString

Constructor Detail

Random

public Random()

Construct a random generator with the current time of day in milliseconds plus a unique counter value as the initial state.

See Also:

setSeed(long)

Random

public Random(long seed)

Construct a random generator with the given seed as the initial state.

Parameters:

seed - the seed that will determine the initial state of this random number generator.

See Also:

setSeed(long)

Method Detail

nextBoolean

public boolean nextBoolean()

Returns the next pseudo-random, uniformly distributed boolean value generated by this generator.

Returns:

a pseudo-random, uniformly distributed boolean value.

nextBytes

public void nextBytes(byte[] buf)

Modifies the byte array by a random sequence of bytes generated by this random number generator.

Parameters:

buf - non-null array to contain the new random bytes.

See Also:

next(int)

nextDouble

public double nextDouble()

Generates a normally distributed random double number between 0.0 inclusively and 1.0 exclusively.

Returns:

a random double in the range [0.0 - 1.0)

See Also:

nextFloat()

nextFloat

public float nextFloat()

Generates a normally distributed random float number between 0.0 inclusively and 1.0 exclusively.

Returns:

float a random float number between [0.0 and 1.0)

See Also:

nextDouble()

nextGaussian

public double nextGaussian()

Pseudo-randomly generates (approximately) a normally distributed double value with mean 0.0 and a standard deviation value of 1.0 using the polar method of G. E. P. Box, M. E. Muller, and G. Marsaglia, as described by Donald E. Knuth in The Art of Computer Programming, Volume 2: Seminumerical Algorithms, section 3.4.1, subsection C, algorithm P.

Returns:

a random double

See Also:

nextDouble()

nextInt

public int nextInt()

Generates a uniformly distributed 32-bit int value from the random number sequence.

Returns:

a uniformly distributed int value.

See Also:

Integer.MAX_VALUE, Integer.MIN_VALUE, next(int), nextLong()

nextInt

public int nextInt(int n)

Returns a new pseudo-random int value which is uniformly distributed between 0 (inclusively) and the value of n (exclusively).

Parameters:

n - the exclusive upper border of the range [0 - n).

Returns:

a random int.

nextLong

public long nextLong()

Generates a uniformly distributed 64-bit integer value from the random number sequence.

Returns:

64-bit random integer.

See Also:

Integer.MAX_VALUE, Integer.MIN_VALUE, next(int), nextInt(), nextInt(int)

setSeed

public void setSeed(long seed)

Modifies the seed a using linear congruential formula presented in The Art of Computer Programming, Volume 2, Section 3.2.1.

Parameters:

seed - the seed that alters the state of the random number generator.

See Also:

next(int), Random(), Random(long)

next

protected int next(int bits)

Returns a pseudo-random uniformly distributed int value of the number of bits specified by the argument bits as described by Donald E. Knuth in The Art of Computer Programming, Volume 2: Seminumerical Algorithms, section 3.2.1.

Parameters:

bits - number of bits of the returned value.

Returns:

a pseudo-random generated int number.

See Also:

nextBytes(byte[]), nextDouble(), nextFloat(), nextInt(), nextInt(int), nextGaussian(), nextLong()