Package io.github.olyutorskii.aletojio

Class BoundRnd

java.lang.Object

io.github.olyutorskii.aletojio.BoundRnd

public class BoundRnd
extends Object

Bounded random integer value [0,bound) generator.

Random source is RndInt32.

This implementation uses a fast algorithm(Nearly Divisionless) that does not use a division(/) or remainder(%) but bitmask and right-shift.

Modulo bias removal may consume multiple 32-bit random numbers per one output.

See Also:

• Fast Random Integer Generation in an Interval (arXiv)
• Nearly Divisionless Random Integer Generation On Various Systems

Constructor Summary

Constructors

Constructor	Description
BoundRnd(RndInt32 rnd, int bound)	Constructor for [0,N) bounded random number.

Method Summary

Modifier and Type	Method	Description
int	next()	Return next bounded random number.

Methods inherited from class java.lang.Object

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

Constructor Details

BoundRnd

public BoundRnd(RndInt32 rnd,
 int bound)
         throws IllegalArgumentException

Constructor for [0,N) bounded random number.

N is upper bound(exclusive).

Parameters:

rnd - 32bit random number generator

bound - upper bound(exclusive) must be 2 or more

Throws:

NullPointerException - argument is null

IllegalArgumentException - toosmall bound

Method Details

next

public int next()

Return next bounded random number.

Returns:

[0, bound) random number