totalcross.util

Class Random

java.lang.Object

totalcross.util.Random

public class Random
extends java.lang.Object

This is a simple Linear Congruential Generator which produces random numbers in the range [0,2^31), derived from ran0 in Numerical Recipies. Note that ran0 isn't wonderfully random -- there are much better generators out there -- but it'll do the job, and it's fast and has low memory consumption.

Here's a sample of how to use the Random class:

    Random r = new Random(0x1234); // the use of the same key is sometimes desirable
    for (...)
    {
       int nextRandomInt = r.between(0,10);
       char nextRandomChar = r.between('a','z');
       ...
    }
    

Constructor Summary

Constructors

Constructor and Description
Random() Randomizes based on the current timestamp
Random(int _seed) The only reasonable seeds are between 0 and 2^31 inclusive; if you're negative, it'll get the absolute value of it.

Method Summary

Modifier and Type	Method and Description
char	between(char s, char e) Returns a random character between the given region.
int	between(int s, int e) Returns random integer in the given region.
int	getSeed() Returns the first seed used
protected int	next(int bits) Bits should be <= 31
double	nextDouble() Returns a double floating-point value in the half-open range [0,1).
int	nextInt(int n) Returns an integer in the range [0,n).

Methods inherited from class java.lang.Object

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

Constructor Detail

Random

public Random(int _seed)

The only reasonable seeds are between 0 and 2^31 inclusive; if you're negative, it'll get the absolute value of it.

Random

public Random()

Randomizes based on the current timestamp

Method Detail

next

protected int next(int bits)

Bits should be <= 31

nextDouble

public double nextDouble()

Returns a double floating-point value in the half-open range [0,1).

nextInt

public int nextInt(int n)

Returns an integer in the range [0,n). n must be > 0, else -1 is returned.

See Also:

between(char, char), between(int, int)

between

public char between(char s,
                    char e)

Returns a random character between the given region. Eg: between('a', 'e') returns a random character between 'a' and 'e'.

Parameters:

s - the start character in the range

e - the ending character in the range

between

public int between(int s,
                   int e)

Returns random integer in the given region. Eg: rand(1, 10) returns a random integer in the range of 1 to 10, inclusive. Note that if s == e, it will return in the range s and e+1.

Parameters:

s - the start number in the range

e - the ending number in the range

getSeed

public int getSeed()

Returns the first seed used