Random Number Algorithm - Implementation in Java

Question

Can anyone please suggest me a random number algorithm that I can use for implementation in java? I don't want to use the Math.random() function.

Note: I want to write my own random number generation function in java; therefore for I am looking for an algorithm that I can use.

Are you looking for [Random](http://docs.oracle.com/javase/7/docs/api/java/util/Random.html) ? — donfuxx, May 05 '14 at 00:21
[Generating random numbers in a range with Java](http://stackoverflow.com/q/363681) — Bernhard Barker, May 05 '14 at 00:22
You will need to seed system time... [System.currentTimeMillis()](http://docs.oracle.com/javase/7/docs/api/java/lang/System.html#currentTimeMillis()) — Mr. Polywhirl, May 05 '14 at 00:34
Check out this question for more suggestions: [SO: How to generate a random number from scratch](http://stackoverflow.com/questions/1967491/how-to-generate-a-random-number-from-scratch) — Mr. Polywhirl, May 05 '14 at 00:39
@kdgregory I want to write my own random number generation function in java; therefore for I am looking for an algorithm that I can use. — akhouri, May 05 '14 at 00:46
@vas - I asked because the reason will determine what sort of answer is appropriate. For example: you need crytographically-secure randomness. If you just want to reinvent the wheel, then Google turns up lots (2MM+) of results. And since you have no real requirements, you could have picked one arbitrarily. — kdgregory, May 05 '14 at 11:33
@kdgregory thanks for your suggestions; i will try google search for some algos for my research. — akhouri, May 06 '14 at 00:37

score 2 · Answer 1 · edited May 05 '14 at 01:32

2

I think your question actually language-agnostic, and shouldn't be specifically java. Also, I think it's very easy to find information on things like this. Look at the wiki pages for Pseudorandom number generator and Random number generation. If you're looking for something simple (relatively) look at the XORshift RNG

uint32_t xor128(void) { //A C version from wiki
  static uint32_t x = 123456789;
  static uint32_t y = 362436069;
  static uint32_t z = 521288629;
  static uint32_t w = 88675123;
  uint32_t t;

  t = x ^ (x << 11);
  x = y; y = z; z = w;
  return w = w ^ (w >> 19) ^ (t ^ (t >> 8));
}

Or in Java:

public class IsNotFour {
    int x = 123456789;
    int y = 362436069;
    int z = 521288629;
    int w = 88675123;

    int xor128() { // A converted C version from wiki
        int t = x ^ (x << 11);
        x = y;
        y = z;
        z = w;
        w = w ^ (w >>> 19) ^ (t ^ (t >>> 8));
        return w; 
    }
}

Note that x, y, z and w together make the seed.

edited May 05 '14 at 01:32

Maarten Bodewes

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answered May 05 '14 at 01:07

Kyranstar

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You're right, who needs complicated strange bit shifty functions when you could just use [xkcd's?](http://xkcd.com/221/) It's much more random. – Kyranstar May 05 '14 at 01:12
Just joking, as I did not see a specific seed. Are the first outputs `DCA345EA, 1B5116E6, 951049AA, D88D00B0`? – Maarten Bodewes May 05 '14 at 01:18
Yes, I got that too. The values for x, y, z, and w are actually the seeds, so those can be tweaked. – Kyranstar May 05 '14 at 01:25
Yeah, I guessed that, I've added Java code as using `>>>` instead of `>>` is a bit tricky. – Maarten Bodewes May 05 '14 at 01:33

Random Number Algorithm - Implementation in Java

1 Answers1