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Random Numbers in a Deterministic Way

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Problem

You want to generate random numbers in a deterministic way, i.e. for each execution of the program, you want to get the same set of random numbers.

I needed such a solution in a program in which I needed to pick some random elements from a matrix, but I also needed a guarantee that repeated execution of the program will produce exactly the same output.

Solution

import java.util.Random;

Random rand = new Random(20090925);   // trick: specify a seed

for (int i = 0; i < 10; ++i)
{
   int pick = rand.nextInt(10);
   System.out.print(pick + " ");
}
System.out.println();

It will produce the set "0 5 4 4 3 2 3 4 6 8" each time you execute this code.

More info: http://java.about.com/od/javautil/a/randomnumbers.htm .