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javarandom

Java random always returns the same number when I set the seed?

I require help with a random number generator I am creating. My code is as follows (inside a class called numbers):

public int random(int i){
    Random randnum = new Random();
    randnum.setSeed(123456789);
    return randnum.nextInt(i);
}

When I call this method from another class (in order to generate a random number), it always returns the same number. For example if I were to do:

System.out.println(numbers.random(10));
System.out.print(numbers.random(10));

it always prints the same number e.g. 5 5. What do I have to do so that it prints two different numbers e.g. 5 8

It is mandatory that I set the seed.

Thanks

Solution

  • You need to share the Random() instance across the whole class:

    public class Numbers {
    Random randnum;

    public Numbers() {
        randnum = new Random();
        randnum.setSeed(123456789);
    }

    public int random(int i){
        return randnum.nextInt(i);
    }
}