How to generate random integers in a range

Question

Possible Duplicate:
Generating random number in a range with Java

This feels pretty silly, but I'm not sure how to create a random integer, giving it a specific range to allow. I was trying to make it generate random numbers between -1 and 1. I tried doing that, but the nextInt part doesn't allow two parameters to be put within the parentheses. Am I supposed to be using something different?

import java.util.Random;

public class Testttterrrr {

    /**
     * @param args
     */
    public static void main(String[] args) {
        Random rng = new Random();
        for (int i=0;i < 10; i++)
        {
        int pepe = 0;
        pepe = rng.nextInt(1, 1-2);
        System.out.println(pepe);
        }
    }

}

lol @ `public class Testttterrrr`. I remember holding the key down longer and longer to make a unique class name. — goat, Oct 24 '12 at 23:30
Hehe well I was writing a different program, but I seriously forgot how to include negative integers. So I just made a new project for simplicity. — Sozziko, Oct 24 '12 at 23:33

score 6 · Accepted Answer · answered Oct 24 '12 at 23:24

6

You could do

pepe = rng.nextInt(3) - 1;

rng.nextInt(3) returns a random element in the set {0, 1, 2} - therefore subtracting 1 returns a random element in the set {-1, 0, 1}, as desired.

Relevant documentation:

nextInt

answered Oct 24 '12 at 23:24

arshajii

127,459
24
238
287

score 4 · Answer 2 · answered Oct 24 '12 at 23:23

4

Try this statement: int pepe = rng.nextInt(3) - 1;

answered Oct 24 '12 at 23:23

Juvanis

25,802
5
69
87

score 4 · Answer 3 · answered Oct 24 '12 at 23:24

4

Use

pepe = rng.nextInt(3) - 1;

To return random sequences of -1, 0, 1.

rng.nextInt(3)

returns a random number in the interval [0..2]. Subtract 1 and you get the interval [-1..1].

answered Oct 24 '12 at 23:24

Jim Garrison

85,615
20
155
190

score 3 · Answer 4 · answered Oct 24 '12 at 23:33

3

pepe = rng.nextInt(3) - 1;

the random number will be either 0, 1, or 2. then subtracting 1 will give you either -1, 0, or 1 just like you want

answered Oct 24 '12 at 23:33

Kailua Bum

1,368
7
25
40

How to generate random integers in a range

4 Answers4