Random number help

[jgonzalez14]

Hi all,

I need help with a random number feature. I want a random number between 1 and 26 (including 1 and 26). I have this

letter =(int) (Math.random() * 26 + 1);

Since Math.random() is 0 - .9999999, how do i get whole numbers?

should I do this:

so right now i am not getting accurate whole numbers. can anyone help?


Thanks

[Nicholas Jordan]

Random has a nextInt() that takes an upper bound. There are short and well known ways to get the number in a range.

[jgonzalez14]

I was looking into that but I have to keep the Random() function. Thanks tho. Is it possible to get some insight with the Random feature?

[Nicholas Jordan]

Well, in general what we do is int num = Math.random() times range plus floor. It is simple, you just have to do a timeout and think about it.

Some number times ( 0 - 1 ) gives, bascially, zero to the number. Then we often have a range so it is upper limit minus lower limit times random plus floor.

[racerxadam]

I created a quick test class and only got numbers between 1 and 26 inclusive using basically what you posted.

public class TestRandom {

	/**
	 * @param args
	 */
	public static void main(String[] args) {

		for (int i = 0; i < 50000; i++) {
			int letter = (int)(Math.random() * 26 + 1);
			System.out.println(letter);
			if(letter == 0 || letter > 26){
				throw new RuntimeException("The value is out of range" + letter);
			}
		}
	}
}

[Eranga]

You can do this easily in this way as well.

    public static void main(String[] args) {
        Random randomGenerator = new Random();
        
        for(int i = 0; i < 15; i++) {
            int j = randomGenerator.nextInt(26);
            System.out.println(j + 1);
        }
    }