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Re: Random Int between x and y
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Re: Random Int between x and y


  • Subject: Re: Random Int between x and y
  • From: Kieran Kelleher <email@hidden>
  • Date: Wed, 10 Mar 2004 11:04:12 -0500

Correct me if I'm wrong, but I think casting using (int) will skew the results due to rounding down truncation, so better to use Math.round instead of (int) cast. The probability of having the result be equal to m2 is greatly reduced using the (int) cast.

It just occurred to me, probably m1 and m2 should be converted to doubles and make m1 = m1 - 0.49999 and make m2 = m2 + 0.49999 to get true probability across the range of numbers since each possible number has a +/- 0.5 spread each side of the final integer selection.

-Kieran

On Mar 10, 2004, at 9:47 AM, Michael Engelhart wrote:

To be more specific:

public class Test {
	public static void main(String args[]) {
		int m1 = 10;
		int m2 = 25;
		int rn = (int) ((Math.random() * (m2-m1)) + m1);
		System.out.println(rn);
	}
}


Mike

On Mar 10, 2004, at 9:33 AM, email@hidden wrote:

Hi David

On 10 Mar 2004, at 13:46, David Griffith wrote:

Hi all,

Is there an easy way to generate a random int in the range x <= int <= y?
I have found a couple of methods but they don't appear to do what I need.

Use java.lang.Math.random().

If you need a cryptographically strong number, you can look at java.security.SecureRandom

Cheers,
-- Denis.

I'm sure there's a simple answer....

Regards,
Dave.
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  • Follow-Ups:
    • Re: Random Int between x and y
      • From: David Griffith <email@hidden>
References: 
 >Random Int between x and y (From: David Griffith <email@hidden>)
 >Re: Random Int between x and y (From: email@hidden)
 >Re: Random Int between x and y (From: Michael Engelhart <email@hidden>)

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