Generates Random Integers in a Specific Range

import java.util.Random;



/** Generate random integers in a certain range. */

public final class RandomRange {

 

  public static final void main(String... aArgs){

    log("Generating random integers in the range 1..10.");

   

    int START = 1;

    int END = 10;

    Random random = new Random();

    for (int idx = 1; idx <= 10; ++idx){

      showRandomInteger(START, END, random);

    }

   

    log("Done.");

  }

 

  private static void showRandomInteger(int aStart, int aEnd, Random aRandom){

    if (aStart > aEnd) {

      throw new IllegalArgumentException("Start cannot exceed End.");

    }

    //get the range, casting to long to avoid overflow problems

    long range = (long)aEnd - (long)aStart + 1;

    // compute a fraction of the range, 0 <= frac < range

    long fraction = (long)(range * aRandom.nextDouble());

    int randomNumber =  (int)(fraction + aStart);  

    log("Generated : " + randomNumber);

  }

 

  private static void log(String aMessage){

    System.out.println(aMessage);

  }

}





An example run of this class:

Generating random integers in the range 1..10.

Generated : 9

Generated : 3

Generated : 3

Generated : 9

Generated : 4

Generated : 1

Generated : 3

Generated : 9

Generated : 10

Generated : 10

Done.