Math.random().....any formula to adjust required range?

[Hassan Marzooq]

HELLO ALL
I am looking for a formula or method which takes our required minimum & maximum range and will return numbers within our specified range using Math.random().Possible signature of such method is like this,

            getRandomNumber(double min,double max){
             //Formula for making our desired range                             //           //using Math.random().
             }

Is this thing is presented by some author.?
Best Regards,
Hassan!
[ December 22, 2002: Message edited by: Hassan Marzooq ]

[Maulin Vasavada]

hi Hassan,
i really don't see a problem you are facing. do you want to know how you can generate random numbers between the number range you provide?
if thats the case then try the following code,

class random {
private double MIN = 4.0;
private double MAX = 15.0;
private double DIFF;
random(double min,double max) {
this.MAX = max;
this.MIN = min;
DIFF = MAX - MIN;
}
public double getRandom() {
return DIFF*Math.random()+ MIN; 
}
public static void main(String[] args) {
double max = Double.parseDouble(args[0]);
double min = Double.parseDouble(args[1]);
random r = new random(max,min);
int j = Integer.parseInt(args[2]);
for(int i=0; i < j ;i++) {
System.out.println(r.getRandom());
}
}
}

modify this to your needs...
if this was not the problem then please clarify more to us...
regards
maulin

[Maulin Vasavada]

hi
sorry in creating constructor in main i swapped two arguments
it should be random(min,max) ..
regards
maulin

[Hassan Marzooq]

HELLO.
Exactly for the same code i was looking for.But i am amazed that why any author didn't mention the same technique.Anyway, thanks for sharing code.
Best Regards,
Hassan.

[joyce ann casayuran]

i found this code on the web.
and i think this is also a greate Random class

  
public class MyRandom {
   // Return a random double in [0,1).
   public static double dblRandom() {
      return Math.random();
   }
   // Return a random double in [0,high).
   public static double dblRandom(double high) {
      return Math.random()*high;
   }
   // Return a random double in [low,high).
   public static double dblRandom(double low, double high) {
      return Math.random()*(high - low) + low;
   }
   // Return a random integer from low to high (inclusive).
   public static int intRandom(int low, int high) {
      int nb = high - low + 1;
      return (int)(Math.random()*nb + low);
   }
   // Return a random integer from 1 to n inclusive.
   public static int intRandom(int n) {
      return (int)(Math.random()*n + 1);
   }
   // Return a random bit (0 or 1).
   public static int bitRandom() {
      return (int)(Math.random()*2);
   }
   // Return a random boolean (false or true).
   public static boolean boolRandom() {
      return Math.random() >= 0.5;
   }
}

hope this will help

[Jim Yingst]

Note that the code given by Maulin will never return the specified maximum value, because the number returned by Math.random() will always be less than 1, and int arithmetic rounds down for positive numbers. E.g. if min is 1 and max is 6, the largest value you might see is 5.999999... - but when you round it to an int, it's 5, not 6.
The intRandom(low, high) method shown by Joyce is correct - it has an extra +1 which makes the necessary difference.
[ December 23, 2002: Message edited by: Jim Yingst ]

[Peter den Haan]

new java.util.Random().nextInt(max - min + 1) + min;

- Peter

[Maulin Vasavada]

hi all,
of course i meant it to be the way it is. it won't return MAX number anytime. i just shifted the range from [0.0,1.0) to [min,max)
once basics works then grooming doesn't take much time
thanks for pointing that out.
regards
maulin