# Generate a random number?

• 09-13-2012, 06:19 PM
NDF
Generate a random number?
I'm trying to generate a random number in Java.

I need one number to be between 5.00-20.00 (going by intervals of 5.01, 5.02, 5.03, etc)
I also need the same thing between 1.00-5.00.

How would I go about doing this?
• 09-13-2012, 09:30 PM
Fou-Lu
I don't believe there is an existing built in class to find random between two specific numbers.
One can be easily written though, by basing off of the min and max provided.
PHP Code:

``` public static double randBetween(double dMin, double dMax){    // either extend Random and call to this, or make random.  I'll make random here    Random r = new Random();    return dMin + (r.nextDouble() * (dMax - dMin));}  ```
Done and done.

To format to two decimal places, you may use the printf:
PHP Code:

``` System.out.printf("%.2f\n", randBetween(5.0, 20));  ```
Or mathematically calculate it by cast, multiply and divide:
PHP Code:

``` double d = randBetween(5, 20);d = ((double)(int)(d * 100)) / 100;  ```