Re: Please review this code

From:

markspace <nospam@nowhere.com>

Newsgroups:

comp.lang.java.programmer

Date:

Wed, 19 Aug 2009 12:46:06 -0700

Message-ID:

<h6hkq5$avu$1@news.eternal-september.org>

guptan wrote:

My problem is sometimes the getRandom(int low, int high) function
returns negative values.
Please review this code

import java.util.Random;

public class RNG
{
    private Random random;

    public RNG() {
        if(random == null){
            random = new Random(System.currentTimeMillis());
        }
         random.setSeed(System.currentTimeMillis());

As others have mentioned, the Random class already does this, so why
make another class? I'd just use some static methods.

public class MyMathUtils {

   // makes this class static only, final
   private MyMathUtils() {}

   // Thread-safe lazy initialization
   private static class LazyRandomHolder {
     static final Random INSTANCE = new Random();
   }

   public static int getRandom( int max ) {
     return LazyRandomHolder.INSTANCE.nextInt( max );
   }

   public static int getRandom( int a, int b ) {
     if( a > b ) {
       int temp = a;
       a = b;
       b = temp;
     } else if( a == b )
       return a;
     long range = (long)b - a + 1;
     return a + (int)(LazyRandomHolder.INSTANCE.nextDouble()*range);
   }
}

Not tested!