Math.random() really quite good

I am just writing some stuff in Java and I had to be shure that Math.random() was quite random. You never know with thees random methods. So here some gnuplot output of 200000 and 20000 runs.



And here is a little program where you can creatre a random String or StringBuffer with just characters.

 1 public class helloworld {
 2 
 3     /**
 4      * Just runs the method. If a arg is given with that if not with 16 chars
 5      */
 6     public static void main(String[] args) {
 7             System.out.println(getRand((args.length > 0)
 4                                  ? (Integer.parseInt(args[0])) : 16));
 9     }
10 
11     /**
12      * Return a random string
13      *
14      * @param how long the string should be
15      * @return the string could be a StringBuffer for performace
16      */
17     public static String getRand(int howLong){
18         /* Use string buffer as String+= is very slow */
19         /* Read Effective Java by Bloch, Josh*/
20         StringBuffer returnBuffer = new StringBuffer();
21         for (int i = 0; i < howLong ; i++) {
22             returnBuffer.append ((char) (Math.random() * 26 + 'a'));
23         }
24         return returnBuffer.toString();
25     }
26 }
27 

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