generating random characters

        import java.util.*;

       public class Test {

               private static Random rn = new Random();

               private Test()
               {
               }

               public static int rand(int lo, int hi)
               {
                       int n = hi - lo + 1;
                       int i = rn.nextInt() % n;
                       if (i < 0)
                               i = -i;
                       return lo + i;
               }

               public static String randomstring(int lo, int hi)
               {
                       int n = rand(lo, hi);
                       byte b[] = new byte[n];
                       for (int i = 0; i < n; i++)
                               b[i] = (byte)rand('a', 'z');
                       return new String(b, 0);
               }

               public static String randomstring()
               {
                       return randomstring(5, 25);
               }
       }

Actual random numbers are obtained using nextInt(), and then knocked down to the relevant range using the modulo ("%") operator.