How to generate a random alpha numeric String in java.

package com.digit;

import java.util.Date;

import java.util.Random;

public class RandumString {

public static void main(String args[]){

//Randum ren= new Randum();

String a = Randum.generateRandomString(6);

System.out.println(a);

}

}

class Randum{

private static Random random = new Random((new Date()).getTime());

    public static String generateRandomString(int length) {

      char[] values = {'a','b','c','d','e','f','g','h','i','j',

               'k','l','m','n','o','p','q','r','s','t',

               'u','v','w','x','y','z','0','1','2','3',

               '4','5','6','7','8','9'};

      String out = "";

      for (int i=0;i<length;i++) {

          int idx=random.nextInt(values.length);

        out += values[idx];

      }

      return out;

    }

}