Java Random create random String example 4

import java.util.Random; 

public class Main{ 
    private static final String dCase = "abcdefghijklmnopqrstuvwxyz"; 
    private static final String uCase = "ABCDEFGHIJKLMNOPQRSTUVWXYZ"; 
    private static final String sChar = "!@#$%^&*"; 
    private static final String intChar = "0123456789"; 
    private static Random r = new Random(); 
    private static String pass = ""; 

    public static void main (String[] args) { 
        while (pass.length ()  != 16){ 
            int rPick = r.nextInt(4); 
            if (rPick == 0){ 
                int spot = r.nextInt(25); 
                pass += dCase.charAt(spot); 
            } else if (rPick == 1) { 
                int spot = r.nextInt (25); 
                pass += uCase.charAt(spot); 
            } else if (rPick == 2) { 
                int spot = r.nextInt (7); 
                pass += sChar.charAt(spot); 
            } else if (rPick == 3){ 
                int spot = r.nextInt (9); 
                pass += intChar.charAt (spot); 
            } /*from w  w w .  j  av a2 s  .  c o  m*/
        } 
        System.out.println ("Generated Pass: " + pass); 
    } 
}