generate random chracter ASCII

sy lumyan bingung pas ada si suruh bwt pemangkitan niali random untuk karakter ASCII, mana pake bahasa java lgi ...lumayan bingung tapi setelah cari-cari referensi dari mbah google akhirnya dapet juga...di bawah ni ada contoh source program  generate random chracter ASCII, pake bahasa program java..mudah mudahan dapet membantu temen-temen y......aplikasinya untuk pembentukan Password..


import java.util.Scanner;
import java.util.Random;
import java.lang.*;
import java.nio.charset.*;
import java.util.Arrays;

public class passwords {

   public static void main(String[] args)
  
   {

      
 Scanner in = new Scanner(System.in);     
 
 

 
 int userSelection;     
 int userLength;     
 int randNum;
 int randNum2;
 int randNum3;
 int randNum4;
        
        
System.out.println("                Password Generator Menu               ");
System.out.println();
System.out.println("******************************************************");
System.out.println("* [1] Lowercase Letters                              *");
System.out.println("* [2] Lowercase & Uppercase Letters                  *");
System.out.println("* [3] Lowercase, Uppercase, and Numbers              *");
System.out.println("* [4] Lowercase, Uppercase, Numbers, and Punctuation *");     
System.out.println("* [5] Quit                                           *");
System.out.println("******************************************************");
System.out.println();   
System.out.print("Enter Selection (1-5): ");
userSelection = in.nextInt(); 
if (userSelection == 5)
{
System.out.println();
System.exit(0);
}    
System.out.println();
System.out.print("Password Length (1-128): ");
userLength = in.nextInt();   
System.out.println();


if (userSelection == 1)
{
System.out.print("Password: ");
randNum2 = (int)((Math.random() * 26) + 97);

for(int i=0; i<userLength; i++){
                randNum2 = (int)((Math.random() * 26) + 97);
               System.out.print((char)randNum2);
          }
}

if (userSelection == 2)
{
    System.out.print("Password: ");

for(int i=0; i<userLength; i++){
    randNum2 = (int)((Math.random() * 52) + 65);
   
        if (randNum2 >= 91)
            {
               
                System.out.print((char)(randNum2 + 7));
            }
               
           
               System.out.print((char)randNum2);
          }
   
}

if (userSelection == 3)
{
    System.out.print("Password: ");
randNum2 = (int)((Math.random() * 9) + 48);

for(int i = 0; i<userLength; i++){
                randNum2 = (int)((Math.random() * 9) + 48);
               System.out.print((char)randNum2);
          }   
   
}

if (userSelection == 4)
{
    System.out.print("Password: ");
randNum2 = (int)((Math.random() * 88) + 33);

for(int i=0; i<userLength; i++){
                randNum2 = (int)((Math.random() * 88) + 33);
               System.out.print((char)randNum2);
          }   
       
}
System.out.println();
             
}
}

link:
http://www.java-forums.org/new-java/24004-randomly-generate-range-ascii-characters.html