package Others;

import java.util.Collections;
import java.util.Random;
import java.util.List;
import java.util.ArrayList;


/**
 * Creates a random password from ASCII letters
 * Given password length bounds
 *
 * @author AKS1996
 * @date 2017年10月25日
 */
class PasswordGen {
 public static void main(String args[]) {
 String password = generatePassword(8, 16);
 System.out.print("Password: " + password);
 }

 static String generatePassword(int min_length, int max_length) {
 Random random = new Random();

 String upper = "ABCDEFGHIJKLMNOPQRSTUVWXYZ";
 String lower = "abcdefghijklmnopqrstuvwxyz";
 String numbers = "0123456789";
 String specialChars = "!@#$%^&*(){}?";

 String allChars = upper + lower + numbers + specialChars;

 List<Character> letters = new ArrayList<Character>();
 for (char c : allChars.toCharArray())
 letters.add(c);

 // Inbuilt method to randomly shuffle a elements of a list
 Collections.shuffle(letters);
 StringBuilder password = new StringBuilder();

 // Note that size of the password is also random
 for (int i = random.nextInt(max_length - min_length) + min_length; i > 0; --i) {
 password .append( letters.get(random.nextInt(letters.size())));
 }

 return password.toString();
 }
}