Question

Introduction:

One of the advantages of using Loops is to reduce the amount of programming effort especially when repeating the code is required. To demonstrate this advantages, the code below shows the PasswordGeneration class. The purpose of this program is to generate an ad hoc 12 letters long password upon a selection of a character from a string that contains a pool of letters.

/*simple Java program that generate a 12 characters long passwords * author : Dr. Modafar Ati * Version 1.0 */ public class PasswordGeneration {        public static void main(String[] args) {                        String password;               //create a pool of letters               String letters = new String("&*()789FGHIJKabcdefghijklmLMNO^|{]}PQRSTU!@#$%VWXYZ123456nopqrstuvwxyzABCDE");               //select 12 random characters from the above pool               char c1 = letters.charAt((int)(Math.random()*letters.length()));               char c2 = letters.charAt((int)(Math.random()*letters.length()));               char c3 = letters.charAt((int)(Math.random()*letters.length()));               char c4 = letters.charAt((int)(Math.random()*letters.length()));               char c5 = letters.charAt((int)(Math.random()*letters.length()));               char c6 = letters.charAt((int)(Math.random()*letters.length()));               char c7 = letters.charAt((int)(Math.random()*letters.length()));               char c8 = letters.charAt((int)(Math.random()*letters.length()));               char c9 = letters.charAt((int)(Math.random()*letters.length()));               char c10 = letters.charAt((int)(Math.random()*letters.length()));               char c11 = letters.charAt((int)(Math.random()*letters.length()));               char c12 = letters.charAt((int)(Math.random()*letters.length()));                             // Combine all characters into a string that represent the generated password               password = Character.toString(c1) +Character.toString(c2) + Character.toString(c3);               password += Character.toString(c4) +Character.toString(c5) + Character.toString(c6);               password += Character.toString(c7) +Character.toString(c8) + Character.toString(c9);               password += Character.toString(c10) +Character.toString(c11) + Character.toString(c12);                             //present the user with the generated password               System.out.println("Password generetad is : " +password);        } }

Now upon implementing Loops strategy, the number of lines of the previous program will be reduced significantly. Version 2 of the above code can be written after adding more functionality to it is shown below. The new code has extra flexibility added to it by given the user to specify the size of the password required.

/*simple Java program that generate a flexible size passwords * author : Dr. Modafar Ati * Version 2.0 */ import java.util.Scanner; public class PasswordGeneration {        public static void main(String[] args) {               Scanner input = new Scanner(System.in);               String password="";               char c;               int size = 0;               String letters = new String("&*()789FGHIJKabcdefghijklmLMNO^|{]}PQRSTU!@#$%VWXYZ123456nopqrstuvwxyzABCDE");               System.out.print("What is the length of password would you like to generate : ");               int lengthOfPasswords =input.nextInt();                                    while(size < lengthOfPasswords) {                            //select a random character from the list                            c = letters.charAt((int)(Math.random()*letters.length()));                                                       //now append the letter to the pass String                            password += Character.toString(c);                                                       size++;               }               System.out.println(password);               input.close();        } }

Task:

You are required to modify the second version of the program to satisfy the following conditions:

1. Create a second string that contains your full id and full name.
2. The program should select from both the original string and the string created that contains your id and name generated in 1 above.
3. Size of the password should not exceed 18 letters long
4. The program should allow the user to specify the number of passwords to be generated
5. The program should allow the user to run the program as many times as he/she require by prompting the user need to generate a number of passwords again.

PS: Below is a sample output of the program

How many passwords would like to generate : 5 What is the length of password would you like to generate : 15 The following 5 are now generated ________________________________________________________________ tE3gEZMSEHtA6Ku n%iPfc%JGZaxGk6 Z^Rhdz5f7OIVx2F jh3dldFfFO9W)kS Kpjn$]9Pmpm(bX3 Would you like to generate another set of passwords (Y/N ) : y How many passwords would like to generate : 10 What is the length of password would you like to generate : 10 The following 10 are now generated ________________________________________________________________ &^upcN&DvY *x^D2(tX}$ Ie9HjCCIkD oOr*mT{kpC 4H7cz$m2U$ (]BBIRykgW *V8vTh2DN& BMxw%W8*|v dyLivkl)U1 hP4eFeI5FM Would you like to generate another set of passwords (Y/N ) : N                      Thank you

Notes :

1. Lab is worth 5% of total mark
2. Submission of the lab is no later than Thursday 31^st October 2020 @ 18:00
3. No submission allowed after the deadline
4. Any submission via email or after deadline will not be accepted
5. This lab is individual work
6. You are required to submit your soft copy of your java code file via Blackboard
7. You are required to submit a document showing screenshots of the output
8. Failing to submit any of the above will cause reduction of 50% of the mark

Answer 1

Here is the working code. Can be tweaked if required. I've added comments wherever necessary

import java.util.Scanner;

public class PasswordGeneration {

        public static void main(String[] args) {
                Scanner input = new Scanner(System.in);
                String password;
                int size;
                char c;
                String choice;
                
                String letters = new String("&*()789FGHIJKabcdefghijklmLMNO^|{]}PQRSTU!@#$%VWXYZ123456nopqrstuvwxyzABCDE");
                //New String, Replace with student mail and student name
                String nameAndEmail = "[email protected]";
                
                //do-while loop to execute whole program as long as user wants
                do {
                        System.out.print("How many passwords would like to generate : ");
                        int numberOfPassword = input.nextInt();
                        
                        System.out.print("What is the length of password would you like to generate : ");
                        int lengthOfPasswords;
                        
                        //take valid input from user
                        do {
                                lengthOfPasswords = input.nextInt();
                                if(lengthOfPasswords>18) {
                                        System.out.println("Lenth of password cannot be greater than 18 characters.");
                                        System.out.print("What is the length of password would you like to generate : ");
                                }
                        }while(lengthOfPasswords>18);
                        
                        System.out.println("The following " + numberOfPassword + " are now generated \n");
                        System.out.println("-----------------------------------------------------------------");
                        
            //to generate multiple passwords as per users requirement
                        for(int i=0; i<numberOfPassword; i++) {
                                password="";
                                size = 0;
                                while(size < lengthOfPasswords) {
                                        //When value of size is even, select a character from 'letters' String, otherwise select from 'nameAndEmail' String
                                        if(size%2==0) {
                                                //select a random character from the String letters
                                                c = letters.charAt((int)(Math.random()*letters.length()));
                                        }else {
                                                //select a random character from the String nameAndEmail
                                                c = nameAndEmail.charAt((int)(Math.random()*nameAndEmail.length()));
                                        }

                                        //now append the letter to the pass String
                                        password += Character.toString(c);
                                        size++;
                                }

                                System.out.println(password);
                        }
                        
                        System.out.print("Would you like to generate another set of passwords (Y/N ) : ");
                        input.nextLine(); //dummy input to empty the input buffer
                        choice = input.nextLine();
                }while(choice.equalsIgnoreCase("Y"));
                //to format output spacing
                System.out.printf("%20s", "Thank You");
                
                input.close();
        }

}

Output: