Question

Semester 2019

Java Programming Project 3: Loops, Strings, and Character Methods

Having a secure password is a very important practice, particularly when much of our personal information is stored online.

Please write a program that validates a new password, following these 4 rules:

The password must be at least 8 characters long.

The password must have at least one upper case letter.

The password must have at least one lower case letter.

The password must have at least one digit.

1) Your program should ask for a password, and then check first to see if the password is valid (i.e., conforms to the specifications outlined above.) If not, the program should allow the user to continue to enter passwords until s/he enters a valid password.

2) Then your program should confirm the password by requesting that the user enter the password again, and verify that the two match. If they don't match, allow the user to try it again (for a total of 3 tries only).

You will need a minimum of two methods, one to confirm the two passwords, and at least one (or more) to check to see if the password meets the 4 required specifications outlined above.

Carefully examine and follow ALL the program requirements. Make sure you use prologue comments for your program, including prologue comments for each of your methods. You will find both the Java String methods as well as the Character Class Methods immensely helpful for this Lab. Please use comments as well for any part of your code that may not be self-explanatory or may require some additional documentation.

You will find both the Java String methods as well as the Character Class Methods immensely helpful for this Lab.

SUBMISSION GUIDELINES:

1) Please write and submit an algorithm (in class) to help you with the design phase of this lab.

2) Submit a hard copy of your Java program (in class).

3) Attach your java program online in the Assignments tool. Go to Assessments-->Assignment --> Java Programming Project 3.

4) Submit a hard copy of program output or output screen shots of your program in action illustrating its functionality. You should show at least 3 program runs.

Answer 1

// Java program to input two passwords and check if both the passwords match
import java.util.Scanner;

public class PasswordChecker {
  
   // method to return if password is valid or not i.e it follows all the 4 rules
   private static boolean validPassword(String password)
   {
       boolean lengthValid = false, upperValid = false, lowerValid = false, digitValid = false;
       // check if length of password is atleast 8 characters long
       if(password.length() >= 8)
           lengthValid = true;
      
       // loop to check if password contains atleast one lowercase, uppercase and digit
       for(int i=0;i<password.length();i++)
       {
          
           // check if ith character is uppercase
           if(Character.isUpperCase(password.charAt(i)))
               upperValid = true;
           // check if ith character is lowercase  
           else if(Character.isLowerCase(password.charAt(i)))
               lowerValid = true;
           // check if ith character is digit
           else if(Character.isDigit(password.charAt(i)))
               digitValid = true;
       }
      
       // return if the password is valid
       return(lengthValid && upperValid && lowerValid && digitValid);
   }
  
   // method to return if the both passwords match
   private static boolean samePassword(String password, String confirmPassword)
   {
       return(password.equals(confirmPassword));
   }

   public static void main(String[] args) {

       Scanner scan = new Scanner(System.in);
       String password, confirmPassword;
       boolean correctPassword = false;
       // input the password
       System.out.print("Enter password : ");
       password = scan.nextLine();
      
       // loop to validate password and re-prompt until valid
       while(!validPassword(password))
       {
           System.out.println("Invalid password");
           System.out.print("Enter password : ");
           password = scan.nextLine();
       }
      
       // loop to input the passwords again and allow the user 3 tries
       for(int i=0;i<3;i++)
       {
           System.out.print("Enter the password again : ");
           confirmPassword = scan.nextLine();
           // check if password is same
           if(samePassword(password,confirmPassword))
           {
               correctPassword = true;
               break;
           }
       }

       // check if passwords match after 3 tries and display the message accordingly
       if(!correctPassword)
           System.out.println("Both passwords doesn't match");
       else
           System.out.println("Both passwords match");
      
       scan.close();
   }

}
//end of program

Output: