Question

I have attempted to implement some changes to my source code and was unable to succefully implement there are (two) changes. I am in the learning process so comments help in the learning curve so if possible leave comments.

PLEASE DONT CHANGE ANY OF THE SOURCE CODE - unless needed to implement the changes.

* Change the program so that the user can choose to either check if a password is valid or have the program randomly generate a password that is valid.

* Add the functionality to generate a valid password, display this password and end the program.

SOURCE CODE PROVIDED BELOW

import java.util.Scanner;

public class PasswordChecker {

   public static void main(String[] args) {
      
       Scanner keyboard = new Scanner(System.in);
       String password;
       int uppers = 0;
       int lowers = 0;
       int numbers = 0;
       int special = 0;
       int length = 0;
      
       System.out.println("Enter your password: ");
       System.out.println("Rules: ");
       System.out.println("* 9 to 30 characters in length");
       System.out.println("* contain at least one uppercase letter (A - Z)");
       System.out.println("* contain at least one lowercase letter (a - z)");
       System.out.println("* contain at least one number digit (0 - 9)");
       System.out.println("* contain at least one special character (# @ $ % + = )");
       password = keyboard.nextLine();
      
      
       length = password.length();
       if ((length < 9) || (length > 30)) {
           System.out.println("Please re-enter password, keep in mind more than 9 char and less than 30");
       }
       else
       {
           for(int i = 0; i < length; i++) {
      
               if(Character.isUpperCase(password.charAt(i)))
                   uppers++;
          
               else if (Character.isLowerCase(password.charAt(i)))
                   lowers++;
          
               else if (Character.isDigit(password.charAt(i)))
                   numbers++;
              
               else if (specialCompare(password.charAt(i)))
                   special++;
              
           }  
       }
      
       if((uppers == 0) || (lowers == 0) || (numbers == 0) || (special == 0))
           System.out.println("Password is missing one of the requirements");
       else
           System.out.println("Good password");
   }//End main  
  
   static boolean specialCompare(char a) {
       switch(a) {
       case '@':
       case '#':
       case '$':
       case '%':
       case '+':
       case '=':
           return true;
       }
       return false;
   }//End specialCompare

}//End class

Answer 1

//All the code in bold is the code added by me

import java.util.*;

public class PasswordChecker
{

public static void main (String[]args)
{

Scanner keyboard = new Scanner (System.in);
String password;
int uppers = 0;
int lowers = 0;
int numbers = 0;
int special = 0;
int length = 0;
int choice = 0;

System.out.println ("press 1 to enter your own password.");
System.out.println ("press 2 to get an auto generated password.");
choice = keyboard.nextInt ();
if (choice == 1)
{

System.out.println ("Enter your password: ");
System.out.println ("Rules: ");
System.out.println ("* 9 to 30 characters in length");
System.out.println ("* contain at least one uppercase letter (A - Z)");
System.out.println ("* contain at least one lowercase letter (a - z)");
System.out.println ("* contain at least one number digit (0 - 9)");
System.out.println ("* contain at least one special character (# @ $ % + = )");
password = keyboard.nextLine ();

length = password.length ();
if ((length < 9) || (length > 30)) System.out.println("Please re-enter password, keep in mind more than 9 char and less than 30");
else
{

for (int i = 0; i < length; i++)
{

if (Character.isUpperCase (password.charAt (i))) uppers++;

else if (Character.isLowerCase (password.charAt (i))) lowers++;

else if (Character.isDigit (password.charAt (i))) numbers++;

else if (specialCompare (password.charAt (i))) special++;

}

}

if ((uppers == 0) || (lowers == 0) || (numbers == 0) || (special == 0)) System.out.println ("Password is missing one of the requirements");
else System.out.println ("Good password");

} //End is x==1
else if (choice == 2)
{

//If x==2 we will auto generate pass word

password = "";
int x = 0;
int count = 0;

length = getRandomInRange (9, 30); // here we randomly decide length of our password
for (int i = 0; i < length; i++) // In this loop we generate each and every character of password randomly
{

if (count < 4 && (length - i - 1) == (4 - count))
{

//this if ensures if each of number, special character, lowercase and uppercase is taken atleast once

if (uppers == 0)
{

password += getUpperCase ();
count++;
uppers++;

}
else if (lowers == 0)
{

password += getLowerCase ();
count++;
lowers++;

}
else if (numbers == 0)
{

password += getNumber ();
count++;
numbers++;

}
else
{

password += getSpecialCharacter ();
count++;
special++;

}

continue;

}

x = getRandomInRange (1, 4);

//Below if else ladder decides which of the four available cases to use as our next character in password.
if (x == 1) //for uppercase
{

password += getUpperCase ();
if (uppers == 0) count++;
uppers++;

}
else if (x == 2) //for lowercase
{

password += getLowerCase ();
if (lowers == 0) count++;
lowers++;

}
else if (x == 3) //for number
{

password += getNumber ();
if (numbers == 0) count++;
numbers++;

}
else //for special character
{

password += getSpecialCharacter ();
if (special == 0) count++;
special++;

}

}
System.out.println(password);

} // End if x == 2
else System.out.println (choice + " is an invalid choice. Exiting.....");

} //End Main

public static char getUpperCase () //this function will get a random uppercase character
{

return (char) getRandomInRange (65, 90);

}

public static char getLowerCase () //this function will get a random lowercase character
{

return (char) getRandomInRange (97, 122);

}

public static int getNumber () //this function will get a random number between 0 - 9
{

return getRandomInRange (0, 9);

}

public static char getSpecialCharacter () //this function will get a random special character
{

int x = getRandomInRange (1, 6);
switch (x)
{

case 1:
return '@';
case 2:
return '#';
case 3:
return '$';
case 4:
return '%';
case 5:
return '+';
case 6:
return '=';

}

return '@';

}

public static int getRandomInRange (int min, int max) //this function will generate a random in the given range.
{

Random r = new Random ();
return r.nextInt ((max - min) + 1) + min;

}

static boolean specialCompare (char a)
{
switch (a)
{
case '@':
case '#':
case '$':
case '%':
case '+':
case '=':
   return true;
}
return false;
}               //End specialCompare
}

OUTPUT:-