Question

Password Validation

Write a program called PasswordValidationYourLastName that validates a new password, following these guidelines:

• Must be at least 8 characters
• Must have at least 1 uppercase letter
• Must have at least 1 lowercase letter
• Must have at least 1 digit

Write a program that asks for a password, and then asks again to confirm it (you can use the scanner or JOptionPane). Pass those two Strings to a method called validatePassword( ). Your validatePassword( ) should return a boolean - true if the passwords pass validation and false if the passwords do not pass validation.

If the passwords don’t meet validation rules, prompt again. If the passwords meet validation rules, return “Password changed” and exit the program.

Your validatePassword( ) method will check to see if the two passwords passed in are valid. All of the checks should happen in the method.

Right off the bat in your method, you should automatically return false if the passwords are not the same.

Again, if they are less than 8, then you can immediately return false too.

If the passwords are the same, then begin your checks listed above. You could use booleans variables as flags to keep track whether you've found an uppercase, lowercase and digit.

You can use isUpperCase(), isLowerCase(), isDigit() to check to see if something is a digit, uppercase or lowercase in the String.

After looking at the string, if all of your boolean variables are true (meaning you've found them), then you know your passwords are good.

Is there a reason to compare both passwords if they are the same? No. So just run your checks through one variable.

Again: use a boolean as your return type in the method. If any of the components are not met, change the boolean to false. Once the boolean is set to false, you know the password was not valid and you can return that to your main method as false for the re-prompting to happen again (probably in a loop of some kind).

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Answer 1

Java code

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package hello;

import java.util.Scanner;

public class PasswordValidationYourLastName {

   static boolean validatePassword(String s1,String s2)
   {
       boolean isUpper=true,isLower=true,isNum=true;
       String upperCaseChars = "(.*[A-Z].*)";
       String lowerCaseChars = "(.*[a-z].*)";
       String numbers = "(.*[0-9].*)";
      
       if(s1.equals(s2)==false)
       {
           System.out.println("Both password dont match.So try again...");
           return false;
       }
       if(s1.length()<8)
       {
           System.out.println("Password Must be at least 8 characters in length.");
           return false;
       }
       if (!s1.matches(upperCaseChars ))
{
System.out.println("Password should contain atleast one upper case alphabet");
isUpper = false;
}
       if (!s1.matches(lowerCaseChars ))
{
System.out.println("Password should contain atleast one lower case alphabet");
isLower = false;
}
       if (!s1.matches(numbers ))
{
System.out.println("Password should contain atleast one number.");
isNum = false;
}
      
       if(isUpper && isLower && isNum)
           return true;
       else
           return false;
   }
   public static void main(String[] args) {
       // TODO Auto-generated method stub
       Scanner sc=new Scanner(System.in);
       String s1,s2;
       boolean b;
      
       while(true)
       {
           System.out.print("Enter password: ");
           s1=sc.next();
           System.out.print("Confirm your password:");
           s2=sc.next();
           b=validatePassword(s1,s2);
           if(b==true)
           {
               System.out.println("Password changed");
               break;
           }
              
       }
      
   }

}

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Output