Question

i need know how Write a program that tests whether a string is a valid password. The password rules are:

• It must have at least eight characters.
• It must contain letters AND numbers
• It must contain at least two digits
• It must contain an underscore (_)

Write a program that prompts the user to enter a password and displays the password entered and whether it is valid or invalid.

Answer 1

If you have any problem with the code feel free to comment.

Program

import java.util.Scanner;

public class Test {
   public static void main(String[] args) {
       Scanner sc = new Scanner(System.in);
       System.out.print("Enter the password: ");
       String pass = sc.nextLine();
       System.out.println(pass+" is valid? "+checkPassword(pass));
      
      
       /*Test cases for code verfication*/
//       System.out.println("asdzx_12 is valid? "+checkPassword("asdzx_12"));
//       System.out.println("asdzxs_1a is valid? "+checkPassword("asdzxs_1a"));
//       System.out.println("johnw_7_ is valid? "+checkPassword("johnw_7_"));
      
       sc.close();
      
   }
  
   public static boolean checkPassword(String pass) {
       int digits=0, letters=0, underscore=0;
       char[] ch = pass.toCharArray();
      
       if(pass.length()<8)//return falses if length is less than 8
           return false;
       else {
          
           for(int i=0; i< ch.length; i++) {
               //checking number of letters, digits and underscore
               if(Character.isDigit(ch[i]))
                   digits++;
               if(Character.isLetter(ch[i]))
                   letters++;
               if(ch[i] == '_')
                   underscore++;
           }
           //validating password
           if(letters>0 && digits>=2 && underscore==1)
               return true;
           else
               return false;
       }
      
   }
}

Output