PasswordValidaton.java

package ExceptionHandling;

import java.util.Scanner;


class InvalidPasswordException extends Exception {
    public InvalidPasswordException(String message) {
        super(message);
    }
}

public class PasswordValidaton {
    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);
        String password;

        try {
            System.out.print("Enter your password: ");
            password = sc.nextLine();


            if (password == null) {
                throw new NullPointerException("Password is empty");
            }


            if (!isValidPassword(password)) {
                throw new InvalidPasswordException("Password is invalid: Must be at least 8 characters and include a \n" +
                        "digit.");
            }


            System.out.println("Password accepted. Registration successful.");

        } catch (InvalidPasswordException e) {
            System.out.println(e.getMessage());
        } catch (NullPointerException e) {
            System.out.println("NullPointerException");
        }
    }


    public static boolean isValidPassword(String password) {
        if (password.length() < 8) return false;
        for (char c : password.toCharArray()) {
            if (Character.isDigit(c)) return true;
        }
        return false;
    }
}