Input Password Function in Console Using Java

Letting users picking password in console is a commonly wanted feature. We let the users enter a password string, and check if it is a valid password e.g. minimal length 6 – and then asking users to confirm it again.

The following PasswordUtils provide a static method inputPasswordTwice that does the above – and return the password if password string is valid and confirmed.

package helloacm.com

import java.util.Scanner;

class PasswordUtils {
    public static boolean passwordValid(String pass) {
        return pass.length() >= 6;
    }

    public static String inputPassword() {
        Scanner in = null;
        String password;
        var cons = System.console();
        if (cons == null) {
            in = new Scanner(System.in);
        }
        while (true) {
            if (cons != null) {
                var pwd = cons.readPassword("password: ");
                password = String.valueOf(pwd);
            } else {
                var input = in.nextLine().trim();
                password = input.split("\\s+")[0];
            }
            if (passwordValid(password)) {
                return password;
            }
            System.out.println("Invalid password, please input again.");
        }
    }

    public static String inputPasswordTwice() {
        String password0;
        while (true) {
            System.out.println("Please input password.");
            password0 = inputPassword();
            System.out.println("Please input password again.");
            var password1 = inputPassword();
            if (password0.equals(password1)) {
                break;
            }
            System.out.println("Two passwords do not match, please input again.");
        }
        return password0;
    }
}

public class Main {
    public static void main(String[] args) {
        var pass = PasswordUtils.inputPasswordTwice();
        System.out.println(pass);
    }
}

We prefer to use the System.console.readPassword if it is available, otherwise, the Scanner with System.in is used instead.

–EOF (The Ultimate Computing & Technology Blog) —