Question

How to mask a password from console input? I’m using Java 6.

I’ve tried using console.readPassword(), but it wouldn’t work. A full example might help me actually.

Here’s my code:

import java.io.BufferedReader;
import java.io.Console;
import java.io.IOException;
import java.io.InputStreamReader;

public class Test 
{   
    public static void main(String[] args) 
    {   
        Console console = System.console();

        console.printf("Please enter your username: ");
        String username = console.readLine();
        console.printf(username + "\n");

        console.printf("Please enter your password: ");
        char[] passwordChars = console.readPassword();
        String passwordString = new String(passwordChars);

        console.printf(passwordString + "\n");
    }
}

I’m getting a NullPointerException…

Answer 1

A full example ?. Run this code : (NB: This example is best run in the console and not from within an IDE, since the System.console() method might return null in that case.)

import java.io.Console;
public class Main {

    public void passwordExample() {        
        Console console = System.console();
        if (console == null) {
            System.out.println("Couldn't get Console instance");
            System.exit(0);
        }

        console.printf("Testing password%n");
        char[] passwordArray = console.readPassword("Enter your secret password: ");
        console.printf("Password entered was: %s%n", new String(passwordArray));

    }

    public static void main(String[] args) {
        new Main().passwordExample();
    }
}