[java] Masking password input from the console : Java

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...

If you're dealing with a Java character array (such as password characters that you read from the console), you can convert it to a JRuby string with the following Ruby code:

# GIST: "pw_from_console.rb" under "https://gist.github.com/drhuffman12"

jconsole = Java::java.lang.System.console()
password = jconsole.readPassword()
ruby_string = ''
password.to_a.each {|c| ruby_string << c.chr}

# .. do something with 'password' variable ..    
puts "password_chars: #{password_chars.inspect}"
puts "password_string: #{password_string}"

See also "https://stackoverflow.com/a/27628738/4390019" and "https://stackoverflow.com/a/27628756/4390019"

Console console = System.console();
String username = console.readLine("Username: ");
char[] password = console.readPassword("Password: ");

You would use the Console class

char[] password = console.readPassword("Enter password");  
Arrays.fill(password, ' ');

By executing readPassword echoing is disabled. Also after the password is validated it is best to overwrite any values in the array.

If you run this from an ide it will fail, please see this explanation for a thorough answer: Explained

The given code given will work absolutely fine if we run from console. and there is no package name in the class

You have to make sure where you have your ".class" file. because, if package name is given for the class, you have to make sure to keep the ".class" file inside the specified folder. For example, my package name is "src.main.code" , I have to create a code folder,inside main folder, inside src folder and put Test.class in code folder. then it will work perfectly.