Problem java.langNullPointerException

String guessAsString = console.readLine("Enter a letter: ");

import java.io.Console;

public class mainHangman {

    public static void main(String[] args) {

        GameHangman       game       = new GameHangman("treehouse");
         PrompterHangman prompter = new PrompterHangman(game);

        boolean isHit = prompter.promptForGuess();

        if (isHit) {
            System.out.println("We got a hit");
        } else {
            System.out.println("That was a miss");
        }
    }
}

import java.io.Console;

public class PrompterHangman {

    private GameHangman mGame;

    public PrompterHangman(GameHangman game) {
        mGame = game;
    }

    public boolean promptForGuess() {

        Console console = System.console();

        String guessAsString = console.readLine("Enter a letter: ");
        char    guess               = guessAsString.charAt(0);

        return mGame.applyGuess(guess);
    }
}

public class GameHangman {

    private String mAnswer;
    private String mHits;
    private String mMisses;

    public GameHangman(String answer) {
        mAnswer = answer;
        mHits   = "";
        mMisses = "";
    }

    public boolean applyGuess(char letter) {

        boolean isHit = mAnswer.indexOf(letter) >= 0;
        if (isHit) mHits   += letter;
        else       mMisses += letter;
        return  isHit;
    }
}