Java-Code

import java.util.regex.Pattern;

import javax.swing.JOptionPane;

public class Program
{
	private static final String masterLockString = "10011011";
	private static int masterLockInt = Integer.parseInt(masterLockString, 2);

	public static void main(String[] args)
	{
		String playerKey = "";
		boolean keyIsCorrect = false;
		int guessKeyCounter = 0;

		while (!keyIsCorrect)
		{
			guessKeyCounter++;
			
			playerKey = JOptionPane.showInputDialog("Guess " + guessKeyCounter + "\n\nEnter your 8-Bit key: ");

			if (checkKey(playerKey))
			{
				keyIsCorrect = compareKey(playerKey);
			}
		}

		JOptionPane.showMessageDialog(null, "'" + playerKey + "' is the right key!\n\nYou have " + guessKeyCounter + " attempts required.",
				"YOU WON", JOptionPane.INFORMATION_MESSAGE);
	}

	private static boolean checkKey(String playerKey)
	{
		if (playerKey.length() != 8)
		{
			JOptionPane.showMessageDialog(null, "Your key has not 8 bits!", "WRONG KEY", JOptionPane.ERROR_MESSAGE);
			return false;
		}

		if (!Pattern.matches("[01]*", playerKey))
		{
			JOptionPane.showMessageDialog(null, "Your key is not binary!", "WRONG KEY", JOptionPane.ERROR_MESSAGE);
			return false;
		}

		return true;
	}

	private static boolean compareKey(String playerKey)
	{
		int parsedKey = Integer.parseInt(playerKey, 2);
		int exclusiveOrResult = masterLockInt ^ parsedKey;

		if (exclusiveOrResult == 0)
		{
			return true;
		}

		String resultString = Integer.toBinaryString(exclusiveOrResult);

		int matches = 8 - resultString.length();

		for (int i = 0; i < resultString.length(); i++)
		{
			if (resultString.charAt(i) == '0')
			{
				matches++;
			}
		}

		JOptionPane.showMessageDialog(null, "Your key:\t" + playerKey + "\n\nCorrect bits:\t" + matches, "RESULT\n",
				JOptionPane.INFORMATION_MESSAGE);

		return false;
	}
}