I think what you need to do is provide implementation for the method stubs that are contained within the KeyListener interface by adding ;'s. You are better off just extending the KeyAdapter class which implements the KeyListener class.
Code:
public void KeyTyped(KeyEvent input) {
char key = input.getKeyChar();
keyLabel.setText("You pressed " + key);
}

public void keyPressed(KeyEvent txt) {;}

public void keyReleased(KeyEvent txt) {;}