schoolstuff

        // attach listeners to each of the buttons and the key text field
        //      use lambda expressions
        encrypt.addActionListener( e -> output.setText(secrets.encrypt(key.getText(), msg.getText())) );
        decrypt.addActionListener( e -> output.setText(secrets.decrypt(key.getText(), msg.getText())) );
        key.addActionListener( e -> {
            if (secrets.getState() == Secrets.State.LOCKED) {
              secrets.unlock(key.getText());
              output.setText(secrets.getMessage());
            }
        } );
        buttonA.addActionListener( e -> {
          secrets.unlock(buttonA.getText());
          output.setText(secrets.getMessage());
        } );
        buttonB.addActionListener( e -> {
          secrets.unlock(buttonB.getText());
          output.setText(secrets.getMessage());
        } );
        buttonC.addActionListener( e -> {
          secrets.unlock(buttonC.getText());
          output.setText(secrets.getMessage());
        } );