public Calculator() {
	setTitle("Rechner");
	TextField hex = new TextField(), dec = new TextField(), bin = new TextField();
	Label text[] = new Label[] { new Label("Dezimal: "), new Label("Hex: "), new Label("Biner: ") };
	Button key = new Button("Umrechnen");

	setLayout(new GridLayout(4, 2));
	add(text[0]);
	add(dec);
	add(text[1]);
	add(hex);
	add(text[2]);
	add(bin);
	add(key);

	this.addWindowListener(this);
	dec.addActionListener(this);
	hex.addActionListener(this);
	bin.addActionListener(this);
	key.addActionListener(this);
	setVisible(true);
	setSize(250, 150);
	setLocation(150, 150);
    }