[Java] Wie stell ich andere Farben ein?

import java.awt.*;
import java.awt.event.*;

/**********************************************************
*
* This class implements a simple phone GUI.
* When creating a new object of this class
* the GUI components, such as buttons, labels, etc. are
* just displayed. They do not yet react on user actions,
* such as pressing a button, etc.
*
* @author H. Diethelm, HTA Luzern
* @version 1.0 12-06-2000
* 
**********************************************************/
class JavaPhoneGUI extends Frame {
 
 // Declare and create key buttons
 Button key1 = new Button("1");
 Button key2 = new Button("2");
 Button key3 = new Button("3");
 Button key4 = new Button("4");
 Button key5 = new Button("5");
 Button key6 = new Button("6");
 Button key7 = new Button("7");
 Button key8 = new Button("8");
 Button key9 = new Button("9");
 Button key0 = new Button("0");
 Button keyNo = new Button("#");
 Button keyStar = new Button("*");
 
 // Declare and create other GUI elements
 TextField display = new TextField();
 Button hook = new Button("Hook off");
 Label state = new Label("ready");
 
 // Declare and create panels
 Panel keyPanel = new Panel();
 Panel keyDisplayPanel = new Panel();
 Panel hookStatePanel = new Panel();
 
 
 // Declare listener class for close box of frame
 class CloseListener extends WindowAdapter {
 public void windowClosing(WindowEvent e) {
 System.exit(0);
 }
 }
 // Alternatively you can implement the interface
 // WindowListener. But then every method must be
 // implemented! Also:
 // class CloseListener implements WindowListener { ...
 
 
 class HookListener implements ActionListener {
 // Is called when hook button is pressed
 public void actionPerformed(ActionEvent e) {
 if (e.getActionCommand().equals("Hook off")) {
 hook.setLabel("Hook on");
 state.setText("connected");
 } else {
 hook.setLabel("Hook off");
 state.setText("ready");
 display.setText("");
 }
 }
 }
 
 class KeyListener implements ActionListener {
 // Is called when key button is pressed
 public void actionPerformed(ActionEvent e) {
 if (state.getText().equals("ready")) {
 // Get label of pressed key button and write it to the display
 String no = display.getText() + e.getActionCommand();
 display.setText(no);
 }
 }
 } 


 // Constructor. Assembles and displays the GUI.
 JavaPhoneGUI() {
 // Initialise frame and GUI elements and
 setTitle("JavaPhone");
 setBackground(Color.lightGray);
 setResizable(false);
 display.setEditable(false);
 
 // Add listener objects to GUI elements
 addWindowListener(new CloseListener());
 hook.addActionListener(new HookListener());
 key1.addActionListener(new KeyListener());
 key2.addActionListener(new KeyListener());
 key3.addActionListener(new KeyListener());
 key4.addActionListener(new KeyListener());
 key5.addActionListener(new KeyListener());
 key6.addActionListener(new KeyListener());
 key7.addActionListener(new KeyListener());
 key8.addActionListener(new KeyListener());
 key9.addActionListener(new KeyListener());
 key0.addActionListener(new KeyListener());
 keyNo.addActionListener(new KeyListener());
 keyStar.addActionListener(new KeyListener());
 
 // Set layout of all panels and of frame
 keyPanel.setLayout(new GridLayout(4, 3, 20, 20));
 keyDisplayPanel.setLayout(new BorderLayout(20, 20));
 hookStatePanel.setLayout(new BorderLayout(20, 20));
 setLayout(new BorderLayout(20, 20));
 
 // Add key buttons to key panel
 keyPanel.add(key1);
 keyPanel.add(key2);
 keyPanel.add(key3);
 keyPanel.add(key4);
 keyPanel.add(key5);
 keyPanel.add(key6);
 keyPanel.add(key7);
 keyPanel.add(key8);
 keyPanel.add(key9);
 keyPanel.add(keyNo);
 keyPanel.add(key0);
 keyPanel.add(keyStar);

 // Assemble key/display panel
 keyDisplayPanel.add(display, BorderLayout.NORTH);
 keyDisplayPanel.add(keyPanel, BorderLayout.CENTER);
 
 // Assemble hook/state panel
 hookStatePanel.add(state, BorderLayout.NORTH);
 hookStatePanel.add(hook, BorderLayout.CENTER);

 // Add key/display panel and hook/state panel to frame
 add(hookStatePanel, BorderLayout.WEST);
 add(keyDisplayPanel, BorderLayout.CENTER);
 }
}