1 import javax.swing.*; 2 import java.awt.event.*; 3 import java.awt.*; 4  5 class MyPanel_2 extends JPanel { 6     public void paintComponent( Graphics g ) { 7         g.fillRect(0, 0, this.getWidth(), this.getHeight()); 8         int red = (int) (Math.random() * 255); 9         int green = (int) (Math.random() * 255);10         int blue = (int) (Math.random() * 255);11         Color randomColor = new Color(red, green, blue);12         g.setColor(randomColor);13         g.fillOval(70, 40, 100, 100);14     }15 }16 17 class Gui{18     19     JButton button = new JButton("change color");20     JButton button_change_label = new JButton("change label");21     JLabel label = new JLabel("I‘m a label");22     JFrame frame = new JFrame();23     24     private void set_frame() {25         frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);26         frame.setSize(800, 600);27         frame.setVisible(true);28     }29     30     public void show_my_panel() {31         set_frame();32         frame.getContentPane().add(BorderLayout.SOUTH, button);33         button.addActionListener(new ColorButtonActionListener());34 35         frame.getContentPane().add(BorderLayout.EAST, button_change_label);36         button_change_label.addActionListener(new LabelButtonActionListener() );37         38         frame.getContentPane().add(BorderLayout.WEST, label);39         40         frame.getContentPane().add(BorderLayout.CENTER,new MyPanel_2());41     }42 43     class ColorButtonActionListener implements ActionListener {44         public void actionPerformed( ActionEvent event ) {45             frame.repaint();46         }47     }48 49     class LabelButtonActionListener implements ActionListener {50         public void actionPerformed( ActionEvent event ) {51             label.setText("That hurt!");52         }53     }54 }55 56 class GuiTest {57     public static void main( String[] args ) {58         Gui gui = new Gui();59         gui.show_my_panel();60     }61 }