import javax.swing.*;

 import java.awt.event.*;

 import java.awt.*;

 class MyPanel_2 extends JPanel {

     public void paintComponent( Graphics g ) {

         g.fillRect(0, 0, this.getWidth(), this.getHeight());

         int red = (int) (Math.random() * 255);

         int green = (int) (Math.random() * 255);

         int blue = (int) (Math.random() * 255);

         Color randomColor = new Color(red, green, blue);

         g.setColor(randomColor);

         g.fillOval(70, 40, 100, 100);

     }

 }

 class Gui{

     JButton button = new JButton("change color");

     JButton button_change_label = new JButton("change label");

     JLabel label = new JLabel("I'm a label");

     JFrame frame = new JFrame();

     private void set_frame() {

         frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);

         frame.setSize(800, 600);

         frame.setVisible(true);

     }

     public void show_my_panel() {

         set_frame();

         frame.getContentPane().add(BorderLayout.SOUTH, button);

         button.addActionListener(new ColorButtonActionListener());

         frame.getContentPane().add(BorderLayout.EAST, button_change_label);

         button_change_label.addActionListener(new LabelButtonActionListener() );

         frame.getContentPane().add(BorderLayout.WEST, label);

         frame.getContentPane().add(BorderLayout.CENTER,new MyPanel_2());

     }

     class ColorButtonActionListener implements ActionListener {

         public void actionPerformed( ActionEvent event ) {

             frame.repaint();

         }

     }

     class LabelButtonActionListener implements ActionListener {

         public void actionPerformed( ActionEvent event ) {

             label.setText("That hurt!");

         }

     }

 }

 class GuiTest {

     public static void main( String[] args ) {

         Gui gui = new Gui();

         gui.show_my_panel();

     }

 }