twobuttons.java

HeadFirstCode系列图书里的源代码

import javax.swing.*;
import java.awt.*;
import java.awt.event.*;


public class TwoButtons  {

    JFrame frame;
    JLabel label;

    public static void main (String[] args) {
       TwoButtons gui = new TwoButtons();
       gui.go();
    }

    public void go() {
       frame = new JFrame();
       frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);

       JButton labelButton = new JButton("Change Label");
       labelButton.addActionListener(new LabelButtonListener());

       JButton colorButton = new JButton("Change Circle");
       colorButton.addActionListener(new ColorButtonListener());

       label = new JLabel("I'm a label");       
       MyDrawPanel drawPanel = new MyDrawPanel();
       
       frame.getContentPane().add(BorderLayout.SOUTH, colorButton);
       frame.getContentPane().add(BorderLayout.CENTER, drawPanel);
       frame.getContentPane().add(BorderLayout.EAST, labelButton);
       frame.getContentPane().add(BorderLayout.WEST, label);

       frame.setSize(420,300);
       frame.setVisible(true);
    }
    
     class LabelButtonListener implements ActionListener {
        public void actionPerformed(ActionEvent event) {
            label.setText("Ouch!");
        }
     } // close inner class

     class ColorButtonListener implements ActionListener {
        public void actionPerformed(ActionEvent event) {
            frame.repaint();
        }
     }  // close inner class
   
}

class MyDrawPanel extends JPanel {
    
      public void paintComponent(Graphics g) {
         
         g.fillRect(0,0,this.getWidth(), this.getHeight());

         // make random colors to fill with
         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(70,70,100,100);
      }

}