exercise12_3.java

java程序设计 机械工业出版社 书籍代码

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

public class Exercise12_3 extends JFrame {
  public Exercise12_3() {
    JButton jbtOK = new JButton("OK");
    JButton jbtCancel = new JButton("Cancel");
    MyDrawing canvas = new MyDrawing();
    canvas.setBackground(Color.WHITE);

    JPanel panel = new JPanel();
    panel.add(jbtOK);
    panel.add(jbtCancel);

    getContentPane().add(panel, BorderLayout.SOUTH);
    getContentPane().add(canvas, BorderLayout.CENTER);

    jbtOK.addActionListener(canvas);
    jbtCancel.addActionListener(canvas);
  }

  public static void main(String[] args) {
    JFrame frame = new Exercise12_3();
    frame.setTitle("Exercise12_3");
    frame.setSize(300, 300);
    frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
    frame.setVisible(true);
  }
}

class MyDrawing extends JPanel implements ActionListener {
  private String message = "";

  public void actionPerformed(ActionEvent e) {
    message = e.getActionCommand() + " is clicked";
    repaint();
  }

  public void paintComponent(Graphics g) {
    super.paintComponent(g);

    g.drawString(message, 20, 20);
  }
}