nameit.java

Java 入门书的源码

//Copyright (c) 1998, Arthur Gittleman
//This example is provided WITHOUT ANY WARRANTY either expressed or implied.

// Debugging Exercise 8.8 -- Has Errors

          import java.awt.*;
          import java.awt.event.*;
          import java.applet.Applet;
          public class NameIt extends Applet {
             Button draw = new Button("Draw");
             DrawOn canvas = new DrawOn();
             CheckboxGroup shapes = new CheckboxGroup();
             Checkbox square = new Checkbox("Square",false,shapes);
             Checkbox circle = new Checkbox("Circle",true,shapes);
             public void init() {
                 add(draw);
                 add(square);
                 add(circle);
                 add(canvas);
                 draw.addActionListener(canvas);
             }
             class DrawOn extends Canvas implements ActionListener {
                public void actionPerformed(ActionEvent event) {
                    repaint();
                }
                public void paint(Graphics g) {
                    if (circle.getState()){
                       g.fillOval(20,20,100,100);
                       g.drawString("Circle",40,40);
                    }
                    else {
                       g.fillRect(20,20,100,100);
                       g.drawString("Square",40,40);
                    }
                }   
             }
          }