buttonpress.java

Java 入门书的源码

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

/* A print button prints a message.
 * A clear button erases the message.
 * We use a Label component to hold
 * the message.
 */

import java.awt.*;
import java.awt.event.*;
import java.applet.Applet;

public class ButtonPress extends Applet 
                  implements ActionListener {
  private Button print = new Button("Print");
  private Button clear = new Button("Clear");
  private Label message = new Label("Message goes here");

  public void init() {
    add(message);
    add(print); 
    add(clear);
    print.addActionListener(this);
    clear.addActionListener(this);
  }
  public void actionPerformed(ActionEvent event) {
    Object source = event.getSource();
    if (source == print) 
      message.setText("Hi there");
    else if (source == clear) 
      message.setText("");
  }
}