animationdemo.java

JAVA程序设计导论那本书上的一些源代码. 在学那本书的下来的

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

public class AnimationDemo extends JFrame {
  public AnimationDemo() {
    // Create a MovingMessagePanel for displaying a moving message
    MovingMessagePanel p = new MovingMessagePanel("message moving?");
    getContentPane().add(p);

    // Create a timer for the listener p
    Timer timer = new Timer(1000, p);
    timer.start();
  }

  /** Main method */
  public static void main(String[] args) {
    AnimationDemo frame = new AnimationDemo();
    frame.setTitle("AnimationDemo");
    frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
    frame.setSize(100, 280);
    frame.setVisible(true);
  }
}

// Displaying a moving message
class MovingMessagePanel extends JPanel implements ActionListener {
  private String message = "Welcome to Java";
  private int xCoordinate = 20;
  private int yCoordinate = 20;

  public MovingMessagePanel(String message) {
    this.message = message;
  }

  /** Handle ActionEvent */
  public void actionPerformed(ActionEvent e) {
    repaint();
  }

  /** Paint message */
  public void paintComponent(Graphics g) {
    super.paintComponent(g);

    if (xCoordinate > getWidth()) xCoordinate = -20;
    xCoordinate += 5;
    g.drawString(message, xCoordinate, yCoordinate);
  }
}