traffic0.java

Java经典例程 从外国一大学计算机教授出版物下载的代码 经典

import java.awt.*;
import java.awt.event.*;

class Traffic0 extends Frame implements ActionListener {

    /* The first Traffic light program
     *                                 by J M Bishop Oct 1996
     *                      Java 1.1 by T Abbott October 1997
     *                            updated J M Bishop May 2000
     * Displays a representation of traffic lights,
     * in preparation for a simulation.
     *
     * NOTE: The walk button is not activated yet.
     * Illustrates panels and canvases and the
     * BorderLayout manager.
     */

    LightsCanvas lights;
    Button close;
    Button walk;

    Traffic0() {
      // Add the components
      Panel title = new Panel();
        title.add (new Label("Savanna Traffic Light Simulation"));
      add("North", title);
      lights = new LightsCanvas();
        add("Center", lights);
      Panel buttons = new Panel();
        walk = new Button("WALK");
          buttons.add(walk);
        close = new Button("CLOSE");
          close.addActionListener(this);
          buttons.add(close);
      add("South", buttons);

      // Set up the frame
      setTitle("Traffic Lights version 0");
      setSize(300,200);
      setVisible(true);
      addWindowListener(new WindowAdapter () {
        public void windowClosing(WindowEvent e) {
          System.exit(0);
        }
      });


    }

    public void actionPerformed(ActionEvent e) {
      // Must be the close button
      setVisible(false);
      dispose();
      System.exit(0);
    }

  public static void main(String[] args) {
      new Traffic0 ();
  }

  class LightsCanvas extends Canvas {
    public void paint(Graphics g) {
      g.drawOval(97, 10, 30, 68);
      g.setColor(Color.red);
      g.fillOval(105, 15, 15, 15);  // red
      g.setColor(Color.yellow);
      g.fillOval(105, 35, 15, 15);  // yellow
      g.setColor(Color.green);
      g.fillOval(105, 55, 15, 15);  // green
      g.fillOval(105, 85, 15, 15);  // walk
      g.setColor(Color.black);
      g.drawString("RED", 15, 28);
      g.drawString("YELLOW", 15, 48);
      g.drawString("GREEN", 15, 68);
      g.drawString("WALK", 15, 98);
    }
  }
}