cannonworldpanel.java

一些JAVA的小程序

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

public class CannonWorldPanel extends JPanel {
   public CannonWorldPanel() {
  }

  public static final int PanelWidth = 600;
  public static final int PanelHeight = 400;
  public Cannon cannon = new Cannon(new Point(20, PanelHeight -10));
  private CannonTarget target = new CannonTarget(new Point(PanelWidth - 100, PanelHeight - 15));
  private Ball aBall;
  private String message = "Angle: 45";

  public void paint (Graphics g) {
    super.paint(g);
    cannon.paint(g);
    target.paint(g);
    if(aBall != null) aBall.paint(g);
    g.drawString(message, PanelWidth/2, PanelHeight/2);
  }

  private void moveCannonBall() {
    aBall.move();
    //16 is radius of ball+diameter of target
    if (aBall.y() > PanelHeight-14){
      if (target.hitTarget(aBall.x()))
        message = "You Hit It!";
      else  message = "Missed!";
      aBall = null;
    }
  }

  public void run(){
    if(aBall != null) moveCannonBall();
    repaint();
    try{ Thread.sleep(50);} catch(Exception e) {System.exit(0);}
  }

  public void fire(){
    aBall = cannon.fire();
  }

  public void setAngle(int angle){
    cannon.setAngle(angle);
    message = "Angle: " + angle;
    repaint();
  }
}