donghua.txt

j2me ballCavans CommandListener

package cn;

import javax.microedition.lcdui.Canvas;
import javax.microedition.lcdui.Command;
import javax.microedition.lcdui.CommandListener;
import javax.microedition.lcdui.Display;
import javax.microedition.lcdui.Displayable;
import javax.microedition.lcdui.Graphics;
import javax.microedition.midlet.MIDlet;
import javax.microedition.midlet.MIDletStateChangeException;

public class MIDlet1 extends MIDlet{

	private BallCanvas bc=new BallCanvas();
	private Display dis;
	
	protected void startApp() throws MIDletStateChangeException{
		dis=Display.getDisplay(this);
		dis.setCurrent(bc);
	}

	protected void destroyApp(boolean arg0) throws MIDletStateChangeException{}
	protected void pauseApp(){}
	
	class BallCanvas extends Canvas  implements Runnable,CommandListener{
		private int left=50;
		private int top=50;
		private int d=100;
		private int DIR=1;//1向下 2向上
	
		private Command cmdPause=new Command("暂停",Command.SCREEN,1);
		private Command cmdResume=new Command("继续",Command.SCREEN,1);
		private Thread th;
		private boolean RUN=true;

		public BallCanvas(){
			this.addCommand(cmdPause);
			this.setCommandListener(this);
			th=new Thread(this);
			th.start();			
		}		
		public void commandAction(Command c,Displayable d){
			if(c==cmdPause){//按下暂停按钮
				this.removeCommand(cmdPause);
				this.addCommand(cmdResume);
				RUN=false;
				th=null;
			}else if(c==cmdResume){//继续按钮
				this.removeCommand(cmdResume);
				this.addCommand(cmdPause);	
				RUN=true;
				th=new Thread(this);
				th.start();
			}
		}


		public void paint(Graphics g){
			g.setColor(0,255,0);//绿色
			g.fillRect(0,0,this.getWidth(),this.getHeight());
			g.setColor(255,0,0);
			g.fillArc(left,top,d,d,0,360);
		}
		public void run(){
			while(RUN){
				if(DIR==1){
					top+=3;
					d--;
					if(top>=this.getHeight()-d){
						DIR=2;
					}
				}
				if(DIR==2){
					top-=3;
					d++;
					if(top<=50){
						DIR=1;
					}
					
				}
				repaint();//重画
				try{
					Thread.currentThread().sleep(10);
				}catch(Exception e){
					e.printStackTrace();
				}
	
			}
		}
	
		


}


	

}