changecolors.java

《精通JAVA手机游戏与应用程序设计》随书光盘

import javax.microedition.lcdui.*;
import javax.microedition.midlet.*;


public class ChangeColors extends MIDlet implements CommandListener {

	private Command exitCommand;
	private ChangeColorsCanvas sg;

	public ChangeColors() {
		exitCommand = new Command("Exit", Command.EXIT, 1);
		sg = new ChangeColorsCanvas();
		sg.addCommand(exitCommand);
		sg.setCommandListener(this);
		Display.getDisplay(this).setCurrent(sg);
		
	}
	protected void startApp(){
	}

	protected void pauseApp() {
	}

	protected void destroyApp(boolean arg0){		
	}
	public void commandAction(Command c, Displayable d) {
		if (c == exitCommand) {			
			destroyApp(false);			
			notifyDestroyed();
		}
	}	
}

class ChangeColorsCanvas extends Canvas{
	
	protected void paint(Graphics g) {		
		int i = 0;
		int width = 255;
		//画出灰色阶层
		for(i=0;i<=width;i++){
			g.setGrayScale(i);
			g.drawLine(i,10,i,60);
		}
		//转移原点
		g.translate(20,70);
		//画饼图
		g.setColor(255, 0, 0);
        g.fillArc(0, 0, 100, 100, 45, 270);
        g.setColor(0, 255, 0);
        g.fillArc(0, 0, 100, 100, 0, 45);
        g.setColor(0, 0, 255);
        g.fillArc(0, 0, 100, 100, 0, -45);
        g.setColor(0);
        g.drawArc(0, 0, 100, 100, 0, 360);
		
		
	}
	
}