public class helloWorld extends Activity {
 
    /** Called when the activity is first created. */
    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState)
 
;
 
        setContentView( new View(null){
 
            Paint vPaint = new Paint();  //繪製樣式物件
            private int i = 0;           //弧形角度
 
            @Override
            protected void onDraw (Canvas canvas) {
                // TODO Auto-generated method stub
                super.onDraw(canvas)
 
;
 
                // 設定繪圖樣式
                vPaint.setColor( 0xff00ffff ); //畫筆顏色
                vPaint.setAntiAlias( true );   //反鋸齒
                vPaint.setStyle( Paint.Style.STROKE );
 
                // 繪製一個弧形
                canvas.drawArc(new RectF(60, 120, 260, 320), 0, i, true, vPaint );
 
                // 弧形角度
 

                if( (i+=10) > 360 )
                    i = 0;
 
                // 重繪, 再一次執行onDraw 程式
                invalidate();
            }
        });
    }
}