안드로이드 프로그래밍 예제인데요..이상하게 글씨가 화면에 찍혀나오질 않습니다 좀 봐주세요~

public class Act1 extends Activity {
 
 @Override
 protected void onCreate(Bundle savedInstanceState) {
  super.onCreate(savedInstanceState);
  //setContentView(R.layout.act1);
 }
 
 protected class CanvasView extends View implements Runnable {
  private boolean mRun = false;
  private int mCount = 0;
 
  public CanvasView(Context context) {
   super(context);
  }
 
  public Handler mHandler = new Handler() {
   public void handleMessage(Message msg) {
    if (msg.what == 1) {
     invalidate();
    }
   }
  };
 
  @Override
  protected void onWindowVisibilityChanged(int visibility) {
   super.onWindowVisibilityChanged(visibility); //visibility == true
   if (visibility == View.VISIBLE && !mRun) {
    mRun = true;
    Thread thrd = new Thread(this);
    thrd.start();
   } else if (mRun) {
    mRun = false;
   }
  }
 
  @Override
  public void run() {
   while (mRun) {
    if (isShown())  //true
     mHandler.sendMessage(Message.obtain(mHandler, 1));
    try {
     Thread.sleep(100);
    } catch (InterruptedException e) {
     e.printStackTrace();
     break;
    }
   }
  }
 
  public void onDraw(Canvas canvas) {
   canvas.drawColor(Color.LTGRAY);
   Paint paint = new Paint(Paint.ANTI_ALIAS_FLAG);
   paint.setColor(Color.BLACK);
   canvas.drawText("Count: " + mCount++, 20, 20, paint);
  }
 }
 
 @Override
 public boolean onCreateOptionsMenu(Menu menu) {
  // Inflate the menu; this adds items to the action bar if it is present.
  getMenuInflater().inflate(R.menu.act1, menu);
  return true;
 }
 
}