android 控件Button循环焦点

这个是四个按键为例子.

    int mFocus = 0;
	public boolean onKeyDown(int keyCode, KeyEvent event) {
		if (keyCode == KeyEvent.KEYCODE_DPAD_LEFT) {
			mFocus--;
			if (mFocus < 0) {
				mFocus = 3;
				Button4.requestFocus();
				return true;
			}
		}
		if (keyCode == KeyEvent.KEYCODE_DPAD_RIGHT) {
			mFocus++;
			if (mFocus >= 4) {
				mFocus = 0;
				Button1.requestFocus();
				return true;
			}
		}
		return super.onKeyDown(keyCode, event);
	}