android写一个计时半小时

这里用Handler 做
//成员变量

private Handler mHandler;
private HandlerThread mWorkingThread = null;
private static final int THIRTY_MINUTES = 30;

                                    if (mWorkingThread == null) {
                                        mWorkingThread = new HandlerThread("monitor_time_data");
                                        mWorkingThread.start();
                                        mHandler = new BatteryCalibrationFragment.WorkHandler(mWorkingThread.getLooper());
                                        mHandler.sendEmptyMessageDelayed(THIRTY_MINUTES, 30 * 60 * 1000);
                                        PowerCalibrationNotificationHelp.sendNotificationInCalibration(getActivity());
                                        Log.e(TAG, "time...30begin");
                                    }

 private class WorkHandler extends Handler {
        public WorkHandler(Looper looper) {
            super(looper);
        }

        @Override
        public void handleMessage(Message msg) {
            switch (msg.what) {
                case THIRTY_MINUTES:
                    getActivity().runOnUiThread(new Runnable() {
                        @Override
                        public void run() {
                            if (getActivity() != null) {
                   //todo 写执行的方法就好了
                        }
                    });
                    break;
            }
        }
    }