Android：如何使用postDelayed方法从Runnable获取数据？

Question

我使用Runnable从GPS设备获取数据，但有时无法从外部获取数据，尽管内部的值总是有价值。

BaseSevice.java

protected Handler mHandler = new Handler();
protected volatile String mRawLine;
protected Runnable mReadDeviceDataTask = new Runnable() {
    public void run() {
        int delay = Constants.DEFAULT_GET_DATA_INTERVAL;        //interval = 100ms
        if (deviceType() == DeviceSupport.GPS) {
            delay = Constants.GPS_GET_DATA_INTERVAL;            //interval = 10ms
        }

        if (mDevice == null) {
            mHandler.postDelayed(mReadDeviceDataTask, delay);
            return;
        }
        try {
            if (mInputStream.available() > 0) {
                mRawLine = "some data here get from GPS device";        //data got continuously & many lines
            }
        } catch (IOException ioEx) {
            throw new RuntimeException("Can not read lines from socket", ioEx);
        } catch (Exception e) {
            throw new RuntimeException("Error while read from input stream", e);
        }
        mHandler.postDelayed(mReadDeviceDataTask, delay);
    }
};

GPSService.java 扩展了BaseService

public String getmRawLine() { Log.e("debug","return mRawLine:" + mRawLine); return mRawLine;//<--- sometimes there is no value }