无法将库类强制转换为片段

我在m项目中添加了雅虎天气库。然后我尝试将YahooWeatherInfoListener实现到主片段中。

有个问题。

在AsyncTask内部，我无法将YahooWeatherInfoListener投射到片段中。

我觉得AsncTask里面有我做错的事。请看一下：

import zh.wang.android.apis.yweathergetter4a.WeatherInfo;
import zh.wang.android.apis.yweathergetter4a.YahooWeather;
import zh.wang.android.apis.yweathergetter4a.YahooWeather.SEARCH_MODE;
import zh.wang.android.apis.yweathergetter4a.YahooWeatherInfoListener;
import android.app.Fragment;
import android.os.AsyncTask;
import android.os.Bundle;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.TextView;
public class HomeFragment extends Fragment implements YahooWeatherInfoListener {
public HomeFragment(){}
private TextView Temperature;
private YahooWeather mYahooWeather = YahooWeather.getInstance(5000, 5000, true);
@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
        Bundle savedInstanceState) {
    View rootView = inflater.inflate(R.layout.fragment_home, container, false);
    Temperature = (TextView) rootView.findViewById(R.id.txtLabel);
    new searchByGPS().execute();
    return rootView;
}
private class searchByGPS extends AsyncTask<Void, Void, Void>{
    @Override
    protected void onPreExecute() {
    }
    @Override
    protected Void doInBackground(Void... unused) {
        mYahooWeather.setNeedDownloadIcons(true);
        mYahooWeather.setSearchMode(SEARCH_MODE.GPS);
        mYahooWeather.queryYahooWeatherByGPS(getActivity().getApplicationContext(), (YahooWeatherInfoListener) this);
        return null;
    }
    protected void onPostExecute(Void unused) {
    }
}
@Override
public void gotWeatherInfo(WeatherInfo weatherInfo) {
    // TODO Auto-generated method stub
    Temperature.setText(weatherInfo.getCurrentTempC());
}
}

(YahooWeatherInfoListener) this

(YahooWeatherInfoListener) HomeFragment.this

private class SearchByGPSTask extends AsyncTask<Void, Void, Void>{
    private YahooWeatherInfoListener mListener;
    public SearchByGPSTask( YahooWeatherInfoListener listener ) {
        super();
        mListener = listener;
    }
    @Override
    protected void onPreExecute() {
    }
    @Override
    protected Void doInBackground(Void... unused) {
        mYahooWeather.setNeedDownloadIcons(true);
        mYahooWeather.setSearchMode(SEARCH_MODE.GPS);
        mYahooWeather.queryYahooWeatherByGPS(getActivity().getApplicationContext(), mListener );
        return null;
    }
    protected void onPostExecute(Void unused) {
    }
}

protected Void doInBackground(Void... unused) {
        mYahooWeather.setNeedDownloadIcons(true);
        mYahooWeather.setSearchMode(SEARCH_MODE.GPS);
        mYahooWeather.queryYahooWeatherByGPS(getActivity().getApplicationContext(), (YahooWeatherInfoListener) HomeFragment.this);
        return null;
    }