LocationClient getLastLocation在我的片段中返回null

Question

我正在尝试使用LocationClient.getLastLocation（）获取当前位置。首先，我在onCreate（）中为LocationClient调用connect（），但它给了我这个错误：

11-11 13:20:45.297: E/AndroidRuntime(9188): Caused by: java.lang.IllegalStateException: Not connected. Call connect() and wait for onConnected() to be called.

然后我在onStart（）中为LocationClient调用connect（）。它给了我NullPointerException。

当我在onCreate（）中调用LocationClient的connect（）时，此代码在活动中运行良好。然而，它在碎片中不起作用。我应该在哪里为LocationClient调用connect（）？

ClosestFragment.java：

public class ClosestFragment extends Fragment implements
GooglePlayServicesClient.ConnectionCallbacks,
GooglePlayServicesClient.OnConnectionFailedListener {
    private GoogleMap map;
    JSONArray jsonArray;
    JSONObject jsonObject, jsonObjResult;
    String json = "";
    ProgressDialog progress;
    Location mCurrentLocation;
    LocationClient mLocationClient;
    SharedPreferences sp;
    Double latitude = 0.0;
    Double longitude = 0.0;
    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        // Get back arguments
    }
    @Override
    public View onCreateView(LayoutInflater inflater, ViewGroup container,
            Bundle savedInstanceState) {
        // Defines the xml file for the fragment
        View view = inflater.inflate(R.layout.closest_fragment, container, false);
        return view;
    }
    private boolean isNetworkAvailable() {
        ConnectivityManager connectivityManager = (ConnectivityManager) getActivity()
                .getSystemService(Context.CONNECTIVITY_SERVICE);
        NetworkInfo activeNetworkInfo = connectivityManager
                .getActiveNetworkInfo();
        return activeNetworkInfo != null && activeNetworkInfo.isConnected();
    }
    public static ClosestFragment newInstance() {
        ClosestFragment fragment = new ClosestFragment();
        return fragment;
    }
    @Override
    public void onStart() {
        super.onStart();
     // Connect the location client to start receiving updates
            mLocationClient = new LocationClient(getActivity(), this, this);
            mLocationClient.connect();  
    }
    @Override
    public void onActivityCreated(Bundle savedInstanceState) {
        super.onActivityCreated(savedInstanceState);

        FragmentManager fm = getChildFragmentManager();
        fm.beginTransaction()
                .replace(R.id.map, SupportMapFragment.newInstance()).commit();
        new GetClosestKiosks().execute();
    }
    private class GetClosestKiosks extends AsyncTask<Void, Void, Void> {

        String message="";
        ArrayList<KioskInfo> kioskList = new ArrayList<KioskInfo>();
        @Override
        protected void onPreExecute() {
            super.onPreExecute();
        }
        @Override
        protected Void doInBackground(Void... params) {
            Location mCurrentLocation = mLocationClient.getLastLocation();
            if (mCurrentLocation != null) {
                latitude = mCurrentLocation.getLatitude();
                Log.e("ASD", "" + latitude);
                longitude = mCurrentLocation.getLongitude();
                Log.e("ASD", "" + longitude);
            } else {
                sp = PreferenceManager
                        .getDefaultSharedPreferences(getActivity());
                String lat = sp.getString("lat", "0");
                String lon = sp.getString("lon", "0");
                latitude = Double.parseDouble(lat);
                longitude = Double.parseDouble(lon);
            }   
            return null;
        }
        @Override
        protected void onPostExecute(Void args) {
        }
    }
    @Override
    public void onConnectionFailed(ConnectionResult arg0) {
        // TODO Auto-generated method stub
    }
    @Override
    public void onConnected(Bundle arg0) {
        mCurrentLocation = mLocationClient.getLastLocation();
        if (mCurrentLocation != null) {
            latitude = mCurrentLocation.getLatitude();
            longitude = mCurrentLocation.getLongitude();
            String msg = "Updated Location: "
                    + Double.toString(mCurrentLocation.getLatitude()) + ","
                    + Double.toString(mCurrentLocation.getLongitude());
            // Toast.makeText(this, msg, Toast.LENGTH_SHORT).show();
            Log.d("DEBUG", "current location: " + mCurrentLocation.toString());
        } else {
            String lat = sp.getString("lat", "");
            String lon = sp.getString("lon", "");
            latitude = Double.parseDouble(lat);
            longitude = Double.parseDouble(lon);
        }
    }
    @Override
    public void onDisconnected() {
        // TODO Auto-generated method stub
    }
}

closest_fragment.xml

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:orientation="vertical"
    android:weightSum="20" >
    <FrameLayout
        android:id="@+id/map"
        class="com.google.android.gms.maps.SupportMapFragment"
        android:layout_width="fill_parent"
        android:layout_height="0dp"
        android:layout_weight="10" >
    </FrameLayout>
    <ListView
        android:id="@+id/kiosklist"
        android:layout_width="match_parent"
        android:layout_height="0dp"
        android:layout_weight="10" >
    </ListView>
</LinearLayout>

Answer 1

可能在LocationClient实际连接之前调用了GetClosestKiosks的doInBackground()方法。

因此，您应该在适当的地方致电您的new GetClosestKiosks().execute()。所以您可以在public void onConnected(Bundle arg0)方法内部调用它。

此外，您可能希望在doInBackground()方法中执行mLocationClient.requestLocationUpdates()，以获取最近的位置。