GPS定位服務中的Nullpointerexception

我得到了一個nullpointerexception。我檢查庫和所有，但無法修復它。也許可能是上下文？ ontext。或者是我在代碼中缺少的東西。GPS定位服務中的Nullpointerexception

任何幫助將是apreciated。調試只是說.... nullpointerex ... 這是我的java類：

package bla; 




import java.io.BufferedReader; 
import java.io.IOException; 
import java.io.InputStream; 
import java.io.InputStreamReader; 
import java.net.HttpURLConnection; 
import java.net.URL; 
import java.util.HashMap; 
import java.util.List; 

import org.json.JSONObject; 

import android.support.v4.app.FragmentActivity; 
import android.support.v4.app.FragmentManager; 
import android.support.v4.app.Fragment; 

import com.google.android.gms.maps.CameraUpdateFactory; 
import com.google.android.gms.maps.SupportMapFragment; 
import com.google.android.gms.maps.MapFragment; 

import android.support.v4.app.FragmentManager; 

import com.google.android.gms.maps.GoogleMap; 
import com.google.android.gms.maps.model.LatLng; 
import com.google.android.gms.maps.model.MarkerOptions; 

import android.app.Activity; 
import android.app.FragmentTransaction; 
import android.os.Bundle; 
import android.view.View; 
import android.widget.Button; 
import android.widget.Toast; 
import android.app.Activity; 
import android.content.Context; 
import android.location.Criteria; 
import android.location.Location; 
import android.location.LocationListener; 
import android.location.LocationManager; 
import android.os.Bundle; 
import android.view.View; 
import android.widget.Button; 
import android.widget.Toast; 
import android.os.Bundle; 
import android.view.InflateException; 
import android.view.LayoutInflater; 
import android.view.Menu; 
import android.view.View; 
import android.view.ViewGroup; 
import android.widget.TextView; 
import android.os.Bundle; 
import android.support.v4.app.Fragment; 
import android.view.LayoutInflater; 
import android.view.View; 
import android.view.ViewGroup; 
import android.widget.TextView; 
import android.app.AlertDialog; 
import android.app.Service; 
import android.content.Context; 
import android.content.DialogInterface; 
import android.content.Intent; 

import android.os.AsyncTask; 
import android.os.Bundle; 
import android.os.IBinder; 
import android.provider.Settings; 
import android.util.Log; 
import android.content.Context; 
import android.os.Bundle; 
import android.view.LayoutInflater; 
import android.view.View; 
import android.view.ViewGroup; 
import android.widget.TextView; 
import java.io.BufferedReader; 
import java.io.IOException; 
import java.io.InputStream; 
import java.io.InputStreamReader; 
import java.net.HttpURLConnection; 
import java.net.URL; 
import java.util.HashMap; 
import java.util.List; 

import org.json.JSONObject; 

import android.app.Dialog; 
import android.os.AsyncTask; 
import android.os.Bundle; 
import android.support.v4.app.FragmentActivity; 
import android.util.Log; 
import android.view.Menu; 
import android.view.View; 
import android.view.View.OnClickListener; 
import android.widget.ArrayAdapter; 
import android.widget.Button; 
import android.widget.Spinner; 

import com.google.android.gms.common.ConnectionResult; 
import com.google.android.gms.common.GooglePlayServicesUtil; 
import com.google.android.gms.maps.CameraUpdateFactory; 
import com.google.android.gms.maps.GoogleMap; 
import com.google.android.gms.maps.SupportMapFragment; 
import com.google.android.gms.maps.model.LatLng; 
import com.google.android.gms.maps.model.MarkerOptions; 

public class RiverFragment extends Fragment implements LocationListener { 


protected LocationManager locationManager; 
// GoogleMap googleMap; 

LatLng myPosition; 
private SupportMapFragment map; 
private GoogleMap mMapView; 
int fragVal2; 
static Context ontext; 
private static View view; 


//lo que se ocupa para construir los sitios 

String[] mPlaceType=null; 
String[] mPlaceTypeName=null; 

double mLatitude=0; 
double mLongitude=0; 


    @Override 
    public View onCreateView(LayoutInflater inflater, ViewGroup container, 
      Bundle savedInstanceState) { 

     // Array of place types 
       mPlaceType = getResources().getStringArray(R.array.rivers); 

       // Array of place type names 
       mPlaceTypeName = getResources().getStringArray(R.array.rivers2); 

     if (view != null) { 
      ViewGroup parent = (ViewGroup) view.getParent(); 
      if (parent != null) 
       parent.removeView(view); 
     } 
     try { 
      view = inflater.inflate(R.layout.fragment_layout, container, 
        false); 

      android.support.v4.app.FragmentManager fm = getFragmentManager(); 
      map = (SupportMapFragment) fm.findFragmentById(R.id.map); 
      if (map == null) { 
       map = SupportMapFragment.newInstance(); 
       fm.beginTransaction().replace(R.id.map, map).commit(); 
      } 

      // mMapView = fm.getMap(); 
      mMapView = map.getMap(); 
       // Enabling MyLocation Layer of Google Map 
      mMapView.setMyLocationEnabled(true); 

      // Getting LocationManager object from System Service LOCATION_SERVICE 
      LocationManager locationManager = (LocationManager) ontext.getSystemService(Context.LOCATION_SERVICE); 

      // Creating a criteria object to retrieve provider 
      Criteria criteria = new Criteria(); 

      // Getting the name of the best provider 
      String provider = locationManager.getBestProvider(criteria, true); 

      // Getting Current Location From GPS 
      Location location = locationManager.getLastKnownLocation(provider); 

      if(location!=null){ 
       onLocationChanged(location); 
     } 

     locationManager.requestLocationUpdates(provider, 20000, 0, this); 

     // Getting reference to the TextView of the Fragment 
     //TextView tv = (TextView) view.findViewById(R.id.tv_content); 

     // Retrieving the currently selected item number 
      int position = getArguments().getInt("position"); 

      // List of rivers 
      String[] rivers = getResources().getStringArray(R.array.rivers); 

     // Setting currently selected river name in the TextView 
      String type = mPlaceType[position];  

      StringBuilder sb = new StringBuilder("https://maps.googleapis.com/maps/api/place/nearbysearch/json?"); 
      sb.append("location="+mLatitude+","+mLongitude); 
      sb.append("&radius=5000"); 
      sb.append("&types="+type); 
      sb.append("&sensor=true"); 
      sb.append("&key=yeah"); 


      // Creating a new non-ui thread task to download Google place json data 
      PlacesTask placesTask = new PlacesTask();         

      // Invokes the "doInBackground()" method of the class PlaceTask 
      placesTask.execute(sb.toString()); 



     // Updating the action bar title 
//  getActivity().getActionBar().setTitle(rivers[position]); 

     //return layoutView; 


     // Retrieving the currently selected item number 
      // int position = getArguments().getInt("position"); 

       // List of rivers 
      // String[] rivers = getResources().getStringArray(R.array.rivers); 

       // Creating view correspoding to the fragment 

     } catch (InflateException e) { 
      /* map is already there, just return view as it is */ 
     } 
     return view; 
     } 



    /** A method to download json data from url */ 
    private String downloadUrl(String strUrl) throws IOException{ 
     String data = ""; 
     InputStream iStream = null; 
     HttpURLConnection urlConnection = null; 
     try{ 
       URL url = new URL(strUrl);     


       // Creating an http connection to communicate with url 
       urlConnection = (HttpURLConnection) url.openConnection();     

       // Connecting to url 
       urlConnection.connect();     

       // Reading data from url 
       iStream = urlConnection.getInputStream(); 

       BufferedReader br = new BufferedReader(new InputStreamReader(iStream)); 

       StringBuffer sb = new StringBuffer(); 

       String line = ""; 
       while((line = br.readLine()) != null){ 
         sb.append(line); 
       } 

       data = sb.toString(); 

       br.close(); 

     }catch(Exception e){ 
       Log.d("Exception while downloading url", e.toString()); 
     }finally{ 
       iStream.close(); 
       urlConnection.disconnect(); 
     } 

     return data; 
    }   


    /** A class, to download Google Places */ 
    private class PlacesTask extends AsyncTask<String, Integer, String>{ 

     String data = null; 

     // Invoked by execute() method of this object 
     @Override 
     protected String doInBackground(String... url) { 
      try{ 
       data = downloadUrl(url[0]); 
      }catch(Exception e){ 
       Log.d("Background Task",e.toString()); 
      } 
      return data; 
     } 

     // Executed after the complete execution of doInBackground() method 
     @Override 
     protected void onPostExecute(String result){    
      ParserTask parserTask = new ParserTask(); 

      // Start parsing the Google places in JSON format 
      // Invokes the "doInBackground()" method of the class ParseTask 
      parserTask.execute(result); 
     } 

    } 

    /** A class to parse the Google Places in JSON format */ 
    private class ParserTask extends AsyncTask<String, Integer, List<HashMap<String,String>>>{ 

     JSONObject jObject; 

     // Invoked by execute() method of this object 
     @Override 
     protected List<HashMap<String,String>> doInBackground(String... jsonData) { 

      List<HashMap<String, String>> places = null;    
      PlaceJSONParser placeJsonParser = new PlaceJSONParser(); 

      try{ 
       jObject = new JSONObject(jsonData[0]); 

       /** Getting the parsed data as a List construct */ 
       places = placeJsonParser.parse(jObject); 

      }catch(Exception e){ 
        Log.d("Exception",e.toString()); 
      } 
      return places; 
     } 

     // Executed after the complete execution of doInBackground() method 
     @Override 
     protected void onPostExecute(List<HashMap<String,String>> list){    

      // Clears all the existing markers 
      mMapView.clear(); 

      for(int i=0;i<list.size();i++){ 

       // Creating a marker 
       MarkerOptions markerOptions = new MarkerOptions(); 

       // Getting a place from the places list 
       HashMap<String, String> hmPlace = list.get(i); 

       // Getting latitude of the place 
       double lat = Double.parseDouble(hmPlace.get("lat"));     

       // Getting longitude of the place 
       double lng = Double.parseDouble(hmPlace.get("lng")); 

       // Getting name 
       String name = hmPlace.get("place_name"); 

       // Getting vicinity 
       String vicinity = hmPlace.get("vicinity"); 

       LatLng latLng = new LatLng(lat, lng); 

       // Setting the position for the marker 
       markerOptions.position(latLng); 

       // Setting the title for the marker. 
       //This will be displayed on taping the marker 
       markerOptions.title(name + " : " + vicinity);    

       // Placing a marker on the touched position 
       mMapView.addMarker(markerOptions);    

      }  

     } 

    } 



/* @Override 
    public boolean onCreateOptionsMenu(Menu menu) { 
     // Inflate the menu; this adds items to the action bar if it is present. 
     getMenuInflater().inflate(R.menu.activity_main, menu); 
     return true; 
    } */ 

    @Override 
    public void onLocationChanged(Location location) { 
     mLatitude = location.getLatitude(); 
     mLongitude = location.getLongitude(); 
     LatLng latLng = new LatLng(mLatitude, mLongitude); 

     mMapView.moveCamera(CameraUpdateFactory.newLatLng(latLng)); 
     mMapView.animateCamera(CameraUpdateFactory.zoomTo(12)); 

    } 

    @Override 
    public void onStatusChanged(String provider, int status, Bundle extras) { 
     // TODO Auto-generated method stub 

    } 

    @Override 
    public void onProviderEnabled(String provider) { 
     // TODO Auto-generated method stub 

    } 

    @Override 
    public void onProviderDisabled(String provider) { 
     // TODO Auto-generated method stub 

    } 
    /* 
    @Override 
    public void onDestroyView() { 
     super.onDestroyView(); 
     MapFragment f = (MapFragment) getFragmentManager().findFragmentById(R.id.map); 
if (f != null) 
getFragmentManager().beginTransaction().remove(f).commit(); 
    } */ 
}

的錯誤是在這一部分：

// Getting LocationManager object from System Service LOCATION_SERVICE 
      LocationManager locationManager = (LocationManager) ontext.getSystemService(Context.LOCATION_SERVICE);

日誌說

06-10 19:58:53.423: E/AndroidRuntime(30871): FATAL EXCEPTION: main 
06-10 19:58:53.423: E/AndroidRuntime(30871): java.lang.NullPointerException 
06-10 19:58:53.423: E/AndroidRuntime(30871): at in.wptrafficanalyzer.navigationdrawerdemo.RiverFragment.onCreateView(RiverFragment.java:163) 
06-10 19:58:53.423: E/AndroidRuntime(30871): at android.support.v4.app.Fragment.performCreateView(Fragment.java:1460) 
06-10 19:58:53.423: E/AndroidRuntime(30871): at android.support.v4.app.FragmentManagerImpl.moveToState(FragmentManager.java:911) 
06-10 19:58:53.423: E/AndroidRuntime(30871): at android.support.v4.app.FragmentManagerImpl.moveToState(FragmentManager.java:1088) 
06-10 19:58:53.423: E/AndroidRuntime(30871): at android.support.v4.app.BackStackRecord.run(BackStackRecord.java:682) 
06-10 19:58:53.423: E/AndroidRuntime(30871): at android.support.v4.app.FragmentManagerImpl.execPendingActions(FragmentManager.java:1444) 
06-10 19:58:53.423: E/AndroidRuntime(30871): at android.support.v4.app.FragmentManagerImpl$1.run(FragmentManager.java:429) 
06-10 19:58:53.423: E/AndroidRuntime(30871): at android.os.Handler.handleCallback(Handler.java:615) 
06-10 19:58:53.423: E/AndroidRuntime(30871): at android.os.Handler.dispatchMessage(Handler.java:92) 
06-10 19:58:53.423: E/AndroidRuntime(30871): at android.os.Looper.loop(Looper.java:153) 
06-10 19:58:53.423: E/AndroidRuntime(30871): at android.app.ActivityThread.main(ActivityThread.java:4987) 
06-10 19:58:53.423: E/AndroidRuntime(30871): at java.lang.reflect.Method.invokeNative(Native Method) 
06-10 19:58:53.423: E/AndroidRuntime(30871): at java.lang.reflect.Method.invoke(Method.java:511) 
06-10 19:58:53.423: E/AndroidRuntime(30871): at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:821) 
06-10 19:58:53.423: E/AndroidRuntime(30871): at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:584) 
06-10 19:58:53.423: E/AndroidRuntime(30871): at dalvik.system.NativeStart.main(Native Method)

來源

2014-06-11 arnoldssss

未來，當說'NullPointerException'（或任何其他'Exception'）時，請發佈Logcat。 – Onik

您沒有初始化'Context ontext'，所以它是'null'。之前提到的線''ontext = ...;' – Onik

好吧，讓我來添加它 – arnoldssss

引用它時，變量ontext（上下文）爲空。
我不知道你在哪裏初始化它。
在使用之前進行初始化。或者你可以使用

LocationManager locationManager = (LocationManager) getActivity().getSystemService(Context.LOCATION_SERVICE);

來源

2014-06-11 00:58:32

好吧讓我測試，謝謝 – arnoldssss

這工作我現在面臨爲什麼它不顯示銀行的標記：/ – arnoldssss

GPS定位服務中的Nullpointerexception

回答

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