NullPointerException - 使用片段中的位置

Question

尝试运行应用程序时，我意外地收到以下NullPointer异常错误。

09-22 20:22:49.981: E/AndroidRuntime(4751): FATAL EXCEPTION: main 
    09-22 20:22:49.981: E/AndroidRuntime(4751): Process: com.dooba.beta, PID: 4751 
    09-22 20:22:49.981: E/AndroidRuntime(4751): java.lang.NullPointerException 
    09-22 20:22:49.981: E/AndroidRuntime(4751):  at com.dooba.beta.Fragment1.setConversationsList(Fragment1.java:154) 
    09-22 20:22:49.981: E/AndroidRuntime(4751):  at com.dooba.beta.Fragment1.onActivityCreated(Fragment1.java:97) 
    09-22 20:22:49.981: E/AndroidRuntime(4751):  at android.support.v4.app.Fragment.performActivityCreated(Fragment.java:1468) 
    09-22 20:22:49.981: E/AndroidRuntime(4751):  at android.support.v4.app.FragmentManagerImpl.moveToState(FragmentManager.java:931) 
    09-22 20:22:49.981: E/AndroidRuntime(4751):  at android.support.v4.app.FragmentManagerImpl.moveToState(FragmentManager.java:1088) 
    09-22 20:22:49.981: E/AndroidRuntime(4751):  at android.support.v4.app.BackStackRecord.run(BackStackRecord.java:682) 
    09-22 20:22:49.981: E/AndroidRuntime(4751):  at android.support.v4.app.FragmentManagerImpl.execPendingActions(FragmentManager.java:1444) 
    09-22 20:22:49.981: E/AndroidRuntime(4751):  at android.support.v4.app.FragmentManagerImpl.executePendingTransactions(FragmentManager.java:461) 
    09-22 20:22:49.981: E/AndroidRuntime(4751):  at android.support.v4.app.FragmentPagerAdapter.finishUpdate(FragmentPagerAdapter.java:141) 
    09-22 20:22:49.981: E/AndroidRuntime(4751):  at android.support.v4.view.ViewPager.populate(ViewPager.java:1011) 
    09-22 20:22:49.981: E/AndroidRuntime(4751):  at android.support.v4.view.ViewPager.populate(ViewPager.java:880) 
    09-22 20:22:49.981: E/AndroidRuntime(4751):  at android.support.v4.view.ViewPager.onMeasure(ViewPager.java:1374) 
    09-22 20:22:49.981: E/AndroidRuntime(4751):  at android.view.View.measure(View.java:16497) 
    09-22 20:22:49.981: E/AndroidRuntime(4751):  at android.view.ViewGroup.measureChildWithMargins(ViewGroup.java:5125) 
    09-22 20:22:49.981: E/AndroidRuntime(4751):  at android.widget.LinearLayout.measureChildBeforeLayout(LinearLayout.java:1404) 
    09-22 20:22:49.981: E/AndroidRuntime(4751):  at android.widget.LinearLayout.measureVertical(LinearLayout.java:695) 
    09-22 20:22:49.981: E/AndroidRuntime(4751):  at android.widget.LinearLayout.onMeasure(LinearLayout.java:588) 
    09-22 20:22:49.981: E/AndroidRuntime(4751):  at android.view.View.measure(View.java:16497) 
    09-22 20:22:49.981: E/AndroidRuntime(4751):  at android.view.ViewGroup.measureChildWithMargins(ViewGroup.java:5125) 
    09-22 20:22:49.981: E/AndroidRuntime(4751):  at android.widget.FrameLayout.onMeasure(FrameLayout.java:310) 
    09-22 20:22:49.981: E/AndroidRuntime(4751):  at android.view.View.measure(View.java:16497) 
    09-22 20:22:49.981: E/AndroidRuntime(4751):  at android.view.ViewGroup.measureChildWithMargins(ViewGroup.java:5125) 
    09-22 20:22:49.981: E/AndroidRuntime(4751):  at com.android.internal.widget.ActionBarOverlayLayout.onMeasure(ActionBarOverlayLayout.java:327) 
    09-22 20:22:49.981: E/AndroidRuntime(4751):  at android.view.View.measure(View.java:16497) 
    09-22 20:22:49.981: E/AndroidRuntime(4751):  at android.view.ViewGroup.measureChildWithMargins(ViewGroup.java:5125) 
    09-22 20:22:49.981: E/AndroidRuntime(4751):  at android.widget.FrameLayout.onMeasure(FrameLayout.java:310) 
    09-22 20:22:49.981: E/AndroidRuntime(4751):  at com.android.internal.policy.impl.PhoneWindow$DecorView.onMeasure(PhoneWindow.java:2291) 
    09-22 20:22:49.981: E/AndroidRuntime(4751):  at android.view.View.measure(View.java:16497) 
    09-22 20:22:49.981: E/AndroidRuntime(4751):  at android.view.ViewRootImpl.performMeasure(ViewRootImpl.java:1916) 
    09-22 20:22:49.981: E/AndroidRuntime(4751):  at android.view.ViewRootImpl.measureHierarchy(ViewRootImpl.java:1113) 
    09-22 20:22:49.981: E/AndroidRuntime(4751):  at android.view.ViewRootImpl.performTraversals(ViewRootImpl.java:1295) 
    09-22 20:22:49.981: E/AndroidRuntime(4751):  at android.view.ViewRootImpl.doTraversal(ViewRootImpl.java:1000) 
    09-22 20:22:49.981: E/AndroidRuntime(4751):  at android.view.ViewRootImpl$TraversalRunnable.run(ViewRootImpl.java:5670) 
    09-22 20:22:49.981: E/AndroidRuntime(4751):  at android.view.Choreographer$CallbackRecord.run(Choreographer.java:761) 
    09-22 20:22:49.981: E/AndroidRuntime(4751):  at android.view.Choreographer.doCallbacks(Choreographer.java:574) 
    09-22 20:22:49.981: E/AndroidRuntime(4751):  at android.view.Choreographer.doFrame(Choreographer.java:544) 
    09-22 20:22:49.981: E/AndroidRuntime(4751):  at android.view.Choreographer$FrameDisplayEventReceiver.run(Choreographer.java:747) 
    09-22 20:22:49.981: E/AndroidRuntime(4751):  at android.os.Handler.handleCallback(Handler.java:733) 
    09-22 20:22:49.981: E/AndroidRuntime(4751):  at android.os.Handler.dispatchMessage(Handler.java:95) 
    09-22 20:22:49.981: E/AndroidRuntime(4751):  at android.os.Looper.loop(Looper.java:136) 
    09-22 20:22:49.981: E/AndroidRuntime(4751):  at android.app.ActivityThread.main(ActivityThread.java:5017) 
    09-22 20:22:49.981: E/AndroidRuntime(4751):  at java.lang.reflect.Method.invokeNative(Native Method) 
    09-22 20:22:49.981: E/AndroidRuntime(4751):  at java.lang.reflect.Method.invoke(Method.java:515) 
    09-22 20:22:49.981: E/AndroidRuntime(4751):  at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:779) 
    09-22 20:22:49.981: E/AndroidRuntime(4751):  at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:595) 
    09-22 20:22:49.981: E/AndroidRuntime(4751):  at dalvik.system.NativeStart.main(Native Method) 

下面是什么线154指示，和我假设一个类似的问题应该出现的管线155

Location ln; 
    Location lt; 
    double longi=lt.getLongitude(); 
    double lati=ln.getLatitude(); 

    ParseGeoPoint point = new ParseGeoPoint(lati, longi); 
    query.whereWithinKilometers("location", point, 100); 

从本质上讲，我想各地的各种标准为基础，以获取用户，并在此请处理导致问题的位置。

任何帮助将不胜感激。 在此先感谢。

更新：

Location location = new Location(""); // location 
        double lati; // latitude 
        double longi; // longitude 
        lati = location.getLatitude(); 
        longi = location.getLongitude(); 


        ParseGeoPoint point = new ParseGeoPoint(lati, longi); 
        query.whereWithinKilometers("location", point, 100); 

更新2：

我已成功使用抓住该用户的纬度和经度：

@Override 
     public void onLocationChanged(Location userLocation) { 
      // TODO Auto-generated method stub 
      double lati = userLocation.getLatitude(); 
      double longi = userLocation.getLongitude(); 

      } 

问题是掺入当前片段代码这是有问题。

private void setConversationsList() { 
     currentUserId = ParseUser.getCurrentUser().getObjectId(); 


     // String userActivitySelectionName = null; 

     ParseQuery<ParseUser> query = ParseUser.getQuery(); 

     // query.whereEqualTo("ActivityName",userActivitySelectionName); 

     query.whereNotEqualTo("objectId", ParseUser.getCurrentUser() 
       .getObjectId()); 

     query.setLimit(1); 


     Location location = new Location(""); // location 
     double lati; // latitude 
     double longi; // longitude 
     lati = location.getLatitude(); 
     longi = location.getLongitude(); 


     ParseGeoPoint point = new ParseGeoPoint(57, -122); 
     query.whereWithinKilometers("location", point, 1113); 


     query.orderByDescending("Name"); 

     ParseQuery<ParseUser> query1 = ParseUser.getQuery(); 

Answer 1

ctrl-f'ing代码后，我没有找到lt（'lt ='，'lt'或'（lt）'）的任何赋值。在使用它之前，你应该初始化变量。另外，你应该削减不相关的代码部分，这样人们就不必阅读大约200-300行与你的问题无关的代码。

你似乎缺少字段/变量初始化的基本知识，但无论如何，我最近做类似的东西，你可以在这里查看代码：https://github.com/dbarwacz/Beton