SimpleCursor的NullPointerExeption adapter.Works与onLocationChanged（）

Question

我有一个数据库的地方和他们的坐标。我想创建一个片段，在那里我会列出更多5公里以上的地方。我的代码是：

我从明年开始片段：

 case R.id.btn_near: 
     if(isOnline()){ 
     ft = getSupportFragmentManager().beginTransaction().replace(
      R.id.content_frame, frg); 
     ft.commit(); 
     } 
     else 
      Toast.makeText(this, "Подключите интернет", 1000).show(); 
     break; 

FragmentNear.class

public class FragmentNear extends Fragment implements 
    android.location.LocationListener { 
Cursor c; 
View v; 
ListView lvMore5; 
Database db; 
protected LocationManager locationManager; 
String lat; 
String provider; 
protected String latitude, longitude; 
protected boolean gps_enabled, network_enabled; 
double myLat, myLong; 
SimpleCursorAdapter scAdapter; 
String[] from; 
int[] to; 

@Override 
public View onCreateView(LayoutInflater inflater, ViewGroup container, 
     Bundle savedInstanceState) { 
    Log.d("myLogs", "-------- onCreateView " + myLat + " " + myLong); 
    v = inflater.inflate(R.layout.fragment_near, null); 
    lvMore5 = (ListView) v.findViewById(R.id.lv_more_5); 
    Log.d("myLogs", "-------- onCreateViewEnd " + myLat + " " + myLong); 
    return v; 
} 

@Override 
public void onResume() { 
    db = new Database(getActivity()); 
    db.open(); 
    from = new String[] { Database.PLACE_NAME, Database.PLACE_DISTANCE, 
      Database.PLACE_ADRESS }; 
    to = new int[] { R.id.tv_place_name_n, R.id.tv_distance, 
      R.id.tv_place_adress_n }; 
    Log.d("myLogs", "-------- onCreate " + myLat + " " + myLong); 
    locationManager = (LocationManager) getActivity().getSystemService(
      Context.LOCATION_SERVICE); 
    locationManager.requestLocationUpdates(
      LocationManager.NETWORK_PROVIDER, 0, 0, this); 
    super.onResume(); 
} 

public double getDistance(double myLat, double myLong, double pointLat, 
     double pointLong) { 
    Log.d("myLogs", "getDistance =" + myLat + " " + myLong); 
    double distance = 0; 
    Location locationA = new Location("A"); 
    // 69.019207,33.085015", 
    locationA.setLatitude(myLat); 
    locationA.setLongitude(myLong); 
    Location locationB = new Location("B"); 
    locationB.setLatitude(pointLat); 
    locationB.setLongitude(pointLong); 
    distance = locationA.distanceTo(locationB); 
    return distance/1000; 

} 

@Override 
public void onLocationChanged(Location location) { 
    final Location loc = location; 
    myLat = loc.getLatitude(); 
    myLong = location.getLongitude(); 
    Log.d("myLogs", "-------- onLoChangedEnd " + myLat + " " + myLong); 
    calculateDistance();---I want to calculate distance after i get my location 

} 

@Override 
public void onStop() { 
    db.close(); 
    if (c != null) { 
     c.close(); 
    } 
    super.onStop(); 
} 

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

} 

public void calculateDistance() { 
    c = db.getPlaceByGroup(3); 
    if (c != null) { 
     if (c.moveToFirst()) { 

      do { 

       String s = c.getString(8); 
       double lat, lon; 
       lat = Double.valueOf(s.substring(0, s.indexOf(","))); 
       lon = Double.valueOf(s.substring(s.indexOf(",") + 1, 
         s.length())); 

       Log.d("myLogs", 
         "id= " + c.getInt(0) + "Coordinates" 
           + c.getString(8));// !! 

       ContentValues cv = new ContentValues(); 
       cv.put(Database.PLACE_DISTANCE, 
         getDistance(myLat, myLong, lat, lon)); 
       int updCount = db.mDB.update(Database.DB_TABLE_PLACES, cv, 
         "_id = " + db.getPlaceId(3, c.getPosition()), null); 
       Log.d("myLogs", "updated rows count = " + updCount); 

      } while (c.moveToNext()); 
      // Log.d("myLogs","N1ame =" +c.getString(1)); 
     } 
    } else 
     Log.d("myLogs", "Cursor is null"); 


    c = db.getPlacesMore5000(); 
    scAdapter = new SimpleCursorAdapter(getActivity(), 
      R.layout.item_near_list, c, from, to); 
    lvMore5.setCacheColorHint(Color.TRANSPARENT); 
    lvMore5.setAdapter(scAdapter); 
    lvMore5.setOnTouchListener(new ListView.OnTouchListener() { 

     @Override 
     public boolean onTouch(View v, MotionEvent event) { 
      int action = event.getAction(); 
      switch (action) { 
      case MotionEvent.ACTION_DOWN: 
       // Disallow ScrollView to intercept touch events. 
       v.getParent().requestDisallowInterceptTouchEvent(true); 
       break; 

      case MotionEvent.ACTION_UP: 
       // Allow ScrollView to intercept touch events. 
       v.getParent().requestDisallowInterceptTouchEvent(false); 
       break; 
      } 

      // Handle ListView touch events. 
      v.onTouchEvent(event); 
      return true; 
     } 
    }); 
    lvMore5.setOnItemClickListener(new OnItemClickListener() { 

     @Override 
     public void onItemClick(AdapterView<?> parent, View view, 
       int position, long id) { 
      Fragment fragment = new FragmentPlaceInfo(); 
      db.open(); 
      Bundle data = new Bundle(); 
      c = db.getPlacesMore5000(); 
      if (c != null) { 
       c.moveToPosition(position); 
       data.putInt("placeId", c.getInt(0)); 
      } else 
       Log.d("myLogs", "Cursor is null"); 

      fragment.setArguments(data); 
      FragmentTransaction transaction = getFragmentManager() 
        .beginTransaction(); 

      transaction.replace(R.id.content_frame, fragment); 
      transaction.addToBackStack(null); 
      transaction.commit(); 

      // /less 1 

     } 

    }); 
} 

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

} 

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

} 

} 

真实的设备 - wgen我按R.id.btn_near - 一切都很好，当我按下它再次（我想再次运行片段） - 我在这一行取得错误

08-23 17:52:39.928: E/AndroidRuntime(2953): FATAL EXCEPTION: main 
08-23 17:52:39.928: E/AndroidRuntime(2953): java.lang.NullPointerException 
08-23 17:52:39.928: E/AndroidRuntime(2953):  at android.support.v4.widget.ResourceCursorAdapter.<init>(ResourceCursorAdapter.java:56) 
08-23 17:52:39.928: E/AndroidRuntime(2953):  at android.support.v4.widget.SimpleCursorAdapter.<init>(SimpleCursorAdapter.java:63) 
08-23 17:52:39.928: E/AndroidRuntime(2953):  at com.example.cars51ru.FragmentNear.showMFD(FragmentNear.java:352) 
08-23 17:52:39.928: E/AndroidRuntime(2953):  at com.example.cars51ru.FragmentNear.onLocationChanged(FragmentNear.java:124) 
08-23 17:52:39.928: E/AndroidRuntime(2953):  at android.location.LocationManager$ListenerTransport._handleMessage(LocationManager.java:227) 
08-23 17:52:39.928: E/AndroidRuntime(2953):  at android.location.LocationManager$ListenerTransport.access$000(LocationManager.java:160) 
08-23 17:52:39.928: E/AndroidRuntime(2953):  at android.location.LocationManager$ListenerTransport$1.handleMessage(LocationManager.java:176) 
08-23 17:52:39.928: E/AndroidRuntime(2953):  at android.os.Handler.dispatchMessage(Handler.java:99) 
08-23 17:52:39.928: E/AndroidRuntime(2953):  at android.os.Looper.loop(Looper.java:123) 
08-23 17:52:39.928: E/AndroidRuntime(2953):  at android.app.ActivityThread.main(ActivityThread.java:3839) 
08-23 17:52:39.928: E/AndroidRuntime(2953):  at java.lang.reflect.Method.invokeNative(Native Method) 
08-23 17:52:39.928: E/AndroidRuntime(2953):  at java.lang.reflect.Method.invoke(Method.java:507) 
08-23 17:52:39.928: E/AndroidRuntime(2953):  at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:841) 
08-23 17:52:39.928: E/AndroidRuntime(2953):  at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:599) 
08-23 17:52:39.928: E/AndroidRuntime(2953):  at dalvik.system.NativeStart.main(Native Method) 

：scAdapter = new SimpleCursorAdapter(getActivity(), R.layout.item_near_list, c, from, to);

当我在模拟器上启动它时 - 我得到空的listView。

Answer 1

尝试从投入和公正适配器的初始化之前，像这样：

db = new Database(getActivity()); 
db.open(); 
from = new String[] { Database.PLACE_NAME, Database.PLACE_DISTANCE, 
     Database.PLACE_ADRESS }; 
to = new int[] { R.id.tv_place_name_n, R.id.tv_distance, 
     R.id.tv_place_adress_n }; 
c = db.getPlacesMore5000(); 
scAdapter = new SimpleCursorAdapter(getActivity(), 
     R.layout.item_near_list, c, from, to);