Androidのmapviewがクラッシュすることがある（幻影のnullpointerexception）

Question

マップビューでの私の動作がランダムにクラッシュします。私はすべての潜在的なnull変数が10倍のうちの1つが処理されると思いますが、そうではありません。私は私の活動と以下のエラーを付けました。

public class HomeActivity extends MapActivity { 

boolean pickup = false; 

@Override 
public void onCreate(Bundle savedInstanceState) { 
    super.onCreate(savedInstanceState); 
    setContentView(R.layout.home); 

    findViewById(R.id.searchBar).setVisibility(View.VISIBLE); 

    findViewById(R.id.searchBar).setOnClickListener(new OnClickListener(){ 

     @Override 
     public void onClick(View v) { 
      // TODO Auto-generated method stub 

      //load new dialog thing with only a onSearchRequested() thing, and a bg click that finishes the app 

      //but also somehow returns the result back to the map??? put intent, here get intent on resume()?? or whatever, debug breakpoints 
      findViewById(R.id.searchBar).setVisibility(View.GONE); 

      Intent pseudoSearch = new Intent(HomeGroup.group, PseudoMapSearchActivity.class); 
      startActivityForResult(pseudoSearch, 0); 
     } 

    }); 

    // initialize the map and set the default location 
    MapView map = (MapView) findViewById(R.id.map); 
    //map.setBuiltInZoomControls(true); 
    map.setSatellite(false); 


    MapController controller = map.getController(); 
    List<Overlay> overlays = map.getOverlays(); 

    Drawable drawable = this.getResources().getDrawable(
      R.drawable.origin_pin); 
    HomeItemizedOverlay overlay = new HomeItemizedOverlay(drawable, 
      HomeGroup.group); 


    overlays.clear(); 
    overlays.add(overlay); 

    controller.setZoom(17); 
    map.postInvalidate(); 

    final LocationManager locator = (LocationManager) this 
      .getSystemService(Context.LOCATION_SERVICE); 
    String provider = ""; 

    // check what location provider is available 
    if (!locator.isProviderEnabled(LocationManager.GPS_PROVIDER)) { 
     //provider = LocationManager.GPS_PROVIDER; 

     //force user to turn on gps 
     Criteria criteria = new Criteria(); 
     criteria.setAccuracy(Criteria.ACCURACY_FINE); 
     criteria.setPowerRequirement(Criteria.POWER_HIGH); 

     LocationManager lm = (LocationManager)getSystemService(Context.LOCATION_SERVICE); 
     provider = lm.getBestProvider(criteria, true); 
    } else { 
     provider = LocationManager.GPS_PROVIDER; 
    } 

    // get the current location 
    if (provider != null) { 
     //setLocation(locator.getLastKnownLocation(provider)); 

     final LocationListener listener = new LocationListener() { 

      @Override 
      public void onLocationChanged(Location location) { 
       setLocation(location); 
       locator.removeUpdates(this); 
      } 

      @Override 
      public void onProviderDisabled(String provider) { 
      } 

      @Override 
      public void onProviderEnabled(String provider) { 
      } 

      @Override 
      public void onStatusChanged(String provider, int status, 
        Bundle extras) { 
      } 
     }; 

     locator.requestLocationUpdates(provider, 15000, 0, listener); 
    } else { 
     Toast toast = Toast.makeText(HomeActivity.this, 
       "Location provider could not be found.", Toast.LENGTH_LONG); 
     toast.show(); 
    } 

} 

/** 
* Performs any action required to update the current location displayed on 
* the home map. 
* 
* @param location 
*   A {@link Location} object with the new location to display. 
*/ 
private void setLocation(Location location) { 

    if (location == null) { 
     return; 
    } 

    if(AndroidHelper.pickup == false) 
    { 
     MapView map = (MapView) findViewById(R.id.map); 
     map.setSatellite(false); 

     MapController controller = map.getController(); 
     List<Overlay> overlays = map.getOverlays(); 

     Drawable drawable = this.getResources().getDrawable(
      R.drawable.origin_pin); 
     HomeItemizedOverlay overlay = new HomeItemizedOverlay(drawable, 
      HomeGroup.group); 

     int latitude = (int) (location.getLatitude() * 1e6); 
     int longitude = (int) (location.getLongitude() * 1e6); 

     GeoPoint point = new GeoPoint(latitude, longitude); 
     if(point!=null) 
     { 
      OverlayItem item = new OverlayItem(point, "Current Location", 
        "This is where you are currently located."); 
      overlay.setOrigin(item); 
     } 
     overlays.clear(); 
     overlays.add(overlay); 

     controller.animateTo(point); 
     controller.setZoom(18); 
     map.postInvalidate(); 
    } 



} 

は、ここでは、このlogcatエラーが私のコードの行を言及していないので、それが破壊された場合、私は本当に理解していない私のHomeItemizedOverlayクラス

public class HomeItemizedOverlay extends ItemizedOverlay<OverlayItem> { 

    private Map<Integer, OverlayItem> overlays = null; 
    private Context context = null; 

    private static final int ORIGIN = 0; 
    private static final int DESTINATION = 1; 

    public HomeItemizedOverlay(Drawable defaultMarker) { 
      super(boundCenterBottom(defaultMarker)); 
      this.overlays = new HashMap<Integer, OverlayItem>(); 
    } 

    public HomeItemizedOverlay(Drawable defaultMarker, Context context) { 
      this(defaultMarker); 
      this.context = context; 
    } 

    /** 
    * Set an {@link OverlayItem} to be the origin and calls {@link #populate()} 
    * to create the overlay. 
    * 
    * @param item 
    *   An item to add to the overlay. 
    */ 
    public void setOrigin(OverlayItem item) { 
      this.overlays.put(ORIGIN, item); 
      populate(); 
    } 

    /** 
    * Adds an {@link OverlayItem} to be the destination and calls 
    * {@link #populate()} to create the overlay. 
    * 
    * @param item 
    *   An item to add to the overlay. 
    */ 
    public void setDestination(OverlayItem item) { 
      this.overlays.put(DESTINATION, item); 
      populate(); 
    } 

    @Override 
    protected OverlayItem createItem(int i) { 
      return this.overlays.get(i); 
    } 

    @Override 
    public int size() { 
      return this.overlays.size(); 
    } 

    @Override 
    protected boolean onTap(int index) { 
      OverlayItem item = this.overlays.get(index); 

      //think this causes crashes 
      AlertDialog.Builder dialog = new AlertDialog.Builder(this.context); 
      dialog.setTitle(item.getTitle()); 
      dialog.setMessage(item.getSnippet()); 
      dialog.show(); 

      return true; 
    } 
} 

です。これは10回中1回発生します。

11-15 13:47:13.192: E/AndroidRuntime(3585): FATAL EXCEPTION: main 
11-15 13:47:13.192: E/AndroidRuntime(3585): java.lang.NullPointerException 
11-15 13:47:13.192: E/AndroidRuntime(3585):  at com.google.android.maps.ItemizedOverlay.getItemsAtLocation(ItemizedOverlay.java:617) 
11-15 13:47:13.192: E/AndroidRuntime(3585):  at com.google.android.maps.ItemizedOverlay.getItemAtLocation(ItemizedOverlay.java:586) 
11-15 13:47:13.192: E/AndroidRuntime(3585):  at com.google.android.maps.ItemizedOverlay.handleMotionEvent(ItemizedOverlay.java:498) 
11-15 13:47:13.192: E/AndroidRuntime(3585):  at com.google.android.maps.ItemizedOverlay.onTouchEvent(ItemizedOverlay.java:572) 
11-15 13:47:13.192: E/AndroidRuntime(3585):  at com.google.android.maps.OverlayBundle.onTouchEvent(OverlayBundle.java:63) 
11-15 13:47:13.192: E/AndroidRuntime(3585):  at com.google.android.maps.MapView.onTouchEvent(MapView.java:679) 
11-15 13:47:13.192: E/AndroidRuntime(3585):  at android.view.View.dispatchTouchEvent(View.java:3882) 
11-15 13:47:13.192: E/AndroidRuntime(3585):  at android.view.ViewGroup.dispatchTouchEvent(ViewGroup.java:903) 
11-15 13:47:13.192: E/AndroidRuntime(3585):  at android.view.ViewGroup.dispatchTouchEvent(ViewGroup.java:869) 
11-15 13:47:13.192: E/AndroidRuntime(3585):  at android.view.ViewGroup.dispatchTouchEvent(ViewGroup.java:869) 
11-15 13:47:13.192: E/AndroidRuntime(3585):  at android.view.ViewGroup.dispatchTouchEvent(ViewGroup.java:869) 
11-15 13:47:13.192: E/AndroidRuntime(3585):  at com.android.internal.policy.impl.PhoneWindow$DecorView.superDispatchTouchEvent(PhoneWindow.java:1691) 
11-15 13:47:13.192: E/AndroidRuntime(3585):  at com.android.internal.policy.impl.PhoneWindow.superDispatchTouchEvent(PhoneWindow.java:1125) 
11-15 13:47:13.192: E/AndroidRuntime(3585):  at android.app.Activity.dispatchTouchEvent(Activity.java:2096) 
11-15 13:47:13.192: E/AndroidRuntime(3585):  at com.android.internal.policy.impl.PhoneWindow$DecorView.dispatchTouchEvent(PhoneWindow.java:1675) 
11-15 13:47:13.192: E/AndroidRuntime(3585):  at android.view.ViewGroup.dispatchTouchEvent(ViewGroup.java:869) 
11-15 13:47:13.192: E/AndroidRuntime(3585):  at android.view.ViewGroup.dispatchTouchEvent(ViewGroup.java:869) 
11-15 13:47:13.192: E/AndroidRuntime(3585):  at com.android.internal.policy.impl.PhoneWindow$DecorView.superDispatchTouchEvent(PhoneWindow.java:1691) 
11-15 13:47:13.192: E/AndroidRuntime(3585):  at com.android.internal.policy.impl.PhoneWindow.superDispatchTouchEvent(PhoneWindow.java:1125) 
11-15 13:47:13.192: E/AndroidRuntime(3585):  at android.app.Activity.dispatchTouchEvent(Activity.java:2096) 
11-15 13:47:13.192: E/AndroidRuntime(3585):  at com.android.internal.policy.impl.PhoneWindow$DecorView.dispatchTouchEvent(PhoneWindow.java:1675) 
11-15 13:47:13.192: E/AndroidRuntime(3585):  at android.view.ViewGroup.dispatchTouchEvent(ViewGroup.java:869) 
11-15 13:47:13.192: E/AndroidRuntime(3585):  at android.view.ViewGroup.dispatchTouchEvent(ViewGroup.java:869) 
11-15 13:47:13.192: E/AndroidRuntime(3585):  at android.view.ViewGroup.dispatchTouchEvent(ViewGroup.java:869) 
11-15 13:47:13.192: E/AndroidRuntime(3585):  at android.view.ViewGroup.dispatchTouchEvent(ViewGroup.java:869) 
11-15 13:47:13.192: E/AndroidRuntime(3585):  at android.view.ViewGroup.dispatchTouchEvent(ViewGroup.java:869) 
11-15 13:47:13.192: E/AndroidRuntime(3585):  at com.android.internal.policy.impl.PhoneWindow$DecorView.superDispatchTouchEvent(PhoneWindow.java:1691) 
11-15 13:47:13.192: E/AndroidRuntime(3585):  at com.android.internal.policy.impl.PhoneWindow.superDispatchTouchEvent(PhoneWindow.java:1125) 
11-15 13:47:13.192: E/AndroidRuntime(3585):  at android.app.Activity.dispatchTouchEvent(Activity.java:2096) 
11-15 13:47:13.192: E/AndroidRuntime(3585):  at com.android.internal.policy.impl.PhoneWindow$DecorView.dispatchTouchEvent(PhoneWindow.java:1675) 
11-15 13:47:13.192: E/AndroidRuntime(3585):  at android.view.ViewRoot.deliverPointerEvent(ViewRoot.java:2204) 
11-15 13:47:13.192: E/AndroidRuntime(3585):  at android.view.ViewRoot.handleMessage(ViewRoot.java:1888) 
11-15 13:47:13.192: E/AndroidRuntime(3585):  at android.os.Handler.dispatchMessage(Handler.java:99) 
11-15 13:47:13.192: E/AndroidRuntime(3585):  at android.os.Looper.loop(Looper.java:130) 
11-15 13:47:13.192: E/AndroidRuntime(3585):  at android.app.ActivityThread.main(ActivityThread.java:3683) 
11-15 13:47:13.192: E/AndroidRuntime(3585):  at java.lang.reflect.Method.invokeNative(Native Method) 
11-15 13:47:13.192: E/AndroidRuntime(3585):  at java.lang.reflect.Method.invoke(Method.java:507) 
11-15 13:47:13.192: E/AndroidRuntime(3585):  at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:839) 
11-15 13:47:13.192: E/AndroidRuntime(3585):  at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:597) 
11-15 13:47:13.192: E/AndroidRuntime(3585):  at dalvik.system.NativeStart.main(Native Method) 

Answer 1

あなたのコンストラクタでsuperを呼び出した直後にpopulate()を呼び出してみてください。このような問題の他の苦情があったhttp://code.google.com/p/android/issues/detail?id=2035。

populateのjavadocは言う：新しいItemizedOverlay上のすべての処理を実行する

ユーティリティメソッドを。サブクラスは、createItem（int）メソッドを通じてItemsを提供します。サブクラスはデータがあるとすぐにこれを呼び出す必要があります。

これは正直なところ大したことではありませんが、コンストラクタでこのメソッドを呼び出す必要があると思います。