title: Observer was not registered. ListView Adapter crashing sometime
body: <p>I have a service that is downloading some photos album data and there is a Activity. The serveice has a reference of Activity and calls method of the activity notifying the UI to show latest list data that is in queue. The service calls an activity-method that has as handler to update UI e.g</p>
  
  <pre><code>public void askForChecheList ( ) {
      galleryHandler.sendEmptyMessage ( 5 ) ;
  }
  </code></pre>
  
  <p>Where handler is like</p>
  
  <pre><code>private Handler galleryHandler = new Handler() {
      @ Override
      public void handleMessage (Message msg) {
          // ...
          if ( msg.what == 5 ) {
              showUpdatedList ( ) ;
          }
      }
  };
  </code></pre>
  
  <p>I am updating listView item with following code:</p>
  
  <pre><code>private synchronized void showUpdatedList ( ) {
  
      try {
  
          checkForPhotoService ( ) ;
          if ( mPhotoSyncService != null ) {
              this.mAllAlbumsData = mPhotoSyncService.getSyncAlbumsList ( ) ;
          }
          if ( mAlbumQueuedListAdapter == null ) {
              mAlbumQueuedListAdapter = new AlbumQueueListAdapter ( mContext , mAllAlbumsData ) ;
              mQueuedListView.setAdapter ( mAlbumQueuedListAdapter ) ;
          } else {
              mAlbumQueuedListAdapter.setData ( mAllAlbumsData ) ;
              mAlbumQueuedListAdapter.notifyDataSetChanged ( );
          }
      } catch ( Exception e ) {
          e.printStackTrace ( ) ;
      }
  }
  </code></pre>
  
  <p>But Don't know sometime it crash the application with this log. I have a very good experience of using listView , Adapter but I am getting this error first time. Did anyone experience that do? </p>
  
  <pre><code>01-19 23:21:01.139: W/System.err(13013): java.lang.IllegalStateException: Observer android.widget.AbsListView$AdapterDataSetObserver@413afb00 was not registered.
  01-19 23:21:01.139: W/System.err(13013): at android.database.Observable.unregisterObserver(Observable.java:69)
  01-19 23:21:01.139: W/System.err(13013): at android.widget.BaseAdapter.unregisterDataSetObserver(BaseAdapter.java:42)
  01-19 23:21:01.139: W/System.err(13013): at android.widget.ListView.setAdapter(ListView.java:556)
  01-19 23:21:01.139: W/System.err(13013): at au.com.apparitionimaging.photosuitcase.activities.StatusActivity.showUpdatedList(StatusActivity.java:326)
  01-19 23:21:01.139: W/System.err(13013): at au.com.apparitionimaging.photosuitcase.activities.StatusActivity.getCachedList(StatusActivity.java:228)
  01-19 23:21:01.139: W/System.err(13013): at au.com.apparitionimaging.photosuitcase.activities.PhotoSyncService.downloadAlbums(PhotoSyncService.java:540)
  01-19 23:21:01.144: W/System.err(13013): at au.com.apparitionimaging.photosuitcase.activities.PhotoSyncService.onHandleIntent(PhotoSyncService.java:111)
  01-19 23:21:01.144: W/System.err(13013): at android.app.IntentService$ServiceHandler.handleMessage(IntentService.java:65)
  01-19 23:21:01.144: W/System.err(13013): at android.os.Handler.dispatchMessage(Handler.java:99)
  01-19 23:21:01.144: W/System.err(13013): at android.os.Looper.loop(Looper.java:155)
  01-19 23:21:01.144: W/System.err(13013): at android.os.HandlerThread.run(HandlerThread.java:60)
  01-19 23:21:01.174: W/System.err(13013): java.lang.IllegalStateException: Observer android.widget.AbsListView$AdapterDataSetObserver@413afb00 was not registered.
  01-19 23:21:01.174: W/System.err(13013): at android.database.Observable.unregisterObserver(Observable.java:69)
  01-19 23:21:01.174: W/System.err(13013): at android.widget.BaseAdapter.unregisterDataSetObserver(BaseAdapter.java:42)
  01-19 23:21:01.174: W/System.err(13013): at android.widget.ListView.setAdapter(ListView.java:556)
  01-19 23:21:01.174: W/System.err(13013): at au.com.apparitionimaging.photosuitcase.activities.StatusActivity.showUpdatedList(StatusActivity.java:326)
  01-19 23:21:01.174: W/System.err(13013): at au.com.apparitionimaging.photosuitcase.activities.StatusActivity.getCachedList(StatusActivity.java:228)
  01-19 23:21:01.174: W/System.err(13013): at au.com.apparitionimaging.photosuitcase.activities.StatusActivity.showUpdatedValues(StatusActivity.java:275)
  01-19 23:21:01.174: W/System.err(13013): at au.com.apparitionimaging.photosuitcase.activities.StatusActivity.access$4(StatusActivity.java:259)
  01-19 23:21:01.174: W/System.err(13013): at au.com.apparitionimaging.photosuitcase.activities.StatusActivity$2.handleMessage(StatusActivity.java:93)
  01-19 23:21:01.174: W/System.err(13013): at android.os.Handler.dispatchMessage(Handler.java:99)
  01-19 23:21:01.174: W/System.err(13013): at android.os.Looper.loop(Looper.java:155)
  01-19 23:21:01.174: W/System.err(13013): at android.app.ActivityThread.main(ActivityThread.java:5485)
  01-19 23:21:01.174: W/System.err(13013): at java.lang.reflect.Method.invokeNative(Native Method)
  01-19 23:21:01.174: W/System.err(13013): at java.lang.reflect.Method.invoke(Method.java:511)
  01-19 23:21:01.174: W/System.err(13013): at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:1028)
  01-19 23:21:01.174: W/System.err(13013): at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:795)
  01-19 23:21:01.174: W/System.err(13013): at dalvik.system.NativeStart.main(Native Method)
  01-19 23:21:01.174: W/System.err(13013): java.lang.IllegalStateException: Observer android.widget.AbsListView$AdapterDataSetObserver@413afb00 was not registered.
  01-19 23:21:01.174: W/System.err(13013): at android.database.Observable.unregisterObserver(Observable.java:69)
  01-19 23:21:01.174: W/System.err(13013): at android.widget.BaseAdapter.unregisterDataSetObserver(BaseAdapter.java:42)
  01-19 23:21:01.174: W/System.err(13013): at android.widget.ListView.setAdapter(ListView.java:556)
  01-19 23:21:01.174: W/System.err(13013): at au.com.apparitionimaging.photosuitcase.activities.StatusActivity.showUpdatedList(StatusActivity.java:326)
  01-19 23:21:01.174: W/System.err(13013): at au.com.apparitionimaging.photosuitcase.activities.StatusActivity.getCachedList(StatusActivity.java:228)
  01-19 23:21:01.174: W/System.err(13013): at au.com.apparitionimaging.photosuitcase.activities.StatusActivity.showUpdatedValues(StatusActivity.java:275)
  01-19 23:21:01.174: W/System.err(13013): at au.com.apparitionimaging.photosuitcase.activities.StatusActivity.access$4(StatusActivity.java:259)
  01-19 23:21:01.174: W/System.err(13013): at au.com.apparitionimaging.photosuitcase.activities.StatusActivity$2.handleMessage(StatusActivity.java:93)
  01-19 23:21:01.174: W/System.err(13013): at android.os.Handler.dispatchMessage(Handler.java:99)
  01-19 23:21:01.174: W/System.err(13013): at android.os.Looper.loop(Looper.java:155)
  01-19 23:21:01.174: W/System.err(13013): at android.app.ActivityThread.main(ActivityThread.java:5485)
  01-19 23:21:01.174: W/System.err(13013): at java.lang.reflect.Method.invokeNative(Native Method)
  01-19 23:21:01.174: W/System.err(13013): at java.lang.reflect.Method.invoke(Method.java:511)
  01-19 23:21:01.174: W/System.err(13013): at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:1028)
  01-19 23:21:01.174: W/System.err(13013): at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:795)
  01-19 23:21:01.174: W/System.err(13013): at dalvik.system.NativeStart.main(Native Method)
  01-19 23:21:02.589: W/System.err(13013): java.lang.IllegalStateException: Observer android.widget.AbsListView$AdapterDataSetObserver@413afb00 was not registered.
  01-19 23:21:02.609: W/System.err(13013): at android.database.Observable.unregisterObserver(Observable.java:69)
  01-19 23:21:02.609: W/System.err(13013): at android.widget.BaseAdapter.unregisterDataSetObserver(BaseAdapter.java:42)
  01-19 23:21:02.609: W/System.err(13013): at android.widget.ListView.setAdapter(ListView.java:556)
  01-19 23:21:02.609: W/System.err(13013): at au.com.apparitionimaging.photosuitcase.activities.StatusActivity.showUpdatedList(StatusActivity.java:326)
  01-19 23:21:02.619: W/System.err(13013): at au.com.apparitionimaging.photosuitcase.activities.StatusActivity.getCachedList(StatusActivity.java:228)
  01-19 23:21:02.619: W/System.err(13013): at au.com.apparitionimaging.photosuitcase.activities.StatusActivity$2.handleMessage(StatusActivity.java:97)
  01-19 23:21:02.619: W/System.err(13013): at android.os.Handler.dispatchMessage(Handler.java:99)
  01-19 23:21:02.629: W/System.err(13013): at android.os.Looper.loop(Looper.java:155)
  01-19 23:21:02.629: W/System.err(13013): at android.app.ActivityThread.main(ActivityThread.java:5485)
  01-19 23:21:02.629: W/System.err(13013): at java.lang.reflect.Method.invokeNative(Native Method)
  01-19 23:21:02.629: W/System.err(13013): at java.lang.reflect.Method.invoke(Method.java:511)
  01-19 23:21:02.629: W/System.err(13013): at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:1028)
  01-19 23:21:02.629: W/System.err(13013): at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:795)
  01-19 23:21:02.629: W/System.err(13013): at dalvik.system.NativeStart.main(Native Method)
  </code></pre>