title: Condition to notifyDataSetChanged to adapter when onGeoQueryReady
body: <p>a little question about the correct approach when dealing with geoQueries and adapters.</p>
  
  <p>I have a list of users keys in a GeoQuery database (with coordinates obviously), and I would like to display them in a ListView when they enter in a certain range.</p>
  
  <p>Here's some code.</p>
  
  <pre><code>    usersGeoQuery.addGeoQueryEventListener(new GeoQueryEventListener() {
  
          @Override
          public void onKeyEntered(String key, GeoLocation location) {
  
              firebaseDatabase.getReference("users").child(key).addListenerForSingleValueEvent(new ValueEventListener() {
                  @Override
                  public void onDataChange(DataSnapshot dataSnapshot) {
                      User user = dataSnapshot.getValue(User.class);
                      users.add(user);
                      // if ( ??? ) 
                      mAdapter.notifyDataSetChanged();
                  }
  
                  @Override
                  public void onCancelled(DatabaseError databaseError) {
  
                  }
              });
          }
  
          @Override
          public void onKeyExited(String key) {
              for(Iterator&lt;User&gt; it = users.iterator(); it.hasNext();){
                  User user = it.next();
                  if(user.id == key){
                      it.remove();
                  }
              }
              // if ( ??? )
              mAdapter.notifyDataSetChanged();
          }
  
          @Override
          public void onKeyMoved(String key, GeoLocation location) { }
  
          @Override
          public void onGeoQueryReady() { 
              // this actually triggers before firebase listeners
          }
  
          @Override
          public void onGeoQueryError(DatabaseError error) {
          }
      });
  </code></pre>
  
  <p>Actually, this works, but, of course, it notifies changes to the adapter everytime a entry it's added to the list. So it's not good for performance.</p>
  
  <p>Any suggestion for a smart approach about this?</p>
  
  <p>Thanks!</p>