title: How to get only new items with addValueEventListener
body: <p>When a child gets added into my firebase it Logs all the Annotation_City's in my firebase again. How can I get it to only print the new Annotation_City that got added?</p>
  
  <pre><code>public void AllLocationMarkers() {
          grabMarkersFromDb = new Firebase("***");
          grabMarkersFromDb.addValueEventListener(new ValueEventListener() {
              @Override
              public void onDataChange(DataSnapshot dataSnapshot) {
                  for (DataSnapshot locationSnapshot : dataSnapshot.getChildren()) {
                      String city_Name = (String) locationSnapshot.child("Annotation_City").getValue();
                      Log.d("City updated", "city: " + city_Name);
                  }
              }
  
              @Override
              public void onCancelled(FirebaseError firebaseError) {
  
              }
          });
      }
  </code></pre>