Question

我有一个排行榜，可以找回前十名球员。数据在第一次调用时正确显示，但每当onPause / onStop然后onResume / onStart被调用时，数据就不再按其排序顺序显示，就好像orderByValue()方法被忽略一样。我在onStart()方法上附加了侦听器，并在onStop()方法中将其删除。这让我发疯了。

 //get the active week id to use for reference
String week_id = getActivity().getSharedPreferences(Constants.getPreferenceFile(),
  Context.MODE_PRIVATE).getString(Constants.getActiveWeek(),null);
//initialize the database references
if(leader_board_child_event_listener == null) {
  leader_board_reference = MainActivity.firebaseDatabase.getRef().child(Constants.getLeaderBoardChild());
  user_reference = MainActivity.firebaseDatabase.getRef().child(Constants.getUsersChild());
  Log.d(TAG, "sorting the query first");
  leader_board_query = leader_board_reference.child(week_id).orderByValue().limitToLast(10);

  leader_board_child_event_listener = new ChildEventListener() {
    @Override
    public void onChildAdded(final DataSnapshot dataSnapshot, String s) {
      Log.d(TAG, "child added == " + dataSnapshot.getValue());
      //get the user details every time child added is called
      user_reference.addListenerForSingleValueEvent(new ValueEventListener() {
        @Override
        public void onDataChange(DataSnapshot dataSnapshot2) {
          hideProgressBar();
          //add the user details to a list
          user_list.add(new User(dataSnapshot.getKey(), dataSnapshot2.child(dataSnapshot.getKey()).
            child(Constants.getUserNameChild()).getValue(String.class), dataSnapshot2.
            child(dataSnapshot.getKey()).child(Constants.getProfilePicUriChild()).getValue(String.class),
            dataSnapshot.getValue(double.class)));
          //update the recyclerview adapter with each addition
          board_adapter.notifyDataSetChanged();
          Log.d(TAG, "user details: " + user_list.size());
        }

        @Override
        public void onCancelled(DatabaseError databaseError) {
        }
      });
    }

    @Override
    public void onChildChanged(DataSnapshot dataSnapshot, String s) {

    }

    @Override
    public void onChildRemoved(DataSnapshot dataSnapshot) {

    }

    @Override
    public void onChildMoved(DataSnapshot dataSnapshot, String s) {

    }

    @Override
    public void onCancelled(DatabaseError databaseError) {

    }
  };
}
//add the listener to leader board database reference
leader_board_query.addChildEventListener(leader_board_child_event_listener);

我做错了什么？

Android Firebase会忽略orderByValue（）

0 个答案: