删除ChildEventListener [英] Removing ChildEventListener

问题描述

我正在使用Firebase childEventListener，将它添加到Node中N次，以便从数据库中获取数据.

I'm using Firebase childEventListener which is added N-number of times to a Node to get data from the DB.

现在，我正在尝试删除childEventListener，它似乎不起作用，并且我得到了重复的数据.

Now I'm trying to remove the childEventListener and it does not seem to work and I get duplicate data.

    query = FirebaseDatabase.getInstance().getReference()
            .child("chat")
            .child("room-messages")
            .child(roomID)
            .orderByChild("timestamp")
            .limitToLast(index);

    paginationListener = query.addChildEventListener(new ChildEventListener() {
        @Override
        public void onChildAdded(DataSnapshot dataSnapshot, String s) {
            Log.d(TAG, dataSnapshot.getKey() + " - Single Value");
            try {
                Message message = dataSnapshot.getValue(Message.class);
                message.setId(dataSnapshot.getKey());
                EventBus.getDefault().post(new GetPaginatedMessage(message));
            } catch (RuntimeException e) {
                Log.d(TAG, "Type Cast Exception Caught");
            }

        }

并像这样删除监听器

 if (query != null && paginationListener != null) {
        query.removeEventListener(paginationListener);
    }

它似乎不起作用，并且我得到重复的数据. 任何帮助都可以申请

It doesn't seem to work and I get duplicate data. Any help is appriciated

推荐答案

调用removeEventListener()会将侦听器从该位置删除.调用后，它将不会为接收到的任何数据触发事件.它可能仍会为已接收到的数据触发一些事件.

Calling removeEventListener() removes the listener from that location. It will not fire events for any data received after you call it. It may still fire some events for data it's already received.

Jonny对firebase-talk组的回答关于同样的行为:

事件被异步排队，并且可能在其他线程上运行，因此在调用removeEventListener之前，可能已经有排队的事件.

events are queued up asynchronously and potentially run on a different thread, so there might have been events queued up before you call removeEventListener.

这篇关于删除ChildEventListener的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！