Question

我正在使用firebase作为后端制作聊天应用程序。目前，我在设置用于在RecyclerView中发送和接收消息的项目布局时遇到问题。当我为发送和接收消息使用相同的项目布局时，它完美地工作。但是我想将屏幕分为两部分左侧用于发送消息，右侧用于接收消息。制作FirebaseRecyclerAdapter对象时，我只能传递一个布局作为参数。我真的在努力解决这个问题。希望有人帮助我。

private void loadMessages() {

    mAdapter = new FirebaseRecyclerAdapter<MessageToSend, NewMessageViewHolder>(
            MessageToSend.class,
            R.layout.single_message_new,
            NewMessageViewHolder.class,
            messageRef.child(sender).child(receiver)
    ) {
        @TargetApi(Build.VERSION_CODES.M)
        @Override
        protected void populateViewHolder(NewMessageViewHolder viewHolder, MessageToSend model, int position) {
            if (sender.equals(model.getSender())) {

                viewHolder.outMessage.setTextColor(getResources().getColor(R.color.darkGreen));
            }
            else {
                viewHolder.outMessage.setTextColor(Color.BLACK);
                //viewHolder.outMessage.setGravity(Gravity.RIGHT);
            }
            viewHolder.outMessage.setText(model.getMessage());
            viewHolder.sender.setText(model.getSender());
        }
    };

    mAdapter.registerAdapterDataObserver(new RecyclerView.AdapterDataObserver() {
        @Override
        public void onItemRangeInserted(int positionStart, int itemCount) {
            super.onItemRangeInserted(positionStart, itemCount);
            int friendlyMessageCount = mAdapter.getItemCount();
            int lastVisiblePosition = mLinearlayoutManager.findLastCompletelyVisibleItemPosition();
            // If the recycler view is initially being loaded or the user is at the bottom of the list, scroll
            // to the bottom of the list to show the newly added message.
            if (lastVisiblePosition == -1 ||
                    (positionStart >= (friendlyMessageCount - 1) && lastVisiblePosition == (positionStart - 1))) {
                recyclerView.scrollToPosition(positionStart);
            }
        }
    });
    recyclerView.setLayoutManager(mLinearlayoutManager);
    recyclerView.setAdapter(mAdapter);
}

ViewHolder Class

public static class InMessageViewHolder extends RecyclerView.ViewHolder{
    TextView inMessage;
    TextView receiver;
    CircleImageView receiverImage;

    public InMessageViewHolder(View itemView) {
        super(itemView);
        inMessage = (TextView) itemView.findViewById(R.id.textView11);
        receiver = (TextView) itemView.findViewById(R.id.textView12);
    }
}

Answer 1

您可以覆盖getItemViewType的{{1}}来实现此目的：

FirebaseRecyclerAdapter

这将导致// Check if the item at position is sender private boolean isSender(int position) { sender.equals(getItem(position).getSender()); } @Override public int getItemViewType(int position) { if (isSender(position)) { return R.layout.my_sender_layout; } else { return R.layout.my_receiver_layout; } }有条件地扩充布局。但是，您仍然只能拥有一个RecyclerAdapter子类，因此您需要确保在实现ViewHolder时，您的代码已准备好public MyViewHolder(View itemView)成为两个布局之一，如果这些布局有不同的内容然后一些itemView调用将返回null。

Answer 2

您阅读https://guides.codepath.com/android/Heterogenous-Layouts-inside-RecyclerView#prerequisite

此外，为了使用少量的FirebaseRecyclerAdapter代码，您可以扩展并提供仅供查看的功能。其他人会从Firebase Query等超级课程中得到关注。

请注意模型布局，当你覆盖onCreateViewHolder时，它可以是-1

如何在聊天应用程序中将FirebaseRecyclerAdapter用于两个项目布局

2 个答案: