android - Firebase ui - 在 android 中为 FirebaseRecyclerView 设置标题 View

Question

我需要在 RecyclerView 中添加标题 View ，我使用的适配器来自 Firebase ui。

对于普通的 RecyclerView 适配器，我会简单地处理不同的 View 类型并处理一些计数/位置偏移。

但是在 FirebaseAdapter 中采用相同的方法似乎是一种不好的做法，在这种情况下最好的方法是什么。

这是我能得到的最接近的。

       mAdapter = new FirebaseRecyclerAdapter<Comment, RecyclerView.ViewHolder>(Comment.class,
            R.layout.item_comment, CommentHolder.class, ref) {

        final static int TYPE_HEADER = 0;
        final static int TYPE_ITEM = 1;

        @Override
        protected void populateViewHolder(RecyclerView.ViewHolder viewHolder, Comment comment, int position) {
            //cast to comment holder
            final CommentHolder commentViewHolder = (CommentHolder) viewHolder;

            //initialize view
            commentViewHolder.setComment(comment.getComment());
            commentViewHolder.setTime(comment.getTimestamp());

            //get user details and set view
            DatabaseReference ref = FirebaseDatabase.getInstance().getReference(FireContract.PATH_USER_PROFILE)
                    .child(comment.getUserKey());
            ref.addListenerForSingleValueEvent(new ValueEventListener() {
                @Override
                public void onDataChange(DataSnapshot dataSnapshot) {
                    User user = dataSnapshot.getValue(User.class);
                    if(user != null) {
                        commentViewHolder.setName(user.getName());
                        commentViewHolder.setUsername("@" + user.getUsername());
                    }
                }

                @Override
                public void onCancelled(DatabaseError databaseError) {

                }
            });
        }

        //return header view holder is type is header else return super from firebase ui
        @Override
        public RecyclerView.ViewHolder onCreateViewHolder(ViewGroup parent, int viewType) {
            if(viewType == TYPE_HEADER){
                View view = LayoutInflater.from(getActivity()).inflate(R.layout.post_details,
                        parent, false);

                return new PostViewHolder(view);
            }
            else
                return super.onCreateViewHolder(parent, viewType);
        }

        //initialize post details as header if position is 0 else call super with position less
        //by one to cater for the header offset
        @Override
        public void onBindViewHolder(RecyclerView.ViewHolder viewHolder, int position) {
            if(position == 0)
                initializePostDetails((PostViewHolder) viewHolder);
            else
                super.onBindViewHolder(viewHolder, position - 1);
        }

        //return view type header if position is 0 else call super from firebase ui
        @Override
        public int getItemViewType(int position) {
            if(position == 0)
                return TYPE_HEADER;

            return super.getItemViewType(position - 1);
        }

        //set count equal to 1 plus actual list items, 1 is added for header view
        @Override
        public int getItemCount() {
            return super.getItemCount() + 1;
        }

    };

但这给出了一个 cannot resolve constructor 问题，但即使在解决这个问题之后它也可能无法工作。

Answer 1

因此，这就是我能够将我的适配器升级到的目标，它确实对我有用，但不确定它是否仍然是实现此目标的最佳方法。如果有人可以验证这一点或者可以提出更好更简单的解决方案，那就太好了

mAdapter = new FirebaseRecyclerAdapter<Comment, RecyclerView.ViewHolder>(Comment.class,
            R.layout.item_comment, RecyclerView.ViewHolder.class, ref) {

        final static int TYPE_HEADER = 0;
        final static int TYPE_ITEM = 1;

        @Override
        protected void populateViewHolder(RecyclerView.ViewHolder viewHolder, Comment comment, int position) {
            Log.d(TAG, "running populateViewHolder");
        }

        //return header view holder is type is header else return super from firebase ui
        @Override
        public RecyclerView.ViewHolder onCreateViewHolder(ViewGroup parent, int viewType) {
            if(viewType == TYPE_HEADER){
                View view = LayoutInflater.from(getActivity()).inflate(R.layout.post_details,
                        parent, false);

                return new PostViewHolder(view);
            }
            //if type is not header its item view, so return commentHolder instance
            else{
                View view = LayoutInflater.from(getActivity()).inflate(R.layout.item_comment,
                        parent, false);

                return new CommentHolder(view);
            }

        }

        //initialize post details as header if position is 0 else call super with position less
        //by one to cater for the header offset
        @Override
        public void onBindViewHolder(RecyclerView.ViewHolder viewHolder, int position) {
            //if holder is post view holder, initialize header
            if(viewHolder instanceof PostViewHolder)
                initializePostDetails((PostViewHolder) viewHolder);

            else{
                //cast to comment holder
                final CommentHolder commentViewHolder = (CommentHolder) viewHolder;
                Comment comment = getItem(position);

                //initialize view
                commentViewHolder.setComment(comment.getComment());
                commentViewHolder.setTime(comment.getTimestamp());

                //get user details and set view
                DatabaseReference ref = FirebaseDatabase.getInstance().getReference(FireContract.PATH_USER_PROFILE)
                        .child(comment.getUserKey());
                ref.addListenerForSingleValueEvent(new ValueEventListener() {
                    @Override
                    public void onDataChange(DataSnapshot dataSnapshot) {
                        User user = dataSnapshot.getValue(User.class);
                        if(user != null) {
                            commentViewHolder.setName(user.getName());
                            commentViewHolder.setUsername("@" + user.getUsername());
                        }
                    }

                    @Override
                    public void onCancelled(DatabaseError databaseError) {

                    }
                });
            }

        }

        //return view type header if position is 0 else call super from firebase ui
        @Override
        public int getItemViewType(int position) {
            if(position == 0)
                return TYPE_HEADER;

            return TYPE_ITEM;
        }

        //set count equal to 1 plus actual list items, 1 is added for header view
        @Override
        public int getItemCount() {
            return super.getItemCount() + 1;
        }

        //return comment item, decrement 1 from position to avoid out of rand exception as it was
        //incremented for adding header
        @Override
        public Comment getItem(int position) {
            return super.getItem(position - 1);
        }
    };