Android Firebase自定义RecyclerView项目单击问题

Question

I have to use custom RecyclerView because I don't want to update to list real time.

How do I get an id if I want to go into the details of the data? As in FirebaseRecyclerAdapter.

  final String uid = getRef(position).getKey();

I added postId , my posts table, and I wrote the following code. But when click on the image, it goes to the last added image to the list. And when I click upVote, every item goes crazy and they click upVote too.

First, am I on the right track to update the list only when I want to? Second, why is everything going crazy?

PostAdapter

public PostRecyclerAdapter(Context context, Query query) {
    this.context = context;
    this.query = query;

    query.addValueEventListener(new ValueEventListener() {
        @Override
        public void onDataChange(DataSnapshot dataSnapshot) {
            posts.clear();
            for (DataSnapshot data : dataSnapshot.getChildren()) {
                posts.add(data.getValue(Post.class));
            }
            Collections.sort(posts, new Comparator<Post>() {
                @Override
                public int compare(Post o1, Post o2) {
                    Long a = o1.getCreatedDate();
                    Long b = o2.getCreatedDate();
                    if (a < b) {
                        return -1;
                    } else if (a == b) {
                        return 0;
                    } else {
                        return 1;
                    }
                }
            });
            notifyDataSetChanged();
        }

        @Override
        public void onCancelled(DatabaseError databaseError) {

        }
    });
}

 @Override
public void onBindViewHolder(final PostViewHolder viewHolder, int position) {

    model = posts.get(position);
    postId = model.getPostId();
    viewHolder.setTitle(model.getTitle());
    viewHolder.setImage(context, model.getImage());
    viewHolder.setUpVote(postId);

     viewHolder.imvImage.setOnClickListener(new View.OnClickListener() {
        @Override
        public void onClick(View view) {
            Intent intent = new Intent(context, SinglePostActivity.class);
            intent.putExtra(Enums.PostKeys.postId.getValue(), postId);
            context.startActivity(intent);
        }
    });

 viewHolder.imbUpVote.setOnClickListener(new View.OnClickListener() {
        @Override
        public void onClick(View view) {

            if (!checkAuthUser()) {
                context.startActivity(new Intent(context, SignUpActivity.class));
                return;
            }
            processVote = true;

            Singleton.getDbPostDownVote(postId).child(postId).addValueEventListener(new ValueEventListener() {
                @Override
                public void onDataChange(DataSnapshot dataSnapshot) {
                    if (processVote == true) {
                        if (dataSnapshot.hasChild(getUserId())) {
                            Singleton.getDbPostDownVote(postId).child(postId).child(getUserId()).removeValue();
                        }
                    }
                }

                @Override
                public void onCancelled(DatabaseError databaseError) {

                }
            });

            Singleton.getDbPostUpVote(postId).child(postId).addValueEventListener(new ValueEventListener() {
                @Override
                public void onDataChange(DataSnapshot dataSnapshot) {


                    if (processVote == true) {
                        if (dataSnapshot.hasChild(getUserId())) {
                            Singleton.getDbPostUpVote(postId).child(postId).child(getUserId()).removeValue();
                            processVote = false;
                        } else {
                            Singleton.getDbPostUpVote(postId).child(postId).child(getUserId()).setValue(0);
                            processVote = false;
                        }
                    }
                }

                @Override
                public void onCancelled(DatabaseError databaseError) {

                }
            });

        }
    });

}

PostViewHolder:setUpVote

public void setUpVote(final String postId) {
    Singleton.getDbPostUpVote(postId).child(postId).addValueEventListener(new ValueEventListener() {
        @Override
        public void onDataChange(DataSnapshot dataSnapshot) {
            if (dataSnapshot.hasChild(getUid())) {
                imbUpVote.setImageResource(R.drawable.vote_up_active);
            } else {
                imbUpVote.setImageResource(R.drawable.vote_up_passive);
            }
        }

        @Override
        public void onCancelled(DatabaseError databaseError) {

        }
    });
}

Answer 1

How do I get an id if I want to go into the details of the data?

Usually the id is a node in your db. As you can see in

final String uid = getRef(position).getKey();

getKey returns tha value of the node in db. In your case to avoid sorting the list with comparator i would just structure the data like so:

20170111
  title : some title
  text : some text
20170112
  title : some title
  text : some text

This way data is going to be sorted by the nodes, which is the date, by Firebase. If you want to be more precise you can also add hours and minutes.

First, am I on the right track to update the list only when I want to?

No.

Calling addValueEventListener() is going to trigger the code inside the listener each time the value in your db changes. In other words, its realtime. Use addListenerForSingleValueEvent() insted. It fires only once.

Second, why is everything going crazy?

Very important thing about onDataChange() is that it fires not only when the value changes but also the first time you set the listener. That is why everything is getting voted up when you click one item.