Question

我正在尝试制作简单的“与众不同”系统，但是当我按“喜欢”按钮时，它只会上升，我无法与众不同，例如，如果我有5个“喜欢”而我的价值保持不变，则计数器不会下降5.我是Firebase Android编程的新手，我不知道如何正确实现这一点，希望有人可以帮助我。

这是我的代码，如果这不是正确的代码，则可以发布整个代码。

private void setUpVote(final ViewHolder holder) {
        final DatabaseReference reference = FirebaseDatabase.getInstance().getReference();
        final String userId = holder.post.getUser_id();
        final String postId = holder.post.getPost_id();
        holder.mUpVote.setOnLikeListener(new OnLikeListener() {
            @Override
            public void liked(LikeButton likeButton) {
                reference.child("up_votes").child(holder.currentUserID).child(holder.post.getPost_id()).setValue("true");
                reference.child("posts").child(holder.post.getPost_id()).child("up_votes").child(holder.currentUserID).setValue("true");
                getUpVote(holder);
                holder.mDownVote.setEnabled(false);
                setUserPoints(userId, holder);
                setPostPoints(postId, holder);
            }

            @Override
            public void unLiked(LikeButton likeButton) {

            }
        });
    }

    private void getUpVote(final ViewHolder holder) {
        String postID = holder.post.getPost_id();
        final DatabaseReference reference = FirebaseDatabase.getInstance().getReference();
        DatabaseReference newReference = reference.child("posts").child(postID).child("up_votes");
        newReference.addValueEventListener(new ValueEventListener() {
            @Override
            public void onDataChange(DataSnapshot dataSnapshot) {
                // This method is called once with the initial value and again
                // whenever data at this location is updated.
                if (dataSnapshot.hasChild(holder.currentUserID)) {
                    holder.upVotedByCurrentUser = true;
                    setState(holder);
                } else {
                    holder.upVotedByCurrentUser = false;
                }
                long numUpVotes = dataSnapshot.getChildrenCount();

                holder.mCountUpVote.setText(String.valueOf(numUpVotes));
            }


            @Override
            public void onCancelled(DatabaseError error) {
                // Failed to read value
                Log.w(TAG, "Failed to read value.", error.toException());
            }
        });
    }

    private void setDownVote(final ViewHolder holder) {
        final DatabaseReference reference = FirebaseDatabase.getInstance().getReference();
        final String postId = holder.post.getPost_id();
        holder.mDownVote.setOnLikeListener(new OnLikeListener() {
            @Override
            public void liked(LikeButton likeButton) {
                reference.child("down_votes").child(holder.currentUserID).child(holder.post.getPost_id()).setValue("true");
                reference.child("posts").child(holder.post.getPost_id()).child("down_votes").child(holder.currentUserID).setValue("true");
                getDownVote(holder);
                holder.mUpVote.setEnabled(false);
                setPostPoints(postId, holder);
            }

            @Override
            public void unLiked(LikeButton likeButton) {
            }
        });
    }

    private void getDownVote(final ViewHolder holder) {
        String postID = holder.post.getPost_id();
        final DatabaseReference reference = FirebaseDatabase.getInstance().getReference();
        DatabaseReference newReference = reference.child("posts").child(postID).child("down_votes");
        newReference.addValueEventListener(new ValueEventListener() {
            @Override
            public void onDataChange(DataSnapshot dataSnapshot) {
                // This method is called once with the initial value and again
                // whenever data at this location is updated.
                if (dataSnapshot.hasChild(holder.currentUserID)) {
                    holder.downVotedByCurrentUser = true;
                    setState(holder);
                } else {
                    holder.downVotedByCurrentUser = false;
                }
                long numDownVotes = dataSnapshot.getChildrenCount();

                holder.mCountDownVote.setText(String.valueOf(numDownVotes));
            }

我希望有人能帮助我！

Answer 1

这不是解决此类问题的最佳方法。当涉及到喜欢和不同时，出现的第一个问题与并发修改有关，在这种情况下，您应该使用事务来在数据库中获得准确的数据。

因此，在这种情况下，我建议您使用 post 中的答案，但应该使用喜欢代替得分。同样的原则也适用。

像和不像Firebase无法正常工作的系统

1 个答案: