如何添加点赞计数器 Android Studio Firebase

Question

this is the database link 1任何人都可以帮我添加一个喜欢的计数器。请 它应该显示点赞数，并在点赞被收回时将其关闭 我的java代码在下面

 private void onLikeClicked(View v) {
    boolean isLiked = !btnLike.isSelected();
    final String currentUserKey = User.currentKey();

    DatabaseReference likes = FirebaseDatabase.getInstance().getReference().child(Const.kDataLikeKey);
    DatabaseReference curLike = likes.child(mPostRef.getKey()).child(currentUserKey).child("liked");

    // update Model
    curLike.setValue(isLiked);

    // update UI
    btnLike.setSelected(isLiked);
}

这个增量类似于 count 但不会减少它我希望它在点击返回时减少

Answer 1

您的问题并不完全清楚，但如果您尝试制作社交媒体帖子之类的功能，用户可以喜欢而不是帖子，这会有所帮助。

数据结构

Post-> postId -> likes -> 1 
              ...

你可以分为三部分：

1. 显示帖子的点赞数，postId 和当前用户 userId1，是否点赞了您的帖子

   public void displayNumberOfLikes(String postId, String currentUserId){
       DatabaseReference likesRef = FirebaseDatabase.getInstance().getReference().child('Post').child(postId);
       likesRef.addValueEventListener(new ValueEventListener(){
           @Override
           public void onDataChange(DataSnapshot dataSnapshot) {
               if(dataSnapshot.exists()){
                   long numOfLikes = 0;
                   if(dataSnapshot.hasChild("likes")){
                       numOfLikes = dataSnapshot.child("likes").getValue(Long.class);
                   }
   
                   //Populate numOfLikes on post i.e. textView.setText(""+numOfLikes)
                   //This is to check if the user has liked the post or not
                   btnLike.setSelected(dataSnapshot.hasChild(userId));
               }
           }
   
           @Override
           public void onCancelled(DatabaseError databaseError) {
   
           }
       });
   }
   

2. 点赞

   public void onLikeClicked(View v, String postId, String userId){
       DatabaseReference likesRef = FirebaseDatabase.getInstance().getReference().child('Post').child(postId).child("likes");
       likesRef.addListenerForSingleValueEvent(new ValueEventListener(){
           @Override
           public void onDataChange(DataSnapshot dataSnapshot) {
               long numLikes = 0;
               if(dataSnapshot.exists()){
                   numLikes = dataSnapshot.getValue(Long.class);
               }
               boolean isLiked = btnLike.isSelected();
               if(isLiked){
                  //If already liked then user wants to unlike the post
                  likesRef.set(numLikes-1);
               }else {
                  //If not liked already then user wants to like the post
                  likesRef.set(numLikes+1);
               }
           }
   
           @Override
           public void onCancelled(DatabaseError databaseError) {
   
           }
       });
   }
   

通过这种方式，您可以让您的用户喜欢和不喜欢帖子并显示喜欢的总数。 希望对您有所帮助！