如何添加像计数器Android Studio Firebase

Question

这是数据库链接1任何人都可以帮我添加一个喜欢计数器吗？ 它应该显示 no：of 喜欢，并在收回喜欢时将其删除 我的 Java 代码如下

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);
}

这个增量像计数，但不递减它，我希望它在点击回来时减少

Answer 1

您的问题并不完全清楚，但是如果您正在尝试制作像社交媒体帖子这样的功能，用户可以喜欢并且与帖子不同，这可以提供帮助。

数据结构

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

您可以将其分为三个部分：

1. 要显示帖子的喜欢数，postId和当前用户userId1是否喜欢您的帖子

   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. 打开喜欢点击

   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！