如何从firebase节点获取值

Question

我想在Android Studio中获取isSeen节点的值。M6F2mJjQ8uGPXAynZzV是消息的id，并将消息更改为消息。我想在适配器类中获得这个值。

Answer 1

如果要获取isSeen值，请尝试以下操作：

DatabaseReference ref = FirebaseDatabase.getInstance().getReference().child("Chats");
ref.addListenerForSingleValueEvent(new ValueEventListener() {
         @Override
      public void onDataChange(DataSnapshot dataSnapshot) {
           for(DataSnapshot data: dataSnapshot.getChildren()){
                   Boolean isSeen = data.child("isSeen").getValue(Boolean.class);
                  }
            }

        @Override
       public void onCancelled(DatabaseError databaseError) {
                  throw databaseError.toException();
               }
          });

在Chats节点内迭代，然后可以检索isSeen。

Answer 2

所以你想得到一个布尔值，转换为字符串，并将其与另一个字符串进行比较：

如果这是你想要的，那么这就是你的答案：

//this is the string that you want to compare against
String yourString = "true";

//this is your reference
DatabaseReference ref = FirebaseDatabase.getInstance().getReference().child("Chats");


//make a listener
ValueEventListener listener = new ValueEventListener() {
    @Override
    public void onDataChange(DataSnapshot dataSnapshot) {
        //loop through the random key IDs

        for(DataSnapshot ds : dataSnapshot.getChildren()){
        //get the boolean "isSeen"
        boolean isSeen = ds.child("isSeen").getValue(Boolean.class);

        //convert boolean to string
        String isSeenString = String.valueOf(isSeen);

        //compare isSeenString with your String

        if(isSeenString.equals(yourString)){
          //they are equal

         }else{
          //they are not equal

           }

        }
    }

    @Override
    public void onCancelled(DatabaseError databaseError) {

    }
};

//add the listener
ref.addValueEventListener(listener);