从Firebase中检索数据 [英] retrive data from firebase

问题描述

我是android开发新手。我试图从firebase中检索数据。哪些工作。但我无法过滤数据库结果的唯一标识符。

  FirebaseDatabase database = FirebaseDatabase.getInstance（）; 
 DatabaseReference myref = database.getReference（user_foods）; 
 myref.addListenerForSingleValueEvent（new ValueEventListener（）{
 @Override $ b $ public void onDataChange（DataSnapshot dataSnapshot）{
 Log.d（foods，dataSnapshot.getValue（）。toString （））; 
} 
 
 @Override 
 public void onCancelled（DatabaseError databaseError）{
 $ b} 
}）; 
  

结果就像

XsgGhY7qUY5Qa3t8 = {food = apple}，.....等等

我想删除唯一标识符&只显示结果为

Apple，Mango ...等

谢谢

解决方案

我想出了答案。如果任何人有相同的问题使用子事件侦听器

pre $ firebaseDatabase database = FirebaseDatabase.getInstance（）;
DatabaseReference myref = database.getReference（user_foods）;
myref.addChildEventListener（new ChildEventListener（）{
@Override
public void onChildAdded（DataSnapshot dataSnapshot，String s）{
Log.d（foods，dataSnapshot.getValue ）.toString（））;

}
$ b $ @覆盖
public void onChildChanged（DataSnapshot dataSnapshot，String s）{

}

@Override
public void onChildRemoved（DataSnapshot dataSnapshot）{


$ b @Override
public void onChildMoved（DataSnapshot dataSnapshot，String s）{

}

@Override
public void onCancelled（DatabaseError databaseError）{

}
}）;

I'm new to android developing. I tried retrieving data from firebase. which worked . but I'm unable to filter unique identifier from database results .

   FirebaseDatabase database = FirebaseDatabase.getInstance();
        DatabaseReference myref = database.getReference("user_foods");
        myref.addListenerForSingleValueEvent(new ValueEventListener() {
            @Override
            public void onDataChange(DataSnapshot dataSnapshot) {
                Log.d("foods",dataSnapshot.getValue().toString());
            }

            @Override
            public void onCancelled(DatabaseError databaseError) {

            }
        });

results are like

XsgGhY7qUY5Qa3t8 = {food = apple} , ..... etc

I want to remove that unique identifier & just display results as

Apple , Mango ...etc

thank you

解决方案

I figured the answer. If anyone has same issue use "child event listener "

 FirebaseDatabase database = FirebaseDatabase.getInstance();
    DatabaseReference myref = database.getReference("user_foods");
    myref.addChildEventListener(new ChildEventListener() {
        @Override
        public void onChildAdded(DataSnapshot dataSnapshot, String s) {
            Log.d("foods",dataSnapshot.getValue().toString());

        }

        @Override
        public void onChildChanged(DataSnapshot dataSnapshot, String s) {

        }

        @Override
        public void onChildRemoved(DataSnapshot dataSnapshot) {

        }

        @Override
        public void onChildMoved(DataSnapshot dataSnapshot, String s) {

        }

        @Override
        public void onCancelled(DatabaseError databaseError) {

        }
    });

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