我怎样才能得到每个孩子？ Firebase getValue [android]

Question

我怎么能从我的数据库中获取所有孩子？

此代码获得第一个元素，我如何获得Element_2,3并且接连？我最好的帮助是序列化第一个国家并打印它。

我的数据库：

 { 
    "Capitals" : { 
    "Country_1" : { 
    "Country" : "Macedonia", 
    "Capital" : "Skopje" 
    }, 
    "Country_2" : { 
    "Country" : "Madagascar", 
    "Capital" : "Antananarivo"  
    }, 
    "Country_3" : { 
    "Country" : "Malawi", 
    "Capital" : "Lilongwe" 
    } 
    } 

我的代码

@Override 
public void onStart(){ 
    super.onStart(); 
    final FirebaseDatabase database = FirebaseDatabase.getInstance(); 
    DatabaseReference capitalsRef = database.getReference("Capitals"); 
    compresoresRef.orderByChild("Ref").addChildEventListener(new ChildEventListener() { 
    @Override 
    public void onChildAdded(DataSnapshot dataSnapshot, String s) { 
     countryModel cm = dataSnapshot.getValue(countryModel.class); 
     String country = cm.getCountry(); 
     String capital= cm.getCapital(); 
     textData1.setText(country); 
     textData2.setText(capital); 
    } 

    @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) { 
    } 
     }); 

的dataSnapshot在执行的模样：

DataSnapshot { key =Country_1, value = {Country=Macedonia, Capital=Skopje} } 

Answer 1

你应该使用addChildEventListener

ArrayList<countryModel> countryList = new ArrayList<countryModel)(); 
compresoresRef.orderByChild("Ref").addChildEventListener(new ChildEventListener() { 
    @Override 
    public void onChildAdded(DataSnapshot dataSnapshot, String s) { 
     countryModel cm = dataSnapshot.getValue(countryModel.class); 
     countryList.add(cm); 
     ... 
    } 
} 

或者你用addValueEventListener用于检索数据，如果使用ArrayList店面，你从火力地堡获得所有孩子的，它看起来像

compresoresRef.addValueEventListener(new ValueEventListener() { 
    public void onDataChange(DataSnapshot snapshot) { 
     countryList.clear(); 
     for (DataSnapshot postSnapshot: snapshot.getChildren()) { 
      countryModel cm = postSnapshot.getValue(countryModel.class); 
      countryList.add(cm); 
     } 
    } 

    public void onCancelled(FirebaseError firebaseError) { 
     System.out.println("The read failed: " + firebaseError.getMessage()); 
    } 
}); 

Answer 2

试试这个

@Override 
    public void onChildAdded(DataSnapshot dataSnapshot, String s) { 
     for(DataSnapshot post:dataSnapshot.getChildren()) 
     { 
     countryModel countryModel cm = post.getValue(countryModel.class); 
     } 
    }