我想从firebase数据库中读取特定数据.我目前正在做的是这里.

DatabaseReference database = FirebaseDatabase.getInstance().getReference();

DatabaseReference myRef = database.child("profiles/");

myRef.child(phoneNo).addListenerForSingleValueEvent(new ValueEventListener() {

@Override

public void onDataChange(DataSnapshot dataSnapshot) {

user = dataSnapshot.getValue(User.class);

}

@Override

public void onCancelled(DatabaseError databaseError) {}

});

写入DB的方法

public void writeToDBProfiles(Object data,String phoneNo) {

DatabaseReference database = FirebaseDatabase.getInstance().getReference();

DatabaseReference myRef = database.child("profiles/" + phoneNo);

myRef.setValue(data);

}

但它返回null …任何帮助将不胜感激.