如何知道Firebase ChildEventListener是否找到子级？[android]

相关事件发生 时

ChildEventListener

onChildAdded()

ChildEventListener

检测孩子是否存在的最简单方法是使用

ValueEventListener

public void searchemail(String email){  Firebase ref = new Firebase("https://<myfirebase>.firebaseio.com/users");  Query queryRef = ref.orderByChild("Email").equalTo(email);   ValueEventListener listener = new ValueEventListener() {     @Override     public void onDataChanged(DataSnapshot snapshot) {       if (snapshot.exists()) {         for (DataSnapshot child: snapshot.getChildren()) {homeintent.putExtra("key", child.getKey());startActivity(homeintent);break; // exit for loop, we only want one match         }       }       else {         Toast toast = Toast.makeText(this, "email not found", Toast.LENGTH_SHORT);       }     }   };   queryRef.addValueEventListener(listener);}