com.google.firebase.database.ValueEventListener Maven / Gradle / Ivy
/*
* Copyright 2017 Google Inc.
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package com.google.firebase.database;
/**
* Classes implementing this interface can be used to receive events about data changes at a
* location. Attach the listener to a location user {@link
* DatabaseReference#addValueEventListener(ValueEventListener)}.
*/
public interface ValueEventListener {
/**
* This method will be called with a snapshot of the data at this location. It will also be called
* each time that data changes.
*
* @param snapshot The current data at the location
*/
void onDataChange(DataSnapshot snapshot);
/**
* This method will be triggered in the event that this listener either failed at the server, or
* is removed as a result of the security and Firebase Database rules. For more information on
* securing your data, see:
*
* Security Quickstart
*
* @param error A description of the error that occurred
*/
void onCancelled(DatabaseError error);
}