content: /*
   * Copyright 1999-2023 Alibaba Group Holding Ltd.
   *
   * 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.alibaba.nacos.client.naming.listener;
  
  import com.alibaba.nacos.api.naming.listener.AbstractEventListener;
  import com.alibaba.nacos.api.naming.listener.Event;
  
  /**
   * Listener for NamingChangeEvent.
   *
   * @author lideyou
   */
  public abstract class AbstractNamingChangeListener extends AbstractEventListener {
      
      @Override
      public final void onEvent(Event event) {
          if (event instanceof NamingChangeEvent) {
              onChange((NamingChangeEvent) event);
          }
      }
      
      /**
       * Callback when instances have changed.
       *
       * @param event NamingChangeEvent
       */
      public abstract void onChange(NamingChangeEvent event);
  }
  