content: /*
   *  Copyright (C) 2017-present Albie Liang. All rights reserved.
   *
   *  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 cc.suitalk.ipcinvoker.tools;
  
  import java.util.concurrent.ConcurrentHashMap;
  
  /**
   * Created by albieliang on 2020/6/4.
   *
   * @param <K>
   * @param <V>
   */
  public class SafeConcurrentHashMap<K, V> extends ConcurrentHashMap<K, V> {
  
      @Override
      public V get(Object key) {
          return key == null ? null : super.get(key);
      }
  
      @Override
      public V put(K key, V value) {
          if (key == null) {
              return null;
          }
          if (value == null) {
              return super.remove(key);
          }
          return super.put(key, value);
      }
  
      @Override
      public V remove(Object key) {
          return key == null ? null : super.remove(key);
      }
  
      @Override
      public boolean containsValue(Object value) {
          return value == null ? false : super.containsValue(value);
      }
  }