content: /*
   * Copyright 1999-2012 Alibaba Group.
   *  
   * 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.
   */
  /**
   * (created at 2011-10-24)
   */
  package com.alibaba.cobar.util;
  
  import java.util.Collections;
  import java.util.HashSet;
  import java.util.Set;
  
  /**
   * @author <a href="mailto:shuo.qius@alibaba-inc.com">QIU Shuo</a>
   */
  public class CollectionUtil {
      /**
       * @param orig if null, return intersect
       */
      public static Set<? extends Object> intersectSet(Set<? extends Object> orig, Set<? extends Object> intersect) {
          if (orig == null)
              return intersect;
          if (intersect == null || orig.isEmpty())
              return Collections.emptySet();
          Set<Object> set = new HashSet<Object>(orig.size());
          for (Object p : orig) {
              if (intersect.contains(p))
                  set.add(p);
          }
          return set;
      }
  }
  