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/* 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 org.camunda.bpm.engine.impl.util;

import java.util.ArrayList;
import java.util.Collection;
import java.util.Collections;
import java.util.HashMap;
import java.util.HashSet;
import java.util.List;
import java.util.Map;
import java.util.Set;

/**
 * helper/convience methods for working with collections.
 *
 * @author Joram Barrez
 */
public class CollectionUtil {

  // No need to instantiate
  private CollectionUtil() {}

  /**
   * Helper method that creates a singleton map.
   *
   * Alternative for Collections.singletonMap(), since that method returns a
   * generic typed map  depending on the input type, but we often need a
   *  map.
   */
  public static Map singletonMap(String key, Object value) {
    Map map = new HashMap();
    map.put(key, value);
    return map;
  }

  /**
   * Arrays.asList cannot be reliably used for SQL parameters on MyBatis < 3.3.0
   */
  public static  List asArrayList(T[] values) {
    ArrayList result = new ArrayList();
    Collections.addAll(result, values);

    return result;
  }

  public static  void addToMapOfLists(Map> map, S key, T value) {
    List list = map.get(key);
    if (list == null) {
      list = new ArrayList();
      map.put(key, list);
    }
    list.add(value);
  }

  public static  void addToMapOfSets(Map> map, S key, T value) {
    Set set = map.get(key);
    if (set == null) {
      set = new HashSet();
      map.put(key, set);
    }
    set.add(value);
  }

  public static  void addCollectionToMapOfSets(Map> map, S key, Collection values) {
    Set set = map.get(key);
    if (set == null) {
      set = new HashSet();
      map.put(key, set);
    }
    set.addAll(values);
  }
}