/**

  * Copyright 2005-2011 The Kuali Foundation

  *

  * Licensed under the Educational Community 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.opensource.org/licenses/ecl2.php

  *

  * 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.kuali.rice.core.api.cache;

 import java.util.ArrayList;

 import java.util.Collection;

 import java.util.Collections;

 import java.util.List;

 import java.util.Map;

 import java.util.SortedMap;

 import java.util.TreeMap;

 /**

  * This is a utility class that generates cache keys for compound objects.

  */

 public final class CacheKeyUtils {

     private CacheKeyUtils() {

         throw new UnsupportedOperationException("do not call.");

     }

     /**

      * Create a String key value out of a Map.  The Map should really just contain

      * simple types.

      * @param map the map.  if null will return ""

      * @param <K> the map key type

      * @return the map as a string value

      */

     public static <K extends Comparable<K>> String key(Map<K, ?> map) {

         if (map == null) {

             return "";

         }

         final SortedMap<K, ?> sorted = new TreeMap<K, Object>(map);

         final StringBuilder b = new StringBuilder("[");

         for (Map.Entry<K, ?> entry : sorted.entrySet()) {

             if (entry != null && entry.getKey() != null && entry.getValue() != null) {

                 b.append(entry.getKey());

                 b.append(":");

                 b.append(entry.getValue());

                 b.append(",");

             }

         }

         b.append("]");

         return b.toString();

     }

     /**

      * Create a String key value out of a Collection.  The Collection should really just contain

      * simple types.

      * @param col the collection.  if null will return ""

      * @param <K> the col type

      * @return the collection as a string value

      */

     public static <K extends Comparable<K>> String key(Collection<K> col) {

         if (col == null) {

             return "";

         }

         final List<K> sorted = new ArrayList<K>(col);

         Collections.sort(sorted);

         final StringBuilder b = new StringBuilder("[");

         for (K entry : sorted) {

             if (entry != null) {

                 b.append(entry);

                 b.append(",");

             }

         }

         b.append("]");

         return b.toString();

     }

 }