001    /*--------------------------------------------------------------------------+
002    $Id: IdentifierBasedComparatorBase.java 26283 2010-02-18 11:18:57Z juergens $
003    |                                                                          |
004    | Copyright 2005-2010 Technische Universitaet Muenchen                     |
005    |                                                                          |
006    | Licensed under the Apache License, Version 2.0 (the "License");          |
007    | you may not use this file except in compliance with the License.         |
008    | You may obtain a copy of the License at                                  |
009    |                                                                          |
010    |    http://www.apache.org/licenses/LICENSE-2.0                            |
011    |                                                                          |
012    | Unless required by applicable law or agreed to in writing, software      |
013    | distributed under the License is distributed on an "AS IS" BASIS,        |
014    | WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. |
015    | See the License for the specific language governing permissions and      |
016    | limitations under the License.                                           |
017    +--------------------------------------------------------------------------*/
018    package edu.tum.cs.commons.collections;
019    
020    import java.util.Comparator;
021    
022    /**
023     * Base class for comparators that compare to objects by comparing a suitable
024     * object identifier.
025     * 
026     * @author deissenb
027     * @author $Author: juergens $
028     * @version $Rev: 26283 $
029     * @levd.rating GREEN Hash: FFF69AADA13F4571BB8935BD37068935
030     */
031    public abstract class IdentifierBasedComparatorBase<I extends Comparable<I>, T>
032                    implements Comparator<T> {
033    
034            /** Compare by identifier. */
035            public int compare(T object1, T object2) {
036                    return obtainIdentifier(object1).compareTo(obtainIdentifier(object2));
037            }
038    
039            /** Get identifier for object. */
040            abstract protected I obtainIdentifier(T object);
041    }