001/* 002 * Licensed to the Apache Software Foundation (ASF) under one 003 * or more contributor license agreements. See the NOTICE file 004 * distributed with this work for additional information 005 * regarding copyright ownership. The ASF licenses this file 006 * to you under the Apache License, Version 2.0 (the 007 * "License"); you may not use this file except in compliance 008 * with the License. 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, 013 * software distributed under the License is distributed on an 014 * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY 015 * KIND, either express or implied. See the License for the 016 * specific language governing permissions and limitations 017 * under the License. 018 * 019 */ 020package org.apache.directory.api.ldap.model.schema.comparators; 021 022 023import org.apache.directory.api.i18n.I18n; 024import org.apache.directory.api.ldap.model.schema.LdapComparator; 025import org.slf4j.Logger; 026import org.slf4j.LoggerFactory; 027 028 029/** 030 * Compares two objects taking into account that one might be a Comparable. 031 * 032 * @author <a href="mailto:dev@directory.apache.org">Apache Directory Project</a> 033 * @param <T> the type, must extend {@link Comparable} 034 */ 035public class ComparableComparator<T> extends LdapComparator<Comparable<T>> 036{ 037 /** The serial version UID */ 038 private static final long serialVersionUID = 2L; 039 040 /** A logger for this class */ 041 private static final Logger LOG = LoggerFactory.getLogger( ComparableComparator.class ); 042 043 044 /** 045 * The ComparableComparator constructor. 046 * 047 * @param oid the comparator OID 048 */ 049 public ComparableComparator( String oid ) 050 { 051 super( oid ); 052 } 053 054 055 /** 056 * Compares two objects taking into account that one may be a Comparable. If 057 * the first is a comparable then its compareTo operation is called and the 058 * result returned as is. If the first is not a Comparable but the second is 059 * then its compareTo method is called and the result is returned after 060 * being negated. If none are comparable the hashCode of o1 minus the 061 * hashCode of o2 is returned. 062 * 063 * @param o1 the first comparable 064 * @param o2 the second comparable 065 * @return {@inheritDoc} 066 */ 067 @SuppressWarnings("unchecked") 068 public int compare( Comparable<T> o1, Comparable<T> o2 ) 069 { 070 if ( LOG.isDebugEnabled() ) 071 { 072 LOG.debug( I18n.msg( I18n.MSG_13755_COMPARING_OBJECTS, o1, o2 ) ); 073 } 074 075 if ( o1 == null ) 076 { 077 if ( o2 == null ) 078 { 079 return 0; 080 } 081 else 082 { 083 return -1; 084 } 085 } 086 087 if ( o2 == null ) 088 { 089 return 1; 090 } 091 092 return o1.compareTo( ( T ) o2 ); 093 } 094}