001    /*
002      Copyright (C) 2001-2004 Laurent Martelli <laurent@aopsys.com>
003    
004      This program is free software; you can redistribute it and/or modify
005      it under the terms of the GNU Lesser General Public License as
006      published by the Free Software Foundation; either version 2 of the
007      License, or (at your option) any later version.
008    
009      This program is distributed in the hope that it will be useful,
010      but WITHOUT ANY WARRANTY; without even the implied warranty of
011      MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
012      GNU Lesser General Public License for more details.
013    
014      You should have received a copy of the GNU Lesser General Public License
015      along with this program; if not, write to the Free Software
016      Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA */
017    
018    package org.objectweb.jac.aspects.persistence;
019    
020    import org.apache.log4j.Logger;
021    
022    
023    
024    /**
025     * Abstract class that defines an object identifier. It should be
026     * subclassed by <code>Storage</code> implementors.
027     *
028     * <strong>Note that you should also define the <code>hashCode</code>
029     * method.</em> 
030     */
031    public abstract class OID implements java.io.Serializable {
032    
033        static final Logger logger = Logger.getLogger("persistence");
034    
035        /**
036         * Test if two OIDs are equal.
037         * @param obj the OID to test
038         * @return true if obj equals this OID
039         */
040        public abstract boolean equals(Object obj);
041        public abstract int hashCode();
042        
043        public OID(Storage storage) {
044            this.storage = storage;
045            if (storage==null)
046                logger.error("Storage is null",new Exception());
047        }
048    
049        /** The storage that defines the OID */
050        protected Storage storage;
051        public final Storage getStorage() {
052            return storage;
053        }
054    
055        public abstract String localId();
056    }