001    /*
002     *  Licensed to the Apache Software Foundation (ASF) under one or more
003     *  contributor license agreements.  See the NOTICE file distributed with
004     *  this work for additional information regarding copyright ownership.
005     *  The ASF licenses this file to You under the Apache License, Version 2.0
006     *  (the "License"); you may not use this file except in compliance with
007     *  the License.  You may obtain a copy of the License at
008     *
009     *      http://www.apache.org/licenses/LICENSE-2.0
010     *
011     *  Unless required by applicable law or agreed to in writing, software
012     *  distributed under the License is distributed on an "AS IS" BASIS,
013     *  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
014     *  See the License for the specific language governing permissions and
015     *  limitations under the License.
016     */
017    package org.apache.commons.collections;
018    
019    import java.util.Map;
020    
021    /**
022     * A default implementation of {@link java.util.Map.Entry}
023     *
024     * @deprecated Use the version in the keyvalue subpackage. Will be removed in v4.0
025     * @since Commons Collections 1.0
026     * @version $Revision: 646777 $ $Date: 2008-04-10 13:33:15 +0100 (Thu, 10 Apr 2008) $
027     * 
028     * @author James Strachan
029     * @author Michael A. Smith
030     * @author Neil O'Toole
031     * @author Stephen Colebourne
032     */
033    public class DefaultMapEntry implements Map.Entry, KeyValue {
034        
035        /** The key */
036        private Object key;
037        /** The value */
038        private Object value;
039        
040        /**
041         * Constructs a new <code>DefaultMapEntry</code> with a null key
042         * and null value.
043         */
044        public DefaultMapEntry() {
045            super();
046        }
047    
048        /**
049         * Constructs a new <code>DefaultMapEntry</code> with the given
050         * key and given value.
051         *
052         * @param entry  the entry to copy, must not be null
053         * @throws NullPointerException if the entry is null
054         */
055        public DefaultMapEntry(Map.Entry entry) {
056            super();
057            this.key = entry.getKey();
058            this.value = entry.getValue();
059        }
060    
061        /**
062         * Constructs a new <code>DefaultMapEntry</code> with the given
063         * key and given value.
064         *
065         * @param key  the key for the entry, may be null
066         * @param value  the value for the entry, may be null
067         */
068        public DefaultMapEntry(Object key, Object value) {
069            super();
070            this.key = key;
071            this.value = value;
072        }
073    
074        // Map.Entry interface
075        //-------------------------------------------------------------------------
076        /**
077         * Gets the key from the Map Entry.
078         *
079         * @return the key 
080         */
081        public Object getKey() {
082            return key;
083        }
084    
085        /**
086         * Sets the key stored in this Map Entry.
087         * <p>
088         * This Map Entry is not connected to a Map, so only the local data is changed.
089         *
090         * @param key  the new key
091         */
092        public void setKey(Object key) {
093            this.key = key;
094        }
095        
096        /**
097         * Gets the value from the Map Entry.
098         *
099         * @return the value
100         */
101        public Object getValue() {
102            return value;
103        }
104    
105        /** 
106         * Sets the value stored in this Map Entry.
107         * <p>
108         * This Map Entry is not connected to a Map, so only the local data is changed.
109         *
110         * @param value  the new value
111         * @return the previous value
112         */
113        public Object setValue(Object value) {
114            Object answer = this.value;
115            this.value = value;
116            return answer;
117        }
118    
119        // Basics
120        //-----------------------------------------------------------------------
121        /**
122         * Compares this Map Entry with another Map Entry.
123         * <p>
124         * Implemented per API documentation of {@link java.util.Map.Entry#equals(Object)}
125         * 
126         * @param obj  the object to compare to
127         * @return true if equal key and value
128         */
129        public boolean equals(Object obj) {
130            if (obj == this) {
131                return true;
132            }
133            if (obj instanceof Map.Entry == false) {
134                return false;
135            }
136            Map.Entry other = (Map.Entry) obj;
137            return
138                (getKey() == null ? other.getKey() == null : getKey().equals(other.getKey())) &&
139                (getValue() == null ? other.getValue() == null : getValue().equals(other.getValue()));
140        }
141         
142        /**
143         * Gets a hashCode compatible with the equals method.
144         * <p>
145         * Implemented per API documentation of {@link java.util.Map.Entry#hashCode()}
146         * 
147         * @return a suitable hash code
148         */
149        public int hashCode() {
150            return (getKey() == null ? 0 : getKey().hashCode()) ^
151                   (getValue() == null ? 0 : getValue().hashCode()); 
152        }
153    
154        /**
155         * Written to match the output of the Map.Entry's used in 
156         * a {@link java.util.HashMap}. 
157         * @since 3.0
158         */
159        public String toString() {
160            return ""+getKey()+"="+getValue();
161        }
162    
163    }