- /*
- * Copyright 2003-2004 The Apache Software Foundation
- *
- * Licensed under the Apache 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.apache.org/licenses/LICENSE-2.0
- *
- * 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.apache.commons.collections.map;
-
- import java.io.IOException;
- import java.io.ObjectInputStream;
- import java.io.ObjectOutputStream;
- import java.io.Serializable;
- import java.util.Map;
-
- /**
- * A <code>Map</code> implementation that matches keys and values based
- * on <code>==</code> not <code>equals()</code>.
- * <p>
- * This map will violate the detail of various Map and map view contracts.
- * As a general rule, don't compare this map to other maps.
- *
- * @since Commons Collections 3.0
- * @version $Revision: 1.5 $ $Date: 2004/02/18 01:13:19 $
- *
- * @author java util HashMap
- * @author Stephen Colebourne
- */
- public class IdentityMap
- extends AbstractHashedMap implements Serializable, Cloneable {
-
- /** Serialisation version */
- private static final long serialVersionUID = 2028493495224302329L;
-
- /**
- * Constructs a new empty map with default size and load factor.
- */
- public IdentityMap() {
- super(DEFAULT_CAPACITY, DEFAULT_LOAD_FACTOR, DEFAULT_THRESHOLD);
- }
-
- /**
- * Constructs a new, empty map with the specified initial capacity.
- *
- * @param initialCapacity the initial capacity
- * @throws IllegalArgumentException if the initial capacity is less than one
- */
- public IdentityMap(int initialCapacity) {
- super(initialCapacity);
- }
-
- /**
- * Constructs a new, empty map with the specified initial capacity and
- * load factor.
- *
- * @param initialCapacity the initial capacity
- * @param loadFactor the load factor
- * @throws IllegalArgumentException if the initial capacity is less than one
- * @throws IllegalArgumentException if the load factor is less than zero
- */
- public IdentityMap(int initialCapacity, float loadFactor) {
- super(initialCapacity, loadFactor);
- }
-
- /**
- * Constructor copying elements from another map.
- *
- * @param map the map to copy
- * @throws NullPointerException if the map is null
- */
- public IdentityMap(Map map) {
- super(map);
- }
-
- //-----------------------------------------------------------------------
- /**
- * Gets the hash code for the key specified.
- * This implementation uses the identity hash code.
- *
- * @param key the key to get a hash code for
- * @return the hash code
- */
- protected int hash(Object key) {
- return System.identityHashCode(key);
- }
-
- /**
- * Compares two keys for equals.
- * This implementation uses <code>==</code>.
- *
- * @param key1 the first key to compare
- * @param key2 the second key to compare
- * @return true if equal by identity
- */
- protected boolean isEqualKey(Object key1, Object key2) {
- return (key1 == key2);
- }
-
- /**
- * Compares two values for equals.
- * This implementation uses <code>==</code>.
- *
- * @param value1 the first value to compare
- * @param value2 the second value to compare
- * @return true if equal by identity
- */
- protected boolean isEqualValue(Object value1, Object value2) {
- return (value1 == value2);
- }
-
- /**
- * Creates an entry to store the data.
- * This implementation creates an IdentityEntry instance.
- *
- * @param next the next entry in sequence
- * @param hashCode the hash code to use
- * @param key the key to store
- * @param value the value to store
- * @return the newly created entry
- */
- protected HashEntry createEntry(HashEntry next, int hashCode, Object key, Object value) {
- return new IdentityEntry(next, hashCode, key, value);
- }
-
- //-----------------------------------------------------------------------
- /**
- * HashEntry
- */
- protected static class IdentityEntry extends HashEntry {
-
- protected IdentityEntry(HashEntry next, int hashCode, Object key, Object value) {
- super(next, hashCode, key, value);
- }
-
- public boolean equals(Object obj) {
- if (obj == this) {
- return true;
- }
- if (obj instanceof Map.Entry == false) {
- return false;
- }
- Map.Entry other = (Map.Entry) obj;
- return
- (getKey() == other.getKey()) &&
- (getValue() == other.getValue());
- }
-
- public int hashCode() {
- return System.identityHashCode(getKey()) ^
- System.identityHashCode(getValue());
- }
- }
-
- //-----------------------------------------------------------------------
- /**
- * Clones the map without cloning the keys or values.
- *
- * @return a shallow clone
- */
- public Object clone() {
- return super.clone();
- }
-
- /**
- * Write the map out using a custom routine.
- */
- private void writeObject(ObjectOutputStream out) throws IOException {
- out.defaultWriteObject();
- doWriteObject(out);
- }
-
- /**
- * Read the map in using a custom routine.
- */
- private void readObject(ObjectInputStream in) throws IOException, ClassNotFoundException {
- in.defaultReadObject();
- doReadObject(in);
- }
-
- }