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/*
 * Licensed to the Apache Software Foundation (ASF) under one or more
 * contributor license agreements.  See the NOTICE file distributed with
 * this work for additional information regarding copyright ownership.
 * The ASF licenses this file to You 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.collections4.map;

import java.io.IOException;
import java.io.ObjectInputStream;
import java.io.ObjectOutputStream;
import java.io.Serializable;
import java.util.Map;

/**
 * A case-insensitive Map.
 * 

* Before keys are added to the map or compared to other existing keys, they are converted * to all lowercase in a locale-independent fashion by using information from the Unicode * data file. *

* Null keys are supported. *

* The keySet() method returns all lowercase keys, or nulls. *

* Example: *


 *  Map<String, String> map = new CaseInsensitiveMap<String, String>();
 *  map.put("One", "One");
 *  map.put("Two", "Two");
 *  map.put(null, "Three");
 *  map.put("one", "Four");
 * 
* creates a CaseInsensitiveMap with three entries.
* map.get(null) returns "Three" and map.get("ONE") * returns "Four". The Set returned by keySet() * equals {"one", "two", null}. *

* 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. In particular, you can't * use decorators like {@link ListOrderedMap} on it, which silently assume that these * contracts are fulfilled. *

* Note that CaseInsensitiveMap is not synchronized and is not thread-safe. * If you wish to use this map from multiple threads concurrently, you must use * appropriate synchronization. The simplest approach is to wrap this map * using {@link java.util.Collections#synchronizedMap(Map)}. This class may throw * exceptions when accessed by concurrent threads without synchronization. * * @since 3.0 * @version $Id: CaseInsensitiveMap.java 1533984 2013-10-20 21:12:51Z tn $ */ public class CaseInsensitiveMap extends AbstractHashedMap implements Serializable, Cloneable { /** Serialisation version */ private static final long serialVersionUID = -7074655917369299456L; /** * Constructs a new empty map with default size and load factor. */ public CaseInsensitiveMap() { 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 negative */ public CaseInsensitiveMap(final 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 negative * @throws IllegalArgumentException if the load factor is less than zero */ public CaseInsensitiveMap(final int initialCapacity, final float loadFactor) { super(initialCapacity, loadFactor); } /** * Constructor copying elements from another map. *

* Keys will be converted to lower case strings, which may cause * some entries to be removed (if string representation of keys differ * only by character case). * * @param map the map to copy * @throws NullPointerException if the map is null */ public CaseInsensitiveMap(final Map map) { super(map); } //----------------------------------------------------------------------- /** * Overrides convertKey() from {@link AbstractHashedMap} to convert keys to * lower case. *

* Returns {@link AbstractHashedMap#NULL} if key is null. * * @param key the key convert * @return the converted key */ @Override protected Object convertKey(final Object key) { if (key != null) { final char[] chars = key.toString().toCharArray(); for (int i = chars.length - 1; i >= 0; i--) { chars[i] = Character.toLowerCase(Character.toUpperCase(chars[i])); } return new String(chars); } return AbstractHashedMap.NULL; } //----------------------------------------------------------------------- /** * Clones the map without cloning the keys or values. * * @return a shallow clone */ @Override public CaseInsensitiveMap clone() { return (CaseInsensitiveMap) super.clone(); } /** * Write the map out using a custom routine. */ private void writeObject(final ObjectOutputStream out) throws IOException { out.defaultWriteObject(); doWriteObject(out); } /** * Read the map in using a custom routine. */ private void readObject(final ObjectInputStream in) throws IOException, ClassNotFoundException { in.defaultReadObject(); doReadObject(in); } }





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