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 *      http://www.apache.org/licenses/LICENSE-2.0
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 *  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.
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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 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 map = new CaseInsensitiveMap();
 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}.

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 Collections.synchronizedMap(Map<Object,Object>). This class may throw exceptions when accessed by concurrent threads without synchronization. 
Author:
Commons-Collections team
Since:
Commons Collections 3.0
Version:
$Revision: 1713181 $ $Date: 2015-11-07 22:17:00 +0100 (Sat, 07 Nov 2015) $/**
 * A case-insensitive <code>Map</code>.
 * <p>
 * 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.
 * <p>
 * Null keys are supported.  
 * <p>
 * The <code>keySet()</code> method returns all lowercase keys, or nulls.
 * <p>
 * Example:
 * <pre><code>
 *  Map map = new CaseInsensitiveMap();
 *  map.put("One", "One");
 *  map.put("Two", "Two");
 *  map.put(null, "Three");
 *  map.put("one", "Four");
 * </code></pre>
 * creates a <code>CaseInsensitiveMap</code> with three entries.<br>
 * <code>map.get(null)</code> returns <code>"Three"</code> and <code>map.get("ONE")</code>
 * returns <code>"Four".</code>  The <code>Set</code> returned by <code>keySet()</code>
 * equals <code>{"one", "two", null}.</code>
 * <p>
 * <strong>Note that CaseInsensitiveMap is not synchronized and is not thread-safe.</strong>
 * 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 Commons Collections 3.0
 * @version $Revision: 1713181 $ $Date: 2015-11-07 22:17:00 +0100 (Sat, 07 Nov 2015) $
 *
 * @author Commons-Collections team
 */
public class CaseInsensitiveMap extends AbstractHashedMap implements Serializable, Cloneable {

    
Serialisation version /** Serialisation version */
    private static final long serialVersionUID = -7074655917369299456L;

    
Constructs a new empty map with default size and load factor.
/**
     * 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. 
Params:
initialCapacity –  the initial capacity
Throws:
IllegalArgumentException – if the initial capacity is less than one/**
     * 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 CaseInsensitiveMap(int initialCapacity) {
        super(initialCapacity);
    }

    
Constructs a new, empty map with the specified initial capacity and
load factor. 
Params:
initialCapacity –  the initial capacity
loadFactor –  the load factor
Throws:
IllegalArgumentException – if the initial capacity is less than one
IllegalArgumentException – if the load factor is less than zero/**
     * 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 CaseInsensitiveMap(int initialCapacity, 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).
Params:
map –  the map to copy
Throws:
NullPointerException – if the map is null/**
     * Constructor copying elements from another map.
     * <p>
     * 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(Map map) {
        super(map);
    }

    //-----------------------------------------------------------------------
    
Overrides convertKey() from AbstractHashedMap to convert keys to lower case. 
 Returns AbstractHashedMap.NULL if key is null. 
Params:
key –  the key convert
Returns:
the converted key/**
     * Overrides convertKey() from {@link AbstractHashedMap} to convert keys to 
     * lower case.
     * <p>
     * Returns {@link AbstractHashedMap#NULL} if key is null.
     *
     * @param key  the key convert
     * @return the converted key
     */
    protected Object convertKey(Object key) {
        if (key != null) {
            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);
        } else {
            return AbstractHashedMap.NULL;
        }
    }   

    //-----------------------------------------------------------------------
    
Clones the map without cloning the keys or values.
Returns:
a shallow clone/**
     * 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.
/**
     * 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.
/**
     * Read the map in using a custom routine.
     */
    private void readObject(ObjectInputStream in) throws IOException, ClassNotFoundException {
        in.defaultReadObject();
        doReadObject(in);
    }
 
}