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Commons Collections example source code file (CaseInsensitiveMap.java)

This example Commons Collections source code file (CaseInsensitiveMap.java) is included in the DevDaily.com "Java Source Code Warehouse" project. The intent of this project is to help you "Learn Java by Example" TM.

Java - Commons Collections tags/keywords

abstracthashedmap, caseinsensitivemap, caseinsensitivemap, classnotfoundexception, cloneable, default_load_factor, default_threshold, io, ioexception, ioexception, object, object, serializable, serializable, util

The Commons Collections CaseInsensitiveMap.java source code

/*
 *  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.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 <code>Map.
 * <p>
 * As entries are added to the map, keys are converted to all lowercase. A new 
 * key is compared to existing keys by comparing <code>newKey.toString().toLower()
 * to the lowercase values in the current <code>KeySet.
 * <p>
 * Null keys are supported.  
 * <p>
 * The <code>keySet() method returns all lowercase keys, or nulls.
 * <p>
 * Example:
 * <pre>
 *  Map map = new CaseInsensitiveMap();
 *  map.put("One", "One");
 *  map.put("Two", "Two");
 *  map.put(null, "Three");
 *  map.put("one", "Four");
 * </code>
* creates a <code>CaseInsensitiveMap with three entries.
* <code>map.get(null) returns "Three" and map.get("ONE") * returns <code>"Four". The Set returned by keySet() * equals <code>{"one", "two", null}. * <p> * <strong>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 Commons Collections 3.0 * @version $Revision: 646777 $ $Date: 2008-04-10 13:33:15 +0100 (Thu, 10 Apr 2008) $ * * @author Commons-Collections team */ 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 less than one */ public CaseInsensitiveMap(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 CaseInsensitiveMap(int initialCapacity, float loadFactor) { super(initialCapacity, loadFactor); } /** * 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 {@link AbstractHashedMap} to convert keys to * lower case. * <p> * Returns null if key is null. * * @param key the key convert * @return the converted key */ protected Object convertKey(Object key) { if (key != null) { return key.toString().toLowerCase(); } else { return AbstractHashedMap.NULL; } } //----------------------------------------------------------------------- /** * 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); } }

Other Commons Collections examples (source code examples)

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