org.apache.commons.collections.keyvalue.MultiKey Maven / Gradle / Ivy
Show all versions of jt-all Show documentation
/* ====================================================================
* The Apache Software License, Version 1.1
*
* Copyright (c) 2003-2004 The Apache Software Foundation. All rights
* reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
*
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
*
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in
* the documentation and/or other materials provided with the
* distribution.
*
* 3. The end-user documentation included with the redistribution, if
* any, must include the following acknowledgement:
* "This product includes software developed by the
* Apache Software Foundation (http://www.apache.org/)."
* Alternately, this acknowledgement may appear in the software itself,
* if and wherever such third-party acknowledgements normally appear.
*
* 4. The names "The Jakarta Project", "Commons", and "Apache Software
* Foundation" must not be used to endorse or promote products derived
* from this software without prior written permission. For written
* permission, please contact [email protected].
*
* 5. Products derived from this software may not be called "Apache"
* nor may "Apache" appear in their names without prior written
* permission of the Apache Software Foundation.
*
* THIS SOFTWARE IS PROVIDED ``AS IS'' AND ANY EXPRESSED OR IMPLIED
* WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
* OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
* DISCLAIMED. IN NO EVENT SHALL THE APACHE SOFTWARE FOUNDATION OR
* ITS CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
* SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
* LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF
* USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
* ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
* OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
* OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
* SUCH DAMAGE.
* ====================================================================
*
* This software consists of voluntary contributions made by many
* individuals on behalf of the Apache Software Foundation. For more
* information on the Apache Software Foundation, please see
* MultiKey allows multiple map keys to be merged together.
*
* The purpose of this class is to avoid the need to write code to handle
* maps of maps. An example might be the need to lookup a filename by
* key and locale. The typical solution might be nested maps. This class
* can be used instead by creating an instance passing in the key and locale.
*
* @since Commons Collections 3.0
* @version $Revision: 1.3 $ $Date: 2004/01/14 21:43:15 $
*
* @author Howard Lewis Ship
* @author Stephen Colebourne
*/
public class MultiKey implements Serializable {
/** Serialisation version */
private static final long serialVersionUID = 4465448607415788805L;
/** The individual keys */
private final Object[] keys;
/** The cached hashCode */
private final int hashCode;
/**
* Constructor taking two keys.
*
* @param key1 the first key
* @param key2 the second key
*/
public MultiKey(Object key1, Object key2) {
this(new Object[] {key1, key2}, false);
}
/**
* Constructor taking three keys.
*
* @param key1 the first key
* @param key2 the second key
* @param key3 the third key
*/
public MultiKey(Object key1, Object key2, Object key3) {
this(new Object[] {key1, key2, key3}, false);
}
/**
* Constructor taking four keys.
*
* @param key1 the first key
* @param key2 the second key
* @param key3 the third key
* @param key4 the fourth key
*/
public MultiKey(Object key1, Object key2, Object key3, Object key4) {
this(new Object[] {key1, key2, key3, key4}, false);
}
/**
* Constructor taking five keys.
*
* @param key1 the first key
* @param key2 the second key
* @param key3 the third key
* @param key4 the fourth key
* @param key5 the fifth key
*/
public MultiKey(Object key1, Object key2, Object key3, Object key4, Object key5) {
this(new Object[] {key1, key2, key3, key4, key5}, false);
}
/**
* Constructor taking an array of keys.
*
* @param keys the array of keys
* @throws IllegalArgumentException if the key array is null
*/
public MultiKey(Object[] keys) {
this(keys, true);
}
/**
* Constructor taking an array of keys.
*
* If the array is not copied, then it must not be modified.
*
* @param keys the array of keys
* @param makeCopy true to copy the array, false to assign it
* @throws IllegalArgumentException if the key array is null
*/
protected MultiKey(Object[] keys, boolean makeCopy) {
super();
if (keys == null) {
throw new IllegalArgumentException("The array of keys must not be null");
}
if (makeCopy) {
this.keys = (Object[]) keys.clone();
} else {
this.keys = keys;
}
int total = 0;
for (int i = 0; i < keys.length; i++) {
if (keys[i] != null) {
if (i == 0) {
total = keys[i].hashCode();
} else {
total ^= keys[i].hashCode();
}
}
}
hashCode = total;
}
/**
* Gets a copy of the individual keys.
*
* @return the individual keys
*/
public Object[] getKeys() {
return (Object[]) keys.clone();
}
/**
* Compares this object to another.
*
* To be equal, the other object must be a MultiKey with the
* same number of keys which are also equal.
*
* @param other the other object to compare to
* @return true if equal
*/
public boolean equals(Object other) {
if (other == this) {
return true;
}
if (other instanceof MultiKey) {
MultiKey otherMulti = (MultiKey) other;
return Arrays.equals(keys, otherMulti.keys);
}
return false;
}
/**
* Gets the combined hash code that is computed from all the keys.
*
* This value is computed once and then cached, so elements should not
* change their hash codes once created (note that this is the same
* constraint that would be used if the individual keys elements were
* themselves {@link java.util.Map Map} keys.
*
* @return the hash code
*/
public int hashCode() {
return hashCode;
}
/**
* Gets a debugging string version of the key.
*
* @return a debugging string
*/
public String toString() {
return "MultiKey" + Arrays.asList(keys).toString();
}
}