org.jfree.util.HashNMap Maven / Gradle / Ivy
Go to download
Show more of this group Show more artifacts with this name
Show all versions of jcommon Show documentation
Show all versions of jcommon Show documentation
JCommon is a free general purpose Java class library that is used in
several projects at www.jfree.org, including JFreeChart and
JFreeReport.
/* ========================================================================
* JCommon : a free general purpose class library for the Java(tm) platform
* ========================================================================
*
* (C) Copyright 2000-2005, by Object Refinery Limited and Contributors.
*
* Project Info: http://www.jfree.org/jcommon/index.html
*
* This library is free software; you can redistribute it and/or modify it
* under the terms of the GNU Lesser General Public License as published by
* the Free Software Foundation; either version 2.1 of the License, or
* (at your option) any later version.
*
* This library is distributed in the hope that it will be useful, but
* WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
* or FITNESS FOR A PARTICULAR PURPOSE. See the GNU Lesser General Public
* License for more details.
*
* You should have received a copy of the GNU Lesser General Public
* License along with this library; if not, write to the Free Software
* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301,
* USA.
*
* [Java is a trademark or registered trademark of Sun Microsystems, Inc.
* in the United States and other countries.]
*
* -------------
* HashNMap.java
* -------------
* (C)opyright 2002-2005, by Thomas Morgner and Contributors.
*
* Original Author: Thomas Morgner;
* Contributor(s): David Gilbert (for Object Refinery Limited);
*
* $Id: HashNMap.java,v 1.7 2005/10/18 13:24:19 mungady Exp $
*
* Changes
* -------
* 20-May-2002 : Initial version
* 10-Dec-2002 : Minor Javadoc updates (DG);
* 29-Jul-2004 : Replaced 'enum' variable name (reserved word in JDK 1.5) (DG);
* 12-Mar-2005 : Some performance improvements, this implementation is no
* longer forced to use ArrayLists, add/put behaviour changed to
* fit the common behaviour of collections.
*
*/
package org.jfree.util;
import java.io.Serializable;
import java.util.ArrayList;
import java.util.HashMap;
import java.util.Iterator;
import java.util.List;
import java.util.NoSuchElementException;
import java.util.Set;
/**
* The HashNMap can be used to store multiple values by a single key value. The
* values stored can be retrieved using a direct query or by creating an
* enumeration over the stored elements.
*
* @author Thomas Morgner
*/
public class HashNMap implements Serializable, Cloneable {
/** Serialization support. */
private static final long serialVersionUID = -670924844536074826L;
/**
* An helper class to implement an empty iterator. This iterator will always
* return false when hasNext is called.
*/
private static final class EmptyIterator implements Iterator {
/**
* DefaultConstructor.
*/
private EmptyIterator() {
super();
}
/**
* Returns true if the iteration has more elements. (In other
* words, returns true if next would return an element
* rather than throwing an exception.)
*
* @return true if the iterator has more elements.
*/
public boolean hasNext() {
return false;
}
/**
* Returns the next element in the iteration.
*
* @return the next element in the iteration.
* @throws NoSuchElementException iteration has no more elements.
*/
public Object next() {
throw new NoSuchElementException("This iterator is empty.");
}
/**
* Removes from the underlying collection the last element returned by the
* iterator (optional operation). This method can be called only once per
* call to next. The behavior of an iterator is unspecified if
* the underlying collection is modified while the iteration is in
* progress in any way other than by calling this method.
*
* @throws UnsupportedOperationException if the remove
* operation is not supported by this Iterator.
* @throws IllegalStateException if the next method has not
* yet been called, or the remove method has already
* been called after the last call to the next
* method.
*/
public void remove() {
throw new UnsupportedOperationException("This iterator is empty, no remove supported.");
}
}
/**
* A singleton instance of the empty iterator. This object can be safely
* shared.
*/
private static final Iterator EMPTY_ITERATOR = new EmptyIterator();
/**
* The underlying storage.
*/
private HashMap table;
/**
* An empty array.
*/
private static final Object[] EMPTY_ARRAY = new Object[0];
/**
* Default constructor.
*/
public HashNMap() {
this.table = new HashMap();
}
/**
* Returns a new empty list.
*
* @return A new empty list.
*/
protected List createList() {
return new ArrayList();
}
/**
* Inserts a new key/value pair into the map. If such a pair already
* exists, it gets replaced with the given values.
*
* @param key the key.
* @param val the value.
* @return A boolean.
*/
public boolean put(final Object key, final Object val) {
final List v = (List) this.table.get(key);
if (v == null) {
final List newList = createList();
newList.add(val);
this.table.put(key, newList);
return true;
}
else {
v.clear();
return v.add(val);
}
}
/**
* Adds a new key/value pair into this map. If the key is not yet in the
* map, it gets added to the map and the call is equal to
* put(Object,Object).
*
* @param key the key.
* @param val the value.
* @return true, if the value has been added, false otherwise
*/
public boolean add(final Object key, final Object val) {
final List v = (List) this.table.get(key);
if (v == null) {
put(key, val);
return true;
}
else {
return v.add(val);
}
}
/**
* Retrieves the first value registered for an key or null if there was no
* such key in the list.
*
* @param key the key.
* @return the value.
*/
public Object getFirst(final Object key) {
return get(key, 0);
}
/**
* Retrieves the n-th value registered for an key or null if there was no
* such key in the list. An index out of bounds exception is thrown if
* there are less than n elements registered to this key.
*
* @param key the key.
* @param n the index.
* @return the object.
*/
public Object get(final Object key, final int n) {
final List v = (List) this.table.get(key);
if (v == null) {
return null;
}
return v.get(n);
}
/**
* Returns an iterator over all elements registered to the given key.
*
* @param key the key.
* @return an iterator.
*/
public Iterator getAll(final Object key) {
final List v = (List) this.table.get(key);
if (v == null) {
return EMPTY_ITERATOR;
}
return v.iterator();
}
/**
* Returns all registered keys as an enumeration.
*
* @return an enumeration of the keys.
*/
public Iterator keys() {
return this.table.keySet().iterator();
}
/**
* Returns all registered keys as set.
*
* @return a set of keys.
*/
public Set keySet() {
return this.table.keySet();
}
/**
* Removes the key/value pair from the map. If the removed entry was the
* last entry for this key, the key gets also removed.
*
* @param key the key.
* @param value the value.
* @return true, if removing the element was successfull, false otherwise.
*/
public boolean remove(final Object key, final Object value) {
final List v = (List) this.table.get(key);
if (v == null) {
return false;
}
if (!v.remove(value)) {
return false;
}
if (v.size() == 0) {
this.table.remove(key);
}
return true;
}
/**
* Removes all elements for the given key.
*
* @param key the key.
*/
public void removeAll(final Object key) {
this.table.remove(key);
}
/**
* Clears all keys and values of this map.
*/
public void clear() {
this.table.clear();
}
/**
* Tests whether this map contains the given key.
*
* @param key the key.
* @return true if the key is contained in the map
*/
public boolean containsKey(final Object key) {
return this.table.containsKey(key);
}
/**
* Tests whether this map contains the given value.
*
* @param value the value.
* @return true if the value is registered in the map for an key.
*/
public boolean containsValue(final Object value) {
final Iterator e = this.table.values().iterator();
boolean found = false;
while (e.hasNext() && !found) {
final List v = (List) e.next();
found = v.contains(value);
}
return found;
}
/**
* Tests whether this map contains the given value.
*
* @param value the value.
* @param key the key under which to find the value
* @return true if the value is registered in the map for an key.
*/
public boolean containsValue(final Object key, final Object value) {
final List v = (List) this.table.get(key);
if (v == null) {
return false;
}
return v.contains(value);
}
/**
* Tests whether this map contains the given key or value.
*
* @param value the value.
* @return true if the key or value is contained in the map
*/
public boolean contains(final Object value) {
if (containsKey(value)) {
return true;
}
return containsValue(value);
}
/**
* Creates a deep copy of this HashNMap.
*
* @return a clone.
* @throws CloneNotSupportedException this should never happen.
*/
public Object clone() throws CloneNotSupportedException {
final HashNMap map = (HashNMap) super.clone();
map.table = new HashMap();
final Iterator iterator = keys();
while (iterator.hasNext()) {
final Object key = iterator.next();
final List list = (List) map.table.get(key);
if (list != null) {
map.table.put(key, ObjectUtilities.clone(list));
}
}
return map;
}
/**
* Returns the contents for the given key as object array. If there were
* no objects registered with that key, an empty object array is returned.
*
* @param key the key.
* @param data the object array to receive the contents.
* @return the contents.
*/
public Object[] toArray(final Object key, final Object[] data) {
if (key == null) {
throw new NullPointerException("Key must not be null.");
}
final List list = (List) this.table.get(key);
if (list != null) {
return list.toArray(data);
}
if (data.length > 0) {
data[0] = null;
}
return data;
}
/**
* Returns the contents for the given key as object array. If there were
* no objects registered with that key, an empty object array is returned.
*
* @param key the key.
* @return the contents.
*/
public Object[] toArray(final Object key) {
if (key == null) {
throw new NullPointerException("Key must not be null.");
}
final List list = (List) this.table.get(key);
if (list != null) {
return list.toArray();
}
return EMPTY_ARRAY;
}
/**
* Returns the number of elements registered with the given key.
*
* @param key the key.
* @return the number of element for this key, or 0 if there are no elements
* registered.
*/
public int getValueCount(final Object key) {
if (key == null) {
throw new NullPointerException("Key must not be null.");
}
final List list = (List) this.table.get(key);
if (list != null) {
return list.size();
}
return 0;
}
}
© 2015 - 2024 Weber Informatics LLC | Privacy Policy