Hibernate example source code file (IdentitySet.java)

This example Hibernate source code file (IdentitySet.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 - Hibernate tags/keywords

dump_value, dump_value, identityhashmap, identityhashmap, identityset, iterator, iterator, object, object, set, unsupportedoperationexception, util

The Hibernate IdentitySet.java source code

/*
 * Hibernate, Relational Persistence for Idiomatic Java
 *
 * Copyright (c) 2008, Red Hat Middleware LLC or third-party contributors as
 * indicated by the @author tags or express copyright attribution
 * statements applied by the authors.  All third-party contributions are
 * distributed under license by Red Hat Middleware LLC.
 *
 * This copyrighted material is made available to anyone wishing to use, modify,
 * copy, or redistribute it subject to the terms and conditions of the GNU
 * Lesser General Public License, as published by the Free Software Foundation.
 *
 * This program 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 distribution; if not, write to:
 * Free Software Foundation, Inc.
 * 51 Franklin Street, Fifth Floor
 * Boston, MA  02110-1301  USA
 *
 */
package org.hibernate.internal.util.collections;

import java.util.Collection;
import java.util.IdentityHashMap;
import java.util.Iterator;
import java.util.Set;

/**
 * Set implementation that use == instead of equals() as its comparison
 * mechanism.  This is achieved by internally using an IdentityHashMap.
 *
 * @author Emmanuel Bernard
 */
public class IdentitySet implements Set {
	private static final Object DUMP_VALUE = new Object();

	private final IdentityHashMap map;

	/**
	 * Create an IdentitySet with default sizing.
	 */
	public IdentitySet() {
		this.map = new IdentityHashMap();
	}

	/**
	 * Create an IdentitySet with the given sizing.
	 *
	 * @param sizing The sizing of the set to create.
	 */
	public IdentitySet(int sizing) {
		this.map = new IdentityHashMap( sizing );
	}

	public int size() {
		return map.size();
	}

	public boolean isEmpty() {
		return map.isEmpty();
	}

	public boolean contains(Object o) {
		return map.get( o ) == DUMP_VALUE;
	}

	public Iterator iterator() {
		return map.entrySet().iterator();
	}

	public Object[] toArray() {
		return map.entrySet().toArray();
	}

	public Object[] toArray(Object[] a) {
		return map.entrySet().toArray( a );
	}

	public boolean add(Object o) {
		return map.put( o, DUMP_VALUE ) == null;
	}

	public boolean remove(Object o) {
		return map.remove( o ) == DUMP_VALUE;
	}

	public boolean containsAll(Collection c) {
		Iterator it = c.iterator();
		while ( it.hasNext() ) {
			if ( !map.containsKey( it.next() ) ) {
				return false;
			}
		}
		return true;
	}

	public boolean addAll(Collection c) {
		Iterator it = c.iterator();
		boolean changed = false;
		while ( it.hasNext() ) {
			if ( this.add( it.next() ) ) {
				changed = true;
			}
		}
		return changed;
	}

	public boolean retainAll(Collection c) {
		//doable if needed
		throw new UnsupportedOperationException();
	}

	public boolean removeAll(Collection c) {
		Iterator it = c.iterator();
		boolean changed = false;
		while ( it.hasNext() ) {
			if ( this.remove( it.next() ) ) {
				changed = true;
			}
		}
		return changed;
	}

	public void clear() {
		map.clear();
	}
}