Mega Code Archive
One Item Set
<![CDATA[
/* $Id$
*
* Behavior Protocols Tools - Parsers, Transformations
* Copyright (C) 2006-2007 DSRG, Charles University in Prague
* http://dsrg.mff.cuni.cz/
*
* 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
*
*/
import java.io.Serializable;
import java.util.AbstractCollection;
import java.util.Iterator;
import java.util.NoSuchElementException;
/**
*
* @author thorm
*/
public class OneItemSet<E> extends AbstractCollection<E> implements Serializable{
public boolean add(E i) {
if (item == i) {
return false;
}
if (item == null) {
item = i;
return true;
}
throw new IllegalArgumentException();
}
public Iterator<E> iterator() {
return new Iterator() {
public boolean hasNext() {
return hasNxt;
}
public E next() {
if (hasNxt) {
hasNxt = false;
return item;
}
throw new NoSuchElementException();
}
public void remove() {
item = null;
}
boolean hasNxt = true;
};
}
public int size() {
return (item == null) ? 0 : 1;
}
public int hashCode() {
return item.hashCode();
}
public boolean equals(Object o) {
return (o instanceof OneItemSet) && item.equals(((OneItemSet) o).item);
}
E item;
}
]]>