/*******************************************************************************
* Copyright (c) 1998, 2015 Oracle and/or its affiliates. All rights reserved.
* This program and the accompanying materials are made available under the
* terms of the Eclipse Public License v1.0 and Eclipse Distribution License v. 1.0
* which accompanies this distribution.
* The Eclipse Public License is available at http://www.eclipse.org/legal/epl-v10.html
* and the Eclipse Distribution License is available at
* http://www.eclipse.org/org/documents/edl-v10.php.
*
* Contributors:
* Oracle - initial API and implementation from Oracle TopLink
******************************************************************************/
package org.eclipse.persistence.tools.workbench.utility.iterators;
import java.util.ListIterator;
import java.util.NoSuchElementException;
import org.eclipse.persistence.tools.workbench.utility.ClassTools;
/**
* A <code>NullListIterator</code> is just that.
*/
public final class NullListIterator implements ListIterator {
// singleton
private static NullListIterator INSTANCE;
/**
* Return the singleton.
*/
public static synchronized ListIterator instance() {
if (INSTANCE == null) {
INSTANCE = new NullListIterator();
}
return INSTANCE;
}
/**
* Ensure non-instantiability.
*/
private NullListIterator() {
super();
}
/**
* @see java.util.ListIterator#add(Object)
*/
public void add(Object o) {
throw new UnsupportedOperationException();
}
/**
* @see java.util.Iterator#hasNext()
*/
public boolean hasNext() {
return false;
}
/**
* @see java.util.ListIterator#hasPrevious()
*/
public boolean hasPrevious() {
return false;
}
/**
* @see java.util.Iterator#next()
*/
public Object next() {
throw new NoSuchElementException();
}
/**
* @see java.util.ListIterator#nextIndex()
*/
public int nextIndex() {
return 0;
}
/**
* @see java.util.ListIterator#previous()
*/
public Object previous() {
throw new NoSuchElementException();
}
/**
* @see java.util.ListIterator#previousIndex()
*/
public int previousIndex() {
return -1;
}
/**
* @see java.util.Iterator#remove()
*/
public void remove() {
throw new UnsupportedOperationException();
}
/**
* @see java.util.ListIterator#set(Object)
*/
public void set(Object o) {
throw new UnsupportedOperationException();
}
/**
* @see Object#toString()
*/
public String toString() {
return ClassTools.shortClassNameForObject(this);
}
}