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/*******************************************************************************
* Copyright (c) 2008, 2010 Oracle. All rights reserved.
* This program and the accompanying materials are made available under the
* terms of the Eclipse Public License v1.0, which accompanies this distribution
* and is available at http://www.eclipse.org/legal/epl-v10.html.
*
* Contributors:
* Oracle - initial API and implementation
******************************************************************************/
package org.eclipse.jpt.utility.internal.iterables;
import java.io.Serializable;
import java.util.Iterator;
import org.eclipse.jpt.utility.internal.iterators.EmptyIterator;
/**
* An <code>EmptyIterable</code> is just that.
* Maybe just a touch better-performing than {@link java.util.Collections#EMPTY_SET}
* since we don't create a new {@link Iterator} every time {@link #iterator()} is called.
* (Not sure why they do that....)
*
* @param <E> the type of elements returned by the iterable's iterator
*
* @see EmptyIterator
* @see EmptyListIterable
*/
public final class EmptyIterable<E>
implements Iterable<E>, Serializable
{
// singleton
@SuppressWarnings("rawtypes")
private static final Iterable INSTANCE = new EmptyIterable();
/**
* Return the singleton.
*/
@SuppressWarnings("unchecked")
public static <T> Iterable<T> instance() {
return INSTANCE;
}
/**
* Ensure single instance.
*/
private EmptyIterable() {
super();
}
public Iterator<E> iterator() {
return EmptyIterator.instance();
}
@Override
public String toString() {
return this.getClass().getSimpleName();
}
private static final long serialVersionUID = 1L;
private Object readResolve() {
// replace this object with the singleton
return INSTANCE;
}
}
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