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/*******************************************************************************
* Copyright (c) 2005, 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.common.utility.internal.enumerations;
import java.util.Enumeration;
import java.util.NoSuchElementException;
/**
* An <code>EmptyEnumeration</code> is just that.
*
* @param <E> the type of elements returned by the enumeration
*/
public final class EmptyEnumeration<E>
implements Enumeration<E>
{
// singleton
@SuppressWarnings("rawtypes")
private static final EmptyEnumeration INSTANCE = new EmptyEnumeration();
/**
* Return the singleton.
*/
@SuppressWarnings("unchecked")
public static <T> Enumeration<T> instance() {
return INSTANCE;
}
/**
* Ensure single instance.
*/
private EmptyEnumeration() {
super();
}
public boolean hasMoreElements() {
return false;
}
public E nextElement() {
throw new NoSuchElementException();
}
@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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