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/* EmptyEnumeration.java -- a constant empty enumeration
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Copyright (C) 2001, 2002 Free Software Foundation, Inc.
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This file is part of GNU Classpath.
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GNU Classpath is free software; you can redistribute it and/or modify
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it under the terms of the GNU General Public License as published by
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the Free Software Foundation; either version 2, or (at your option)
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GNU Classpath is distributed in the hope that it will be useful, but
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WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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General Public License for more details.
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You should have received a copy of the GNU General Public License
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along with GNU Classpath; see the file COPYING. If not, write to the
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Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
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Linking this library statically or dynamically with other modules is
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making a combined work based on this library. Thus, the terms and
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conditions of the GNU General Public License cover the whole
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As a special exception, the copyright holders of this library give you
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permission to link this library with independent modules to produce an
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executable, regardless of the license terms of these independent
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modules, and to copy and distribute the resulting executable under
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terms of your choice, provided that you also meet, for each linked
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independent module, the terms and conditions of the license of that
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module. An independent module is a module which is not derived from
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or based on this library. If you modify this library, you may extend
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this exception to your version of the library, but you are not
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obligated to do so. If you do not wish to do so, delete this
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exception statement from your version. */
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package gnu.java.util;
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import java.io.Serializable;
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import java.util.Enumeration;
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import java.util.NoSuchElementException;
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* This is a helper class that produces an empty Enumerations. There is only
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* one instance of this class that can be used whenever one needs a
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* non-null but empty enumeration. Using this class prevents multiple
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* small objects and inner classes. <code>getInstance()</code> returns
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* the only instance of this class. It can be shared by multiple objects and
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* @author Mark Wielaard (mark@klomp.org)
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public final class EmptyEnumeration implements Enumeration, Serializable
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/** The only instance of this class */
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private static final EmptyEnumeration instance = new EmptyEnumeration();
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* Private constructor that creates a new empty Enumeration.
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private EmptyEnumeration()
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* Returns the only instance of this class.
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* It can be shared by multiple objects and threads.
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* @return the common empty enumeration
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public static EmptyEnumeration getInstance()
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* Returns false, since there are no elements.
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public boolean hasMoreElements()
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* Always throws <code>NoSuchElementException</code>, since it is empty.
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* @throws NoSuchElementException this is empty
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public Object nextElement()
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throw new NoSuchElementException();