gnu.java.util

Class EmptyEnumeration<T>

Implemented Interfaces:
Enumeration<E>, Serializable

public final class EmptyEnumeration<T>
extends Object
implements Enumeration<E>, Serializable

This is a helper class that produces an empty Enumerations. There is only one instance of this class that can be used whenever one needs a non-null but empty enumeration. Using this class prevents multiple small objects and inner classes. getInstance() returns the only instance of this class. It can be shared by multiple objects and threads.
See Also:
Serialized Form

Method Summary

static EmptyEnumeration
getInstance()
Returns an instance of this class for Object.
boolean
hasMoreElements()
Returns false, since there are no elements.
T
nextElement()
Always throws NoSuchElementException, since it is empty.

Methods inherited from class java.lang.Object

clone, equals, extends Object> getClass, finalize, hashCode, notify, notifyAll, toString, wait, wait, wait

Method Details

getInstance

public static EmptyEnumeration getInstance()
Returns an instance of this class for Object. It can be shared by multiple objects and threads.
Returns:
the common empty enumeration

hasMoreElements

public boolean hasMoreElements()
Returns false, since there are no elements.
Specified by:
hasMoreElements in interface Enumeration<E>
Returns:
false

nextElement

public T nextElement()
Always throws NoSuchElementException, since it is empty.
Specified by:
nextElement in interface Enumeration<E>
Throws:
NoSuchElementException - this is empty

EmptyEnumeration.java -- a constant empty enumeration Copyright (C) 2001, 2002 Free Software Foundation, Inc. This file is part of GNU Classpath. GNU Classpath is free software; you can redistribute it and/or modify it under the terms of the GNU General Public License as published by the Free Software Foundation; either version 2, or (at your option) any later version. GNU Classpath 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 General Public License for more details. You should have received a copy of the GNU General Public License along with GNU Classpath; see the file COPYING. If not, write to the Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA. Linking this library statically or dynamically with other modules is making a combined work based on this library. Thus, the terms and conditions of the GNU General Public License cover the whole combination. As a special exception, the copyright holders of this library give you permission to link this library with independent modules to produce an executable, regardless of the license terms of these independent modules, and to copy and distribute the resulting executable under terms of your choice, provided that you also meet, for each linked independent module, the terms and conditions of the license of that module. An independent module is a module which is not derived from or based on this library. If you modify this library, you may extend this exception to your version of the library, but you are not obligated to do so. If you do not wish to do so, delete this exception statement from your version.