001    /*
002     *  This file is part of the Jikes RVM project (http://jikesrvm.org).
003     *
004     *  This file is licensed to You under the Eclipse Public License (EPL);
005     *  You may not use this file except in compliance with the License. You
006     *  may obtain a copy of the License at
007     *
008     *      http://www.opensource.org/licenses/eclipse-1.0.php
009     *
010     *  See the COPYRIGHT.txt file distributed with this work for information
011     *  regarding copyright ownership.
012     */
013    package org.jikesrvm.compilers.opt.util;
014    
015    import java.util.Enumeration;
016    import java.util.NoSuchElementException;
017    
018    /**
019     * Enumeration that doesn't have any elements.
020     * Use the EMPTY object to access.
021     */
022    public final class EmptyEnumerator implements Enumeration<Object> {
023      private static final EmptyEnumerator EMPTY = new EmptyEnumerator();
024    
025      @SuppressWarnings({"unchecked", "RedundantCast"})
026      public static <T> Enumeration<T> emptyEnumeration() {
027        return (Enumeration<T>) (Enumeration) EMPTY;
028      }
029    
030      public boolean hasMoreElements() {
031        return false;
032      }
033    
034      public Object nextElement() {
035        throw new NoSuchElementException();
036      }
037    
038      private EmptyEnumerator() {
039      }
040    }
041    
042    
043