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    1   /*
    2    * Licensed to the Apache Software Foundation (ASF) under one or more
    3    * contributor license agreements.  See the NOTICE file distributed with
    4    * this work for additional information regarding copyright ownership.
    5    * The ASF licenses this file to You under the Apache License, Version 2.0
    6    * (the "License"); you may not use this file except in compliance with
    7    * the License.  You may obtain a copy of the License at
    8    *
    9    *      http://www.apache.org/licenses/LICENSE-2.0
    10   *
    11   * Unless required by applicable law or agreed to in writing, software
    12   * distributed under the License is distributed on an "AS IS" BASIS,
    13   * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
    14   * See the License for the specific language governing permissions and
    15   * limitations under the License.
    16   */
    17  package org.apache.portals.bridges.jsf;
    18
    19  import java.util.Enumeration;
    20
    21  /***
    22   * <p>
    23   * Enumeration without elements
    24   * </p>
    25   * <p>
    26   * Code provided by MyFaces project.
    27   * </p>
    28   *
    29   * @author <a href="dlestrat@apache.org">David Le Strat </a>
    30   */
    31  public final class NullEnumeration implements Enumeration
    32  {
    33      /*** Null enumeration. */
    34      private static final NullEnumeration nullEnumeration = new NullEnumeration();
    35
    36      /***
    37       * @return An instance of the enumeration.
    38       */
    39      public static final NullEnumeration instance()
    40      {
    41          return nullEnumeration;
    42      }
    43
    44      /***
    45       * @see java.util.Enumeration#hasMoreElements()
    46       */
    47      public boolean hasMoreElements()
    48      {
    49          return false;
    50      }
    51
    52      /***
    53       * @see java.util.Enumeration#nextElement()
    54       */
    55      public Object nextElement()
    56      {
    57          throw new UnsupportedOperationException("NullEnumeration has no elements");
    58      }
    59  }