View Javadoc

    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.log4j.helpers;
    18
    19  import java.util.Enumeration;
    20  import java.util.NoSuchElementException;
    21
    22  /**
    23   * An always-empty Enumerator.
    24   *
    25   * @since version 1.0
    26   */
    27  @SuppressWarnings("rawtypes")
    28  public final class NullEnumeration implements Enumeration {
    29      private static final NullEnumeration INSTANCE = new NullEnumeration();
    30
    31      private NullEnumeration() {
    32      }
    33
    34      public static NullEnumeration getInstance() {
    35          return INSTANCE;
    36      }
    37
    38      @Override
    39      public boolean hasMoreElements() {
    40          return false;
    41      }
    42
    43      @Override
    44      public Object nextElement() {
    45          throw new NoSuchElementException();
    46      }
    47  }