001/*
002 * Licensed to the Apache Software Foundation (ASF) under one or more
003 * contributor license agreements.  See the NOTICE file distributed with
004 * this work for additional information regarding copyright ownership.
005 * The ASF licenses this file to You under the Apache License, Version 2.0
006 * (the "License"); you may not use this file except in compliance with
007 * the License.  You may obtain a copy of the License at
008 *
009 *     http://www.apache.org/licenses/LICENSE-2.0
010 *
011 * Unless required by applicable law or agreed to in writing, software
012 * distributed under the License is distributed on an "AS IS" BASIS,
013 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
014 * See the License for the specific language governing permissions and
015 * limitations under the License.
016 */
017package org.apache.commons.el;
018
019/**
020 *
021 * <p>An expression representing a null literal value
022 * 
023 * @author Nathan Abramson - Art Technology Group
024 * @version $Change: 181177 $$DateTime: 2001/06/26 08:45:09 $$Author: bayard $
025 **/
026
027public class NullLiteral
028  extends Literal
029{
030  //-------------------------------------
031  // Member variables
032  //-------------------------------------
033
034  public static final NullLiteral SINGLETON = new NullLiteral ();
035
036  //-------------------------------------
037  /**
038   *
039   * Constructor
040   **/
041  public NullLiteral ()
042  {
043    super (null);
044  }
045
046  //-------------------------------------
047  // Expression methods
048  //-------------------------------------
049  /**
050   *
051   * Returns the expression in the expression language syntax
052   **/
053  public String getExpressionString ()
054  {
055    return "null";
056  }
057
058  //-------------------------------------
059}