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     */
017    package 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    
027    public 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    }