code: /*
   * Licensed to the Apache Software Foundation (ASF) under one or more
   * contributor license agreements.  See the NOTICE file distributed with
   * this work for additional information regarding copyright ownership.
   * The ASF licenses this file to You under the Apache License, Version 2.0
   * (the "License"); you may not use this file except in compliance with
   * the License.  You may obtain a copy of the License at
   * 
   *      http://www.apache.org/licenses/LICENSE-2.0
   * 
   * Unless required by applicable law or agreed to in writing, software
   * distributed under the License is distributed on an "AS IS" BASIS,
   * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
   * See the License for the specific language governing permissions and
   * limitations under the License.
   */
  package org.apache.commons.lang;
  
  /**
   * <p>Thrown to indicate that an argument was <code>null</code> and should
   * not have been.
   * This exception supplements the standard <code>IllegalArgumentException</code>
   * by providing a more semantically rich description of the problem.</p>
   * 
   * <p><code>NullArgumentException</code> represents the case where a method takes
   * in a parameter that must not be <code>null</code>.
   * Some coding standards would use <code>NullPointerException</code> for this case,
   * others will use <code>IllegalArgumentException</code>.
   * Thus this exception would be used in place of
   * <code>IllegalArgumentException</code>, yet it still extends it.</p>
   * 
   * <pre>
   * public void foo(String str) {
   *   if (str == null) {
   *     throw new NullArgumentException("str");
   *   }
   *   // do something with the string
   * }
   * </pre>
   * 
   * @author Matthew Hawthorne
   * @author Stephen Colebourne
   * @since 2.0
   * @version $Id: NullArgumentException.java 437554 2006-08-28 06:21:41Z bayard $
   */
  public class NullArgumentException extends IllegalArgumentException {
  
      /**
       * Required for serialization support.
       * 
       * @see java.io.Serializable
       */
      private static final long serialVersionUID = 1174360235354917591L;
  
      /**
       * <p>Instantiates with the given argument name.</p>
       *
       * @param argName  the name of the argument that was <code>null</code>.
       */
      public NullArgumentException(String argName) {
          super((argName == null ? "Argument" : argName) + " must not be null.");
      }
  
  }
  