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1   //----------------------------------------------------------------------
2   // 
3   // PerfectJPattern: "Design patterns are good but components are better!" 
4   // NullRequest.java Copyright (c) 2009 Giovanni Azua Garcia
5   // bravegag@hotmail.com
6   //  
7   // This program is free software; you can redistribute it and/or
8   // modify it under the terms of the GNU General Public License
9   // as published by the Free Software Foundation; either version 3
10  // of the License, or (at your option) any later version.
11  //
12  // This program is distributed in the hope that it will be useful,
13  // but WITHOUT ANY WARRANTY; without even the implied warranty of
14  // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
15  // GNU General Public License for more details.
16  //
17  // You should have received a copy of the GNU General Public License
18  // along with this program; if not, see <http://www.gnu.org/licenses/>.
19  //
20  //----------------------------------------------------------------------
21  package org.perfectjpattern.core.api.behavioral.chainofresponsibility;
22  
23  import org.perfectjpattern.core.api.creational.singleton.ISingleton;
24  
25  /**
26   * Null Object Pattern implementation of Chain of Responsibility 
27   * Request Parameter. 
28   * <br/><br/>
29   * <code>NullRequest</code> is a Singleton therefore it may not be directly 
30   * instantiated, neither it may be extended.
31   * 
32   * @author <a href="mailto:bravegag@hotmail.com">Giovanni Azua</a>
33   * @version $Revision: 1.0 $ $Date: Nov 6, 2007 5:35:36 PM $
34   */
35  public final
36  class NullRequest
37  implements ISingleton
38  {
39      //------------------------------------------------------------------------
40      // public
41      //------------------------------------------------------------------------
42      /**
43       * Returns Singleton instance of <code>NullRequest</code>.
44       * 
45       * @return Singleton instance of <code>NullRequest</code>.
46       */
47      public static NullRequest
48      getInstance()
49      {
50          return INSTANCE;
51      }    
52      
53      //------------------------------------------------------------------------
54      // private
55      //------------------------------------------------------------------------
56      private 
57      NullRequest()
58      {       
59          // do nothing
60      }
61      
62      //------------------------------------------------------------------------
63      // members
64      //------------------------------------------------------------------------
65      /**
66       * Singleton instance of <code>NullRequest</code>
67       */
68      private static final NullRequest INSTANCE = new NullRequest();    
69  }