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1   package org.apache.torque.util;
2   
3   /*
4    * Copyright 2001-2005 The Apache Software Foundation.
5    *
6    * Licensed under the Apache License, Version 2.0 (the "License")
7    * you may not use this file except in compliance with the License.
8    * You may obtain a copy of the License at
9    *
10   *     http://www.apache.org/licenses/LICENSE-2.0
11   *
12   * Unless required by applicable law or agreed to in writing, software
13   * distributed under the License is distributed on an "AS IS" BASIS,
14   * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
15   * See the License for the specific language governing permissions and
16   * limitations under the License.
17   */
18  
19  import java.util.ArrayList;
20  
21  /***
22   * List with unique entries. UniqueList does not allow null nor duplicates.
23   *
24   * @author <a href="mailto:mpoeschl@marmot.at">Martin Poeschl</a>
25   * @version $Id: UniqueList.java 239630 2005-08-24 12:25:32Z henning $
26   */
27  public class UniqueList extends ArrayList
28  {
29      /***
30       * Adds an Object to the list.
31       *
32       * @param o the Object to add
33       * @return true if the Object is added
34       */
35      public boolean add(Object o)
36      {
37          if (o != null && !contains(o))
38          {
39              return super.add(o);
40          }
41          return false;
42      }
43  }