TypedSet


1   /*
2    *  Copyright 2003-2004 The Apache Software Foundation
3    *
4    *  Licensed under the Apache License, Version 2.0 (the "License");
5    *  you may not use this file except in compliance with the License.
6    *  You may obtain a copy of the License at
7    *
8    *      http://www.apache.org/licenses/LICENSE-2.0
9    *
10   *  Unless required by applicable law or agreed to in writing, software
11   *  distributed under the License is distributed on an "AS IS" BASIS,
12   *  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
13   *  See the License for the specific language governing permissions and
14   *  limitations under the License.
15   */
16  package org.apache.commons.collections.set;
17  
18  import java.util.Set  ;
19  
20  import org.apache.commons.collections.functors.InstanceofPredicate;
21  
22  /**
23   * Decorates another <code>Set</code> to validate that elements
24   * added are of a specific type.
25   * <p>
26   * The validation of additions is performed via an instanceof test against 
27   * a specified <code>Class</code>. If an object cannot be added to the
28   * collection, an IllegalArgumentException is thrown.
29   *
30   * @since Commons Collections 3.0
31   * @version $Revision: 1.4 $ $Date: 2004/05/07 23:28:38 $
32   * 
33   * @author Stephen Colebourne
34   * @author Matthew Hawthorne
35   */
36  public class TypedSet {
37  
38      /**
39       * Factory method to create a typed set.
40       * <p>
41       * If there are any elements already in the set being decorated, they
42       * are validated.
43       * 
44       * @param set  the set to decorate, must not be null
45       * @param type  the type to allow into the collection, must not be null
46       * @throws IllegalArgumentException if set or type is null
47       * @throws IllegalArgumentException if the set contains invalid elements
48       */
49      public static Set   decorate(Set   set, Class   type) {
50          return new PredicatedSet(set, InstanceofPredicate.getInstance(type));
51      }
52      
53      /**
54       * Restrictive constructor.
55       */
56      protected TypedSet() {
57      }
58  
59  }
60
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