TypedCollection


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.collection;
17  
18  import java.util.Collection  ;
19  
20  import org.apache.commons.collections.functors.InstanceofPredicate;
21  
22  /**
23   * Decorates a <code>Collection</code> to validate that elements added are of a specific type.
24   * <p>
25   * The validation of additions is performed via an instanceof test against 
26   * a specified <code>Class</code>. If an object cannot be added to the
27   * collection, an IllegalArgumentException is thrown.
28   *
29   * @since Commons Collections 3.0
30   * @version $Revision: 1.5 $ $Date: 2004/05/15 12:39:13 $
31   * 
32   * @author Stephen Colebourne
33   * @author Matthew Hawthorne
34   */
35  public class TypedCollection {
36  
37      /**
38       * Factory method to create a typed collection.
39       * <p>
40       * If there are any elements already in the collection being decorated, they
41       * are validated.
42       * 
43       * @param coll  the collection to decorate, must not be null
44       * @param type  the type to allow into the collection, must not be null
45       * @return a new typed collection
46       * @throws IllegalArgumentException if collection or type is null
47       * @throws IllegalArgumentException if the collection contains invalid elements
48       */
49      public static Collection   decorate(Collection   coll, Class   type) {
50          return new PredicatedCollection(coll, InstanceofPredicate.getInstance(type));
51      }
52      
53      /**
54       * Restrictive constructor.
55       */
56      protected TypedCollection() {
57          super();
58      }
59  
60  }
61
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