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Java > Open Source Codes > org > apache > commons > collections > collection > UnmodifiableCollection


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 JavaDoc;
19 import java.util.Iterator JavaDoc;
20
21 import org.apache.commons.collections.Unmodifiable;
22 import org.apache.commons.collections.iterators.UnmodifiableIterator;
23
24 /**
25  * Decorates another <code>Collection</code> to ensure it can't be altered.
26  * <p>
27  * This class is Serializable from Commons Collections 3.1.
28  *
29  * @since Commons Collections 3.0
30  * @version $Revision: 1.8 $ $Date: 2004/06/03 22:02:13 $
31  *
32  * @author Stephen Colebourne
33  */
34 public final class UnmodifiableCollection
35         extends AbstractSerializableCollectionDecorator
36         implements Unmodifiable {
37
38     /** Serialization version */
39     private static final long serialVersionUID = -239892006883819945L;
40
41     /**
42      * Factory method to create an unmodifiable collection.
43      * <p>
44      * If the collection passed in is already unmodifiable, it is returned.
45      *
46      * @param coll the collection to decorate, must not be null
47      * @return an unmodifiable collection
48      * @throws IllegalArgumentException if collection is null
49      */
50     public static Collection JavaDoc decorate(Collection JavaDoc coll) {
51         if (coll instanceof Unmodifiable) {
52             return coll;
53         }
54         return new UnmodifiableCollection(coll);
55     }
56     
57     //-----------------------------------------------------------------------
58 /**
59      * Constructor that wraps (not copies).
60      *
61      * @param coll the collection to decorate, must not be null
62      * @throws IllegalArgumentException if collection is null
63      */
64     private UnmodifiableCollection(Collection JavaDoc coll) {
65         super(coll);
66     }
67
68     //-----------------------------------------------------------------------
69 public Iterator JavaDoc iterator() {
70         return UnmodifiableIterator.decorate(getCollection().iterator());
71     }
72
73     public boolean add(Object JavaDoc object) {
74         throw new UnsupportedOperationException JavaDoc();
75     }
76
77     public boolean addAll(Collection JavaDoc coll) {
78         throw new UnsupportedOperationException JavaDoc();
79     }
80
81     public void clear() {
82         throw new UnsupportedOperationException JavaDoc();
83     }
84
85     public boolean remove(Object JavaDoc object) {
86         throw new UnsupportedOperationException JavaDoc();
87     }
88
89     public boolean removeAll(Collection JavaDoc coll) {
90         throw new UnsupportedOperationException JavaDoc();
91     }
92
93     public boolean retainAll(Collection JavaDoc coll) {
94         throw new UnsupportedOperationException JavaDoc();
95     }
96
97 }
98
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