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Java > Open Source Codes > org > apache > commons > collections > Unmodifiable


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;
17
18 /**
19  * Marker interface for collections, maps and iterators that are unmodifiable.
20  * <p>
21  * This interface enables testing such as:
22  * <pre>
23  * if (coll instanceof Unmodifiable) {
24  * coll = new ArrayList(coll);
25  * }
26  * // now we know coll is modifiable
27  * </pre>
28  * Of course all this only works if you use the Unmodifiable classes defined
29  * in this library. If you use the JDK unmodifiable class via java util Collections
30  * then the interface won't be there.
31  *
32  * @since Commons Collections 3.0
33  * @version $Revision: 1.4 $ $Date: 2004/02/18 01:15:42 $
34  *
35  * @author Stephen Colebourne
36  */
37 public interface Unmodifiable {
38     // marker interface - no methods to implement
39 }
40
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