util/Collections/EmptyCollectionSerialization.java

/*
 * Copyright 2002 Sun Microsystems, Inc.  All Rights Reserved.
 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
 *
 * This code is free software; you can redistribute it and/or modify it
 * under the terms of the GNU General Public License version 2 only, as
 * published by the Free Software Foundation.
 *
 * This code is distributed in the hope that it will be useful, but WITHOUT
 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
 * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
 * version 2 for more details (a copy is included in the LICENSE file that
 * accompanied this code).
 *
 * You should have received a copy of the GNU General Public License version
 * 2 along with this work; if not, write to the Free Software Foundation,
 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
 *
 * Please contact Sun Microsystems, Inc., 4150 Network Circle, Santa Clara,
 * CA 95054 USA or visit www.sun.com if you need additional information or
 * have any questions.
 */

/*
 * @test
 * @bug     4684279
 * @summary Empty utility collections should be singletons
 * @author  Josh Bloch
 */

import java.util.*;
import java.io.*;

public class EmptyCollectionSerialization {
    private static Object patheticDeepCopy(Object o) throws Exception {
        // Serialize
        ByteArrayOutputStream bos = new ByteArrayOutputStream();
        ObjectOutputStream oos = new ObjectOutputStream(bos);
        oos.writeObject(o);
        byte[] serializedForm = bos.toByteArray();

        // Deserialize
        InputStream is = new ByteArrayInputStream(serializedForm);
        ObjectInputStream ois = new ObjectInputStream(is);
        return ois.readObject();
    }

    private static boolean isSingleton(Object o) throws Exception {
        return patheticDeepCopy(o) == o;
    }

    public static void main(String[] args) throws Exception {
        if (!isSingleton(Collections.EMPTY_SET))
            throw new Exception("EMPTY_SET");
        if (!isSingleton(Collections.EMPTY_LIST))
            throw new Exception("EMPTY_LIST");
        if (!isSingleton(Collections.EMPTY_MAP))
            throw new Exception("EMPTY_MAP");
    }
}
Revision:	1.1
Committed:	Tue Sep 1 01:24:16 2009 UTC (14 years, 8 months ago) by jsr166
Branch:	MAIN
Log Message:	import tests from openjdk
#	Content
1	/*
2	* Copyright 2002 Sun Microsystems, Inc. All Rights Reserved.
3	* DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
4	*
5	* This code is free software; you can redistribute it and/or modify it
6	* under the terms of the GNU General Public License version 2 only, as
7	* published by the Free Software Foundation.
8	*
9	* This code is distributed in the hope that it will be useful, but WITHOUT
10	* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
11	* FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
12	* version 2 for more details (a copy is included in the LICENSE file that
13	* accompanied this code).
14	*
15	* You should have received a copy of the GNU General Public License version
16	* 2 along with this work; if not, write to the Free Software Foundation,
17	* Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
18	*
19	* Please contact Sun Microsystems, Inc., 4150 Network Circle, Santa Clara,
20	* CA 95054 USA or visit www.sun.com if you need additional information or
21	* have any questions.
22	*/
23
24	/*
25	* @test
26	* @bug 4684279
27	* @summary Empty utility collections should be singletons
28	* @author Josh Bloch
29	*/
30
31	import java.util.*;
32	import java.io.*;
33
34	public class EmptyCollectionSerialization {
35	private static Object patheticDeepCopy(Object o) throws Exception {
36	// Serialize
37	ByteArrayOutputStream bos = new ByteArrayOutputStream();
38	ObjectOutputStream oos = new ObjectOutputStream(bos);
39	oos.writeObject(o);
40	byte[] serializedForm = bos.toByteArray();
41
42	// Deserialize
43	InputStream is = new ByteArrayInputStream(serializedForm);
44	ObjectInputStream ois = new ObjectInputStream(is);
45	return ois.readObject();
46	}
47
48	private static boolean isSingleton(Object o) throws Exception {
49	return patheticDeepCopy(o) == o;
50	}
51
52	public static void main(String[] args) throws Exception {
53	if (!isSingleton(Collections.EMPTY_SET))
54	throw new Exception("EMPTY_SET");
55	if (!isSingleton(Collections.EMPTY_LIST))
56	throw new Exception("EMPTY_LIST");
57	if (!isSingleton(Collections.EMPTY_MAP))
58	throw new Exception("EMPTY_MAP");
59	}
60	}