/*
* Copyright (c) 2002, Oracle and/or its affiliates. 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 Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
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*/
/*
* @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");
}
}