1/*
2 * Copyright (c) 2006, Oracle and/or its affiliates. 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 Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
20 * or visit www.oracle.com if you need additional information or have any
21 * questions.
22 */
23
24/*
25 * @test
26 * @bug     6387919
27 * @summary Confirm ThreadLocal.set() usage is not a side effect of get()
28 * @author  Pete Soper
29 */
30public class ImmutableLocal
31{
32    /**
33     * {@link ThreadLocal} guaranteed to always return the same reference.
34     */
35    public abstract static class ImmutableThreadLocal extends ThreadLocal {
36        public void set(final Object value) {
37            throw new RuntimeException("ImmutableThreadLocal set called");
38        }
39
40        // force override
41        protected abstract Object initialValue();
42    }
43
44    private static final ThreadLocal cache = new ImmutableThreadLocal() {
45        public Object initialValue() {
46            return Thread.currentThread().getName();
47        }
48    };
49
50    public static void main(final String[] args) {
51        System.out.println("cache.get() = " + cache.get());
52    }
53}
54