1/*
2 * Copyright (c) 2011, 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 * Portions Copyright (c) 2011 IBM Corporation
26 */
27
28/*
29 * @test
30 * @bug 7014637
31 * @summary EnumSet's iterator.remove() can be resilient to set's modification.
32 * @author Neil Richards <neil.richards@ngmr.net>, <neil_richards@uk.ibm.com>
33 */
34
35import java.util.EnumSet;
36import java.util.Iterator;
37import java.util.Set;
38
39public class SmallEnumIteratorRemoveResilience {
40    // enum with less than 64 values
41    private static enum SmallEnum { e0, e1, e2 }
42
43    public static void main(final String[] args) throws Exception {
44        final Set<SmallEnum> set = EnumSet.noneOf(SmallEnum.class);
45
46        set.add(SmallEnum.e0);
47        set.add(SmallEnum.e1);
48
49        final Iterator<SmallEnum> iterator = set.iterator();
50
51        int size = set.size();
52        SmallEnum element = iterator.next();
53
54        iterator.remove();
55        checkSetAfterRemoval(set, size, element);
56
57        size = set.size();
58        element = iterator.next();
59
60        set.remove(element);
61        checkSetAfterRemoval(set, size, element);
62
63        // The Java API declares that the behaviour here - to call
64        // iterator.remove() after the underlying collection has been
65        // modified - is "unspecified".
66        // However, in the case of iterators for EnumSet, it is easy to
67        // implement their remove() operation such that the set is
68        // unmodified if it is called for an element that has already been
69        // removed from the set - this being the naturally "resilient"
70        // behaviour.
71        iterator.remove();
72        checkSetAfterRemoval(set, size, element);
73    }
74
75    private static void checkSetAfterRemoval(final Set<SmallEnum> set,
76            final int origSize, final SmallEnum removedElement)
77            throws Exception {
78        if (set.size() != (origSize - 1)) {
79            throw new Exception("Test FAILED: Unexpected set size after removal; expected '" + (origSize - 1) + "' but found '" + set.size() + "'");
80        }
81        if (set.contains(removedElement)) {
82            throw new Exception("Test FAILED: Element returned from iterator unexpectedly still in set after removal.");
83        }
84    }
85}
86