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 

    35 import java.util.EnumSet;

    36 import java.util.Iterator;

    37 import java.util.Set;

    38 

    39 public 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 }