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 LargeEnumIteratorRemoveResilience {

    40     // enum with more than 64 values

    41     private static enum LargeEnum {

    42         e00, e01, e02, e03, e04, e05, e06, e07,

    43         e08, e09, e0A, e0B, e0C, e0D, e0E, e0F,

    44         e10, e11, e12, e13, e14, e15, e16, e17,

    45         e18, e19, e1A, e1B, e1C, e1D, e1E, e1F,

    46         e20, e21, e22, e23, e24, e25, e26, e27,

    47         e28, e29, e2A, e2B, e2C, e2D, e2E, e2F,

    48         e30, e31, e32, e33, e34, e35, e36, e37,

    49         e38, e39, e3A, e3B, e3C, e3D, e3E, e3F,

    50         e40, e41, e42, e43, e44, e45, e46, e47,

    51         e48, e49, e4A, e4B, e4C, e4D, e4E, e4F,

    52     }

    53 

    54     public static void main(final String[] args) throws Exception {

    55         final Set<LargeEnum> set = EnumSet.noneOf(LargeEnum.class);

    56 

    57         set.add(LargeEnum.e2D);

    58         set.add(LargeEnum.e42);

    59 

    60         final Iterator<LargeEnum> iterator = set.iterator();

    61 

    62         int size = set.size();

    63         LargeEnum element = iterator.next();

    64 

    65         iterator.remove();

    66         checkSetAfterRemoval(set, size, element);

    67 

    68         size = set.size();

    69         element = iterator.next();

    70 

    71         set.remove(element);

    72         checkSetAfterRemoval(set, size, element);

    73 

    74         // The Java API declares that the behaviour here - to call

    75         // iterator.remove() after the underlying collection has been

    76         // modified - is "unspecified".

    77         // However, in the case of iterators for EnumSet, it is easy to

    78         // implement their remove() operation such that the set is

    79         // unmodified if it is called for an element that has already been

    80         // removed from the set - this being the naturally "resilient"

    81         // behaviour.

    82         iterator.remove();

    83         checkSetAfterRemoval(set, size, element);

    84     }

    85 

    86     private static void checkSetAfterRemoval(final Set<LargeEnum> set,

    87             final int origSize, final LargeEnum removedElement)

    88             throws Exception {

    89         if (set.size() != (origSize - 1)) {

    90             throw new Exception("Test FAILED: Unexpected set size after removal; expected '" + (origSize - 1) + "' but found '" + set.size() + "'");

    91         }

    92         if (set.contains(removedElement)) {

    93             throw new Exception("Test FAILED: Element returned from iterator unexpectedly still in set after removal.");

    94         }

    95     }

    96 }