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