[ https://issues.apache.org/jira/browse/COLLECTIONS-310?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13580821#comment-13580821 ]
Thomas Vahrst commented on COLLECTIONS-310: ------------------------------------------- SetUniqueList.patch contains JUnit Tests and Variant No. 1 for SetUniqueList. I am not sure whether the patch has a correct format (I am not able to re-apply the patch in Netbeans...) so I attached the corresponding java files as well. > Modifications of a SetUniqueList.subList() invalidate the parent list > --------------------------------------------------------------------- > > Key: COLLECTIONS-310 > URL: https://issues.apache.org/jira/browse/COLLECTIONS-310 > Project: Commons Collections > Issue Type: Bug > Components: List > Affects Versions: 3.2, Nightly Builds > Reporter: Christian Semrau > Priority: Minor > Fix For: 4.0 > > Attachments: SetUniqueList.java, SetUniqueList.patch, > SetUniqueListTest.java > > > The List returned by SetUniqueList.subList() is again a SetUniqueList. The > contract for List.subList() says that the returned list supports all the > operations of the parent list, and it is backed by the parent list. > We have a SetUniqueList uniqueList equal to {"Hello", "World"}. We get a > subList containing the last element. Now we add the element "Hello", > contained in the uniqueList but not in the subList, to the subList. > What should happen? > Should the subList behave like a SetUniqueList and add the element - meaning > that it changes position in the uniqueList because at the old place it gets > removed, so now uniqueList equals {"World", "Hello"} (which fails)? > Or should the element not be added, because it is already contained in the > parent list, thereby violating the SetUniqueList-ness of the subList (which > fails)? > I prefer the former behaviour, because modifications should only be made > through the subList and not through the parent list (as explained in > List.subList()). > What should happen if we replace (using set) the subList element "World" with > "Hello" instead of adding an element? > The subList should contain only "Hello", and for the parent list, the old > element 0 (now a duplicate of the just set element 1) should be removed > (which fails). > And of course the parent list should know what happens to it (specifically, > its uniqueness Set) (which fails in the current snapshot). > public void testSubListAddNew() { > List uniqueList = SetUniqueList.decorate(new ArrayList()); > uniqueList.add("Hello"); > uniqueList.add("World"); > List subList = uniqueList.subList(1, 2); > subList.add("Goodbye"); > List expectedSubList = Arrays.asList(new Object[] { "World", > "Goodbye" }); > List expectedParentList = Arrays.asList(new Object[] { "Hello", > "World", "Goodbye" }); > assertEquals(expectedSubList, subList); > assertEquals(expectedParentList, uniqueList); > assertTrue(uniqueList.contains("Goodbye")); // fails > } > public void testSubListAddDuplicate() { > List uniqueList = SetUniqueList.decorate(new ArrayList()); > uniqueList.add("Hello"); > uniqueList.add("World"); > List subList = uniqueList.subList(1, 2); > subList.add("Hello"); > List expectedSubList = Arrays.asList(new Object[] { "World", > "Hello" }); > List expectedParentList = Arrays.asList(new Object[] { "World", > "Hello" }); > assertEquals(expectedSubList, subList); > assertEquals(expectedParentList, uniqueList); // fails > } > public void testSubListSetDuplicate() { > List uniqueList = SetUniqueList.decorate(new ArrayList()); > uniqueList.add("Hello"); > uniqueList.add("World"); > List subList = uniqueList.subList(1, 2); > subList.set(0, "Hello"); > List expectedSubList = Arrays.asList(new Object[] { "Hello" }); > List expectedParentList = Arrays.asList(new Object[] { "Hello" > }); > assertEquals(expectedSubList, subList); > assertEquals(expectedParentList, uniqueList); // fails > } -- This message is automatically generated by JIRA. If you think it was sent incorrectly, please contact your JIRA administrators For more information on JIRA, see: http://www.atlassian.com/software/jira