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https://issues.apache.org/jira/browse/COLLECTIONS-889?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=18088574#comment-18088574
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Gary D. Gregory commented on COLLECTIONS-889:
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Hello [~rickydong]
Issues with PRs get a higher priority in my queue ;)
> `IndexedCollection.remove()` clears the whole key bucket in non-unique indexes
> ------------------------------------------------------------------------------
>
> Key: COLLECTIONS-889
> URL: https://issues.apache.org/jira/browse/COLLECTIONS-889
> Project: Commons Collections
> Issue Type: Bug
> Components: Collection
> Reporter: Ruiqi Dong
> Priority: Major
>
> *Summary*
> For non-unique indexes, multiple collection elements may share the same
> transformed key. The current `remove(...)` implementation removes the object
> from the decorated collection correctly, but then removes the entire key from
> the index. That drops the remaining same-key elements from the index even
> though they are still present in the collection.
>
> *Affected code*
> File:
> `src/main/java/org/apache/commons/collections4/collection/IndexedCollection.java`
> {code:java}
> @SuppressWarnings("unchecked")
> @Override
> public boolean remove(final Object object) {
> final boolean removed = super.remove(object);
> if (removed) {
> removeFromIndex((C) object);
> }
> return removed;
> }
> private void removeFromIndex(final C object) {
> index.remove(keyTransformer.apply(object));
> } {code}
> *Reproducer*
> Add the following test to
> `src/test/java/org/apache/commons/collections4/collection/IndexedCollectionTest.java`
> {code:java}
> @Test
> void testRemovePreservesRemainingValuesWithSameTransformedKey() {
> final IndexedCollection<Integer, String> indexed =
> (IndexedCollection<Integer, String>) decorateCollection(new
> ArrayList<>());
> indexed.add("01");
> indexed.add("1");
> indexed.remove("01");
> assertEquals("1", indexed.get(1));
> assertNotNull(indexed.values(1));
> assertEquals(asList("1"), new ArrayList<>(indexed.values(1)));
> } {code}
> Run:
> {code:java}
> mvn -q
> -Dtest=org.apache.commons.collections4.collection.IndexedCollectionTest#testRemovePreservesRemainingValuesWithSameTransformedKey
> test {code}
> Observed behavior:
> `get(1)` returns `null` even though `"1"` is still present in the decorated
> collection.
> {code:java}
> expected: <1> but was: <null> {code}
> Expected behavior:
> Removing `"01"` should leave the other same-key value `"1"` indexed and
> retrievable.
>
> In the non-unique configuration, the index is supposed to track all values
> that share a key. Removing one value should only remove that single value
> from the index entry, not delete the whole key bucket. The current
> implementation leaves the collection and the index out of sync after a normal
> successful `remove(...)`.
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