On 05/05/2015 05:12 AM, Paul Sandoz wrote:
On May 5, 2015, at 7:54 AM, Martin Buchholz <[email protected]> wrote:One query in ConcurrentSkipListMap, we have: 2500 // else use iterator 2501 @SuppressWarnings("unchecked") Iterator<Map.Entry<Object,E>> it = 2502 ((SubMap<Object,E>)m).entryIterator(); and then 2578 // else use iterator 2579 Iterator<Map.Entry<K1,V1>> it = ((SubMap<K1,V1>)m).entryIterator(); why does only the former require the "unchecked" warning suppression? Good question.Yes, for values the key type parameter is "thrown" away and reconstituting as Object is not type safe.
It was originally done this way because keeping the "K" parameter hit a generics type parameter inference limitation. Similarly for some constructions in TreeMap. But I think jdk8 (not just 9) allow this to be done with explicit type parameters, so now is as good a time to update this as any, combining both Martin's and Paul's changes. Someone might also want to look at TreeMap. -Doug
