The improvement of hashmap applies only to high collision nodes that also implement comparable. It's a very special case. java.util.TreeMap has always been a re

The improvement of hashmap applies only to high collision nodes that also implement comparable. It's a very special case. java.util.TreeMap has always been a red/black one. On a flip note: HashMap in Java is sort of jack of trades, it's node based which means it has poor memory/caching characteristics - around 36bytes per standard node (compared to ~10 for array backed one) - and Nodes+array tend to be top3 objects in heap dumps. The iteration is sort of 'random' (unlikely LinkedHashMap) which has been a source of lots of issues not manifesting during testing. However, it doesn't degrade in virtually any use case. Normally, I don't use it - either a custom one (CompactHashMap), LinkedHashMap (being the go to hashtable), or ConcurrentHahshMap.