Java ConcurrentSkipListMap.lastKey() is a method in the Java ConcurrentSkipListMap class that retrieves the highest key currently present in the map. It is thread-safe, ensuring that the operation remains consistent even in concurrent environments. Introduced in Java 2004 with Java 5, lastKey() is useful for applications requiring ordered data where access to the largest key is necessary.

https://docs.oracle.com/javase/8/docs/api/java/util/concurrent/ConcurrentSkipListMap.html