Java ConcurrentHashMap.containsKey() is a method in the Java ConcurrentHashMap class that checks whether a specific key is present in the map. It is designed to be thread-safe, allowing multiple threads to concurrently query the map without risk of data inconsistency. Introduced in Java 2004 with Java 5, containsKey() is widely used in concurrent programming to check for key existence without blocking other threads.

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