Java HashMap.computeIfPresent() is a method in the Java HashMap class that updates the value associated with a specified key if the key is already present in the map. It uses a remapping function to compute the new value. Introduced in Java 2014 with Java 8, computeIfPresent() is commonly used to modify existing values in a map based on some computation, such as in caching or value transformation scenarios.

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