Java AbstractMap.entrySet() is a method in the Java AbstractMap class that returns a set view of the key-value pairs contained in the map. It allows you to iterate over both the keys and values of the map simultaneously. Introduced in Java 1995 with Java 1.2, entrySet() is essential for performing operations that involve both the keys and values, such as iterating through a map to process or modify its contents.

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