Java HashMap<K,V> is a class that implements the Java Map<K,V> interface using a hash table to store key-value pairs. It allows efficient lookups, insertions, and deletions based on keys and is part of the Java Collections Framework. Introduced in Java 1995 with Java 1.2, HashMap is widely used in Java applications for implementing associative arrays or dictionaries, where fast access to data via keys is essential.

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