A hash table is a data structure that allows you to map a key to a value. Internally, it usually uses an array to store the elements and a hash function to calculate the position of the element in the array, using its key. The main advantage of this data structure is that the insert, delete, and search operations are very fast here, so it's very useful in situations when you have to carry out a lot of search operations.
The Java API provides different hash table implementations through the Map and ConcurrentMap interfaces. The ConcurrentMap interface provides thread-safety and atomic guarantees to all the operations, so you can use them in concurrent applications. The ConcurrentHashMap class implements the ConcurrentMap ...
