Set - HashSet does not allow duplicates
There was a reason for the creation of the Set interface; it was designed not to allow duplicate elements. A duplicate is identified using the equals() method, implemented in the class whose objects are elements of the set.
Preferring variable type Set
As in the case of List, using type Set for the variable that holds a reference to the object of the class that implements the Set interface is a good programming practice called coding to an interface. It assures independence of the client code from any particular implementation. So, it is a good habit to write Set<Person> persons = new HashSet<>(), for example.
Why is it called HashSet?
In programming, a hash value is a 32-bit signed integer that represents some data. It is used in such data structures as a HashTable. After a record is created in a HashTable, its hash value can be used later to quickly find and retrieve the stored data. A hash value is also called a hash code, digest, or simply...
