Generics make a class, interface and, method, consider all (reference) types that are given dynamically as parameters. 

This ensures type safety.

 Generic class parameters are specified in angle brackets “<>” after the class name as of the instance variable.

Generic constructors are the same as generic methods.

 For generic constructors after the public keyword and before the class name the type parameter must be placed.

 Constructors can be invoked with any type of a parameter after defining a generic constructor. 

A constructor is a block of code that initializes the newly created object. 

It is an instance method with no return type. 

The name of the constructor is same as the class name. Constructors can be Generic, despite its class is not Generic. 

https://www.geeksforgeeks.org/generic-constructors-and-interfaces-in-java/