Cannot instantiate the type List<Product>

List is an interface. Interfaces cannot be instantiated. Only concrete types can be instantiated. You probably want to use an ArrayList, which is an implementation of the List interface.

List<Product> products = new ArrayList<Product>();

Use a concrete list type, e.g. ArrayList instead of just List.

List is an interface. You need a specific class in the end so either try

List l = new ArrayList();

or

List l = new LinkedList();

Whichever suit your needs.