Practical side of the ability to define a class within an interface in Java?

Question

What would be the practical side of the ability to define a class within an interface in Java:

interface IFoo
{
    class Bar
    {
        void foobar (         


        

Answer 1

I think this page explains one example pretty well. You would use it to tightly bind a certain type to an interface.

Shamelessly ripped off from the above link:

interface employee{
    class Role{
          public String rolename;
          public int roleId;
     }
    Role getRole();
    // other methods
}

In the above interface you are binding the Role type strongly to the employee interface(employee.Role).