Container exercise 7, 
 * Exercise 7: (3) Create a class, then make an initialized array of objects of your class. Fill
a List from your array.
* Create a subset of your List by using subList( ), then remove this
subset from your List.
* if other exception pops up instead of defined exception, maybe switch a way to think about polyhpism is a good way.Duplicate elements will also be removed
 */