In java,

Implement a SimpleSet class that holds Strings. Use an Array as the Data Structure that holds the data inside the Set. In this case, Sets do not allow duplicates, but are unordered. You need only implement the following methods:

add Add an element to the set if it does not already exist

remove If an element exists, remove it from the set and return it. Otherwise, return null

toString Allow the user to print a Set to see all the contents of the Set

concatenate Take a set as an argument. Add all the elements from the argument set to the calling set, while not allowing duplicates