in java and add comments:

Note: don't use collections, like list, HashSet (TreeSet), and HashMap (TreeMap)

Code that implements a set of items (strings) using a singly linked list. A set is a collection of items in which no item occurs more than once. code should externally support the following functions (the ones i'm stuck on):

1. Return the number of items in the set. (Iterative Solution on geeksforgeeks is what i was thinking)
2. Determine if an item is a member of the set.
3. Return a reference to a specific node in the set (given an item)
4. Determine the union (i.e. set of all distinctelements) and the intersection (i.e. set of all common distinctelements) of two sets.

• Include appropriate JUnit tests. (no main method)
• Count the time it takes to execute each of the above operations. Note: To count the time use system.currentTimeMillis().