binary-search;binary-search-tree;custom-set;linked-list;simple-linked-list: use generics?

linked-list’s tests only insert and expect integers. However, the tests force the practitioner to generify the class.

We should:

1. remove type variables from the class signature in the tests and either expect Number or Integer
2. or expand the test suite to put all kinds of objects in the collection.

What do you think?

[rstockbridge]

I did simple-linked-list today, and I found the test suite’s handling of generics extremely confusing. Specifically:

• Unlike linked-list, the class is not explicitly specified as generic in the test suite. My IDE did not make the class generic when auto-creating the class. I only realized generics were necessary when I looked closely at the tests canReturnListAsArray() (which expects an Integer array) and canReturnEmptyListAsEmptyArray (which expects an Object array).
• I tried to proceed with a non-generic class treating the input values as ints, but got tripped up trying to write asArray(), which has to return a generic type array to pass the tests. I couldn’t figure out how to convert the values from ints to type T for array returned.
• (Side note: this was in interesting introduction into the difficulties of creating generic arrays in Java!)
• After consulting @stkent, I made the class generic, and was able to complete the exercise.

I think it would be very helpful to more closely align simple-linked-list with linked-list and make the class generic up front in the tests. I thought this exercise would be a simpler version of my solution to linked-list and was surprised at how much trouble I was having solving it.

[jtigger]

[Aside: I’ve been trying to encourage Rebecca to post issues here rather than telling me when she thinks an exercise is awkwardly placed… no luck yet, but I’ll keep asking her!]

Please do! Least she forget, she’s made significant contributions in mere suggestions (e.g. more exercises with starter code); great source of ideas!