Teaching Languages

Java's never been my favorite language either for using or for teaching.

As a programmer, after starting with languages like Fortran and Pascal, I really cut my teeth with C. More recently, Python has been my go to language to get real work done.

From a teaching point of view most languages have good points and bad ones. When the AP class went from Pascal to C++ I lamented losing the simplicity and the low cost of entry. On the other hand, C++ gave us objects (not that I'm a big OOP guy), separate files, the ability to use tons of real world libraries and more.

Moving to Java simplified things in a number of ways but removed memory management. If we didn't teach that along with the stack frame in our Systems class, I think our kids would be missing something very important.

I was reminded of some of Java's limitations as a teaching language over the past couple of days.

As posted earlier, I had my AP students create their own class to mimic the Java ArrayList. Before introducing the ArrayList in Java, I wanted to introduce generics:

public class myList<T> {
  T[] data;
  public myList() {
    data = new T[10];
  // much more not shown 

Turns out, you can no longer do this.

After doing some searching, there does appear to be a way to get this effect but it was certainly not something I wanted to do with my classes. I was looking for something more pedagogically sound - an easy way to show the concept and a way to springboard to an ArrayList.

Oh well...

So, we finished ArrayLists and I was mapping out a plan for Monday. I thought Radix sort would be cool -- we already introduced using an array to tally votes when we did the mode. This seemed to be a natural extension. It would combine Arrays and ArrayLists and illustrate when each is appropriate.

First the kids would set up an array of 10 buckets, each being an ArrayList:

public class Buckets {
  ArrayList<Integer>[] buckets;
  public Buckets() {
    buckets = new ArrayList<Integer>[10];
    for (int i=0;i<10;i++)
      buckets[i] = new ArrayList<Integer>();
  // much more not shown 

Unfortunately, Java type safety once again reared its ugly head. OK, maybe not ugly to a programmer, but ugly to a teacher. You can't do it. You can do it with an old school ArrayList without the generic: ArrayList[] buckets = new Arraylist[10]; but of course, this leaves you open to type mismatch problems.

Once again, Java provides a convoluted workaround that might be fine for a professional programmer, but for a student, it would be nuts.

I might go ahead with the Radix sort lesson anyway, we'll see, but it would be nice if I could teach this level of course without having to fight the implementation language.


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