stack overflow

I've never had much need to write recursive functions in my programming career; I've written one perhaps two or three times, all told. Hence, I haven't paid them much attention, and still don't really know much about them.

It turns out that interviewers are quite keen on asking questions about recursion; perhaps this is because there's a heavier focus on them in CS classes than there is a use for them in reality?

The first time I encountered a question about recursive functions during an interview, it kind of threw me. Why ask a question about something so rarely used? My response was that, yes, I've written them, but rarely, and I try to avoid it when possible because I find them confusing - I have a fear of writing something that will result in an infinite recursion in some subtle case. It was during this interview that I learned that recursive functions can lead to stack overflows. Thereby proving that interviews can be useful, at least as learning experiences.

Well, today I caused my very own stack overflow by creating a recursive function, albeit unknowingly! I had created a Java class which extended another class, which mostly had getters and setters. The intention was to eventually implement these methods in the child class, but meantime I had the child class override the parent's methods, and just had them return the results of the super class methods. For example, I had the getFoo() method call the superclass method, super.getFoo(), and so on. Only, in one case, I inadvertantly left out super and had the getBar method return getBar - so the method called itself recursively. When I ran the code, I immediately saw this huge stack trace in the output. At the top it said "Exception in thread ... java.lang.StackOverflowError. This was followed by 1024 repeated lines giving the method which had generated the error.

I don't recall ever experiencing this in my entire career, and I could immediately see what had gone wrong, so I found it very entertaining (perhaps I am too easily amused).