othing about an all-Java CS degree really weeds out the students who lack the mental agility to deal with these concepts. As an employer, I've seen that the 100% Java schools have started churning out quite a few CS graduates who are simply not smart enough to work as programmers on anything more sophisticated than Yet Another Java Accounting Application, although they did manage to squeak through the newly-dumbed-down coursework. These students would never survive 6.001 at MIT, or CS 323 at Yale, and frankly, that is one reason why, as an employer, a CS degree from MIT or Yale carries more weight than a CS degree from Duke, which recently went All-Java, or U. Penn, which replaced Scheme and ML with Java in trying to teach the class that nearly killed me and my friends, CSE121. Not that I don't want to hire smart kids from Duke and Penn -- I do -- it's just a lot harder for me to figure out who they are. I used to be able to tell the smart kids because they could rip through a recursive algorithm in seconds, or implement linked-list manipulation functions using pointers as fast as they could write on the whiteboard. But with a JavaSchool Grad, I can't tell if they're struggling with these problems because they are undereducated or if they're struggling with these problems because they don't actually have that special part of the brain that they're going to need to do great programming work. Paul Graham calls them Blub Programmers.

But JavaSchools also fail to train the brains of kids to be adept, agile, and flexible enough to do good software design (and I don't mean OO "design", where you spend countless hours rewriting your code to rejiggle your object hierarchy, or you fret about faux "problems" like has-a vs. is-a). You need training to think of things at multiple levels of abstraction simultaneously, and that kind of thinking is exactly what you need to design great software architecture.

You may be wondering if teaching object oriented programming (OOP) is a good weed-out substitute for pointers and recursion. The quick answer: no. Without debating OOP on the merits, it is just not hard enough to weed out mediocre programmers. OOP in school consists mostly of memorizing a bunch of vocabulary terms like "encapsulation" and "inheritance" and taking multiple-choicequizzicles on the difference between polymorphism and overloading. Not much harder than memorizing famous dates and names in a history class, OOP poses inadequate mental challenges to scare away first-year students. When you struggle with an OOP problem, your program still works, it's just sort of hard to maintain. Allegedly. But when you struggle with pointers, your program produces the lineSegmentation Fault and you have no idea what's going on, until you stop and take a deep breath and really try to force your mind to work at two different levels of abstraction simultaneously.