<p>Since APCS is a Java-based course, that seems to be your only option. Unless your school offers other, non-AP, programming courses, that is. Self-studying any multitude of coding languages is possible, just search for it around the web. A few that come to mind are Stanford’s online lectures, which offer what is, essentially, the APCS equivalent (CS106a) and iPhone programming courses (though that may be more for the programmer than math major). MIT also offers similar courses, as do education start-ups on the net like Coursera and KhanAcademy. There are also innovative sites that teach HTML. Point is - you have an innumerable amount of resources at your disposal, so taking APCS is not necessary in the least. </p>
<p>In terms of the most preferable language, Java is great for learning to program with absolutely no prior experience. Others may say perhaps C or Python are better for getting your feet wet, but in my experience, Java is a suitable stepping stone. And learning to program is not irrelevant, because it requires one to many of the same mental tools that a mathematician uses, and you should take it to become a better mathematician, if anything. Think of it like cross-training, but far more applicable.</p>