prodigy, then please read follow-up posts before quoting like that. I backed off from the comment a bit, as yes, saying it never took off was quite outlandish.
Of what you said, yes, C++ (is) more efficient as it's not running through the "virtual machine", but that was more-so in the past.
Read up on it (an article from 2003).
OnlyCurious, many colleges rely heavily on Java as it's a great intro language and a huge community supporting it (not to say C++ doesn't, but, go check out the resource-quantity comparison on Google).
Then you must realize, some things you're indirectly making comparisons to ("big companies"), such as an operating system, cannot be coded in any part by Java for the obvious reason of the necessary virtual machine. So yeah, don't except to work with Microsoft and get away with knowing solely Java. Then again, if you like what you do, and in being a programmer, you should - you'll have experience with all of the common stuff, from binary, assembly up through the latest C#.
As far as big companies using Java, do some more research, and you may be surprised.