most of the applications that you run on windows or the mac are written in C, C++, C#, or VB.
this is because they distribute well - they compile to an EXE or other binary appropriate to the OS. that also means you can write an installer easily for it because it is a binary.
C++ is not a fun language to write GUI applications in. it is mainly designed for command-line applications, but typically the OS calls are made available to you, such as all the Win32 calls, or kernel calls, etc, which may include GUI stuff.
java is not like that. applications can be distributed as EXE's, but it requires a 3rd-party program to do it (download one of several tools off the internet), and they probably have to be .jar files in the first place. java is not fun to compile. each project requires a custom batch file. the manual is not laid out well, so it is hard to use.
best to learn Java by buying books on Swing, etc, and making sure the books you buy aren't paperweights (they have real substance and teach you something real and give usable examples).
I didn't take computer science, I took Computer Engineering. that was a combination hardware/software engineering degree. I suppose I should have stuck with computer science maybe, since I am mostly a software guy. that was 10 years ago. today you will likely learn C++ and Java both, since both languages are in demand.
Java is used on web servers (JSP) along with Java clients sometimes to deploy major applications such as yahoo mail.
either Perl or C++ may be used in mission-critical e-commerce apps (perl I would think). C++ is used in programs that require network communication protocols.
I would say tinker with and learn both if you can. both will benefit you in a career. In a job description for a person who writes stepper motor drivers, the person had to write for multiple platforms (windows, linux), and in multiple languages (Java, C, C++).
I thought the extra information might be of interest to you.
the 64-bit c++ mingw compiler is buggy(crashes a lot), but it compiles OK.
the 32-bit C++ mingw compiler works great.
for Java you will need the JDK.