Re: weird highlighting when i edit java code

It's because, for some bizarre reason, the author of the Java syntax
file that comes with Vim decided that all C++ keywords that aren't also
Java keywords (e.g. `register`, `delete`, `virtual`, etc.) should be
highlighted as errors in Java buffers. The only reason I can think of
for doing that is that if you happen to be a C++ programmer who is
learning Java, you might accidentally start writing C++ in the middle of
your Java code since the syntax of the two languages is somewhat
similar. Still, it's a really boneheaded thing to include in the default
Java syntax highlighting, and I'm surprised more people don't complain
about it.

When I encountered the same problem myself, I read the syntax script and
discovered that if you put `let java_allow_cpp_keywords = 1` in your
.vimrc, it will stop this silly behavior. That's probably the easiest
thing for you to do. Long term, it would be better if this feature were
removed altogether, or at least disabled by default.