In either java or c++, they're both very similar.
Check out the getRawButton method in the joystick class
http://wpilib.screenstepslive.com/s/...1881-joysticks
[edit]
If you're asking how to get the status of all buttons simultaneously, look at the getStickButtons method in the DriverStation class.
Source code is here:
http://team2168.org/javadoc/src-html....html#line.291
Not really sure what the format of the returned in it. I would assume it's that each bit is set corresponding to button id. The code isn't really commented... so you'll need to just try it out and see.