I use Eclipse for Java development. I like the auto-activation feature because I can add all the letters and numbers so I can see class members while I'm typing; making it behave similarly to Visual Studio. If I don't add all of the letters and numbers to the auto-activation list, it will only pop up with class information when I'm typing the first letter after the '.' delimiter, and then it disappears.
The real problem arises when I'm typing in a variable name or something else. As soon as I hit space, the auto-complete types a bunch of crap following what I've typed in attempt to complete it. It's driving me crazy!
Any way to turn this off?
EDIT: It seems this answer is now outdated. It may work for old Eclipse versions. For any more recent versions refer to @ChrisP's answer from 2019.
Open menu Window, then Preferences. Follow path Java -> Editor -> Content assist. Now mess around with the settings to find your ideal setup. I believe what you'll want is to deactivate Insert single proposals automatically.