After my recent update to the latest ADT the autocomplete features of eclipse suddenly stopped working.
Luckily a quick search lead to the indispensable stackoverflow.

The way to fix it is to go to:
Window -> Preferences -> Java -> Editor -> Content Assist -> Advanced

And check the boxes labeled “Java Proposals” and hit Apply.

Thanks to dchimento for the answer.

Link to the question / answer here:

eclipse – autocomplete has stopped working with android sdk – Stack Overflow.