Eclipse Java Content Assist not working

For me it works by doing prefrerences > general > keys > Restore Defaults

Dont know its crazy but thats what finally works after all the googling and trail following.

Regards, Manish

the Mylyn FAQ does mention:

Why do I get an error message when using content assist?

If after invoking Content Assist you see an error message dialog that states:

 The extension took too long to return from the 'computeCompletionProposals()' operation

this is most likely due to something interrupting the proposal operation (e.g. garbage collection). Ignore it if it does not recur, increase Eclipse’s memory if it does (e.g via -Xmx384M command line argument). See bug 141457 for more details.

Note that Mylyn should only add a trivial amount of overhead to content assist computation, however, the standard content assist mechanism will not report timeouts of this sort (i.e. taking longer than 5s to compute proposals).
If the system that you are working on is so large that increasing memory does not reduce the timings to avoid the message, you could also consider disabling the Mylyn-specific content assist, as described above, but if doing so please comment on bug 141457.

You can find good eclipse settings in this SO answer.
Since you have already try increasing memory, you can leave a comment on the bug 141457.

This could be related to the bug 281871, only fixed in eclipse 3.5.1 and 3.6.

I see it now. The problem is that code assist starts to use the Java model if the index is not yet up to date.

You can either wait until the indexer is done or increase the timeout by setting the 'org.eclipse.jdt.ui.codeAssistTimeout' Java environment variable when starting Eclipse, e.g.

 -vmargs -Dorg.eclipse.jdt.ui.codeAssistTimeout=60000

Looks like your mylyn install may be broken try removing the mylyn plugin and see how you get on.

I´ve runned onto the same, Content Assist not working under Eclipse 3.7.2. Up to this version is pretty stable, tough I don´t know how come it never worked for me.

I haven´t had any error message nor tip on why it wasn´t working and took me a while to find the 'Java Proposals' option.

It is on Eclipse Preferences -> Java -> Editor -> Content Assist -> Advanced.

Make sure that Java Proposals is checked.

You don´t wan´t repeated Java suggestions. Don´t check Java Non-Type Proposal nor Java Type Proposals.