Eclipse autocomplete not working in some Java files

Question

I have noticed that autocomplete is not working in some of java files in Eclipse. Also, the files where autocomplete is not working, display a hollow \"J\" as the icon for t

Answer 1

As an addendum to the @VonC answer, make sure that the Java files are part of the Inclusion pattern. I had a case where a build process was creating the project while only including .js files and not the Java files:

You can manually edit the inclusions via the Edit button. In my case, a fix was made to the build script to make it permanent.