>
> > https://youtu.be/4UcPIdTJLOM .
>
> Note that Semantic will cache the AST between sessions, so if you've
> loaded that file before, it will just load the cache.
>
First use parse/build delay is an inescapable and acceptable  situation in
Java world. Even popular IDEs like Eclipse do that.
While Emacs will only parse current and relevant files, Eclipse insists on
"building" the complete project.

It is also
> very old, and at that time (around Java 1.4 or so) the language was
> still very easy to parse (it doesn't support generics, for instance).
>
Additional info - I've added support for annotations and generics. It's
shown in the demo https://youtu.be/4UcPIdTJLOM?t=50 .
Only Enum is pending.