I think lsp integration[0] can get you pretty far, but also if you use LLM features a la Copilot, I use ellama[1] for that. If there are other features you think you will miss, maybe I can ease your mind about those as well :)

[0] https://github.com/emacs-lsp/lsp-mode

[1] https://github.com/s-kostyaev/ellama

I used Eclim (https://github.com/emacs-eclim/emacs-eclim) for a bit, but I'm guessing, like the sibling comment said, that the current preferred solution would be to use LSP.