lsp-ui VS lsp-java

Emacs has code peek.

With lsp-mode it has that little window: https://emacs-lsp.github.io/lsp-ui/#lsp-ui-peek

Personally I use eglot with consult which temporarily switches the entire buffer to do the "peek" functionality rather than popping up a tiny window: https://github.com/minad/consult

I couldn't reproduce it with my setup. Just for the reference, I use Doom ba35f12be with Emacs 29.0.50 76b7a5936 on Debian 10. Specifically, lsp-mode 68bdac0f8, lsp-ui d8cce7dc1. I use monospace Iosevka TTF font for both italics and regular faces.

rustic + lsp-mode + lsp-ui leads to a pretty slick IDE-like experience for Rust. All of these should work pretty okay out of the box!

I think you should be customizing LSP-UI specifically for the grey text issue, but I haven't used it recently enough to remember: https://github.com/emacs-lsp/lsp-ui

lsp-java mode should handle most of that: https://emacs-lsp.github.io/lsp-java/

Speed of Emacs on Java codebases can be faster than IDEA? With features of lsp-java ? How could it possible~~

I dunno about the netbeans LSP server but I use eclipse JDT language server from Emacs and it works pretty well https://github.com/emacs-lsp/lsp-java

According to lsp-java, variable lsp-java-format-settings-url specifies the url or file path to the eclipse formatter xml settings. This file eclipse-java-google-style.xml works fine in vscode and eclipse. The expected behavior is line longer than 100 is splited to a new line. In spacemacs, split length is still the default 120.

I see that I can configure DAP mode for a new server. This references "java", which I assume points it to dap-java.el within lsp-java.

You should check out emacs-lsp/lsp-java, it's exactly what you want.

Unfortunately I don't use snippets for the settings, but this must be configurable by the client LSP I've already seen people who can do this kind of thing with lsp-java, I wouldn't be surprised if you can also do it with lsp-python.