java's --version option seems to be undocumented. The documented one is -version. Try java -v<Tab>.

java --v<Tab> should also suggest -version if you enabled approximation in the completion configuration:

 $ java --vTab Completing corrections -verbose:class -verbose -- print class information -verbose:gc -- print gc information -verbose:jni -- print JNI information -version -- print version 

See compinstall for an easy way to configure it.

See info zsh bashcompinit for how to use bash completion functions within zsh, but note that bash completions are generally inferior to zsh ones. You'd only want to use it for the cases where completers have been written for bash but not zsh.

java's --version option seems to be undocumented. The documented one is -version. Try java -v<Tab>.

java --v<Tab> should also suggest -version if you enabled approximation/corrections in the completion configuration:

 $ java --vTab Completing corrections -verbose:class -verbose -- print class information -verbose:gc -- print gc information -verbose:jni -- print JNI information -version -- print version 

See compinstall for an easy way to configure it.

See info zsh bashcompinit for how to use bash completion functions within zsh, but note that bash completions are generally inferior to zsh ones. You'd only want to use it for the cases where completers have been written for bash but not zsh.