I have installed Apache Netbeans 9.0 recently in Mac running macOS Mojave. I am trying to change the Netbeans theme to "Dark Look And Feel Themes"
I can recommend you to check NetBeans Themes website. It allows you to design and download your own themes.
Twilight theme is a good example:
Updated 4/11/19:
Based on a comment from @superbiji below, Darcula + Norway Today works fine with NetBeans 11.0.
Updated 2/7/19:
Note that the answer below applies only to NetBeans 9.0. The situation is a little different on NetBeans 10.0 where the Dark Look and Feel plugin (themes "Dark Metal" and "Dark Nimbus") also worked fine. See Projects, Files, Services, Navigator color background.
I tried to download then manually install those two plugins on NetBeans 9.0, but it didn't work for me:
However, there is an alternative approach that works for Darcula (but not for Dark Look And Feel Themes). It is a simple two step process:
To make the plugin available:
In the Update Center Customizer dialog that opens:
Click OK to make the plugins associated with that URL available for installation.
Now click the Available Plugins tab. You should see a lot of new entries, including one for Darcula LAF for NetBeans:
Check that entry and click Install, just as you would on NetBeans 8.2.
NetBeans 9.0 should restart using the Darcula theme:
Notes: