Luke's answer is basically correct, but I will elaborate.
1) If you haven't done so already, you should install SceneBuilder first. https://gluonhq.com/products/scene-builder/
(If possible, take note of what location it installed to on your hard drive)
2) When you first choose "Open with SceneBuilder" by right clicking on an .FXML file from within IntelliJ, it will pop up a dialog asking you to find the SceneBuilder executable.
2a) For Windows users, I think the default location is C:\Users\yourusername\AppData\Local\SceneBuilder\SceneBuilder.exe
(However, perhaps it might also have installed under "C:\Program Files\SceneBuilder..."?)
Note: AppData
is a hidden folder, so you'll probably have to type it in if Windows won't let you browse to it, unless you change your folder view settings to always show hidden files)
2b) For Mac users, the default location is: /Applications/SceneBuilder.app
(If you try to browse to it, it may browse inside SceneBuilder.app like a folder, instead of letting you select it, so you should just type it in manually yourself.)
2c) For Debian-based Linux users, try /opt/scenebuilder/bin/SceneBuilder
.
3) HOWEVER, if you choose the wrong path originally when it asks you to find the SceneBuilder executable file, then you'll get an error whenever you try to choose "Open with Scenebuilder" from within IntelliJ after that.
To solve this, you should:
3a) For Windows and Linux users, go to File -> Settings -> Languages And Frameworks -> JavaFx
3b) For Mac users, go to IntelliJ IDEA -> Preferences -> Languages And Frameworks -> JavaFx
Then change the "Path to Scenebuilder" to the appropriate path.