Running

To run this application use ./gradlew jfxRun.

Install prerequisites

First, make sure you have JavaFX installed. I use OpenJDK on Ubuntu. OpenJDK ships with Ubuntu 16.04, but despite JavaFX being a part of the JRE, it doesn't ship with the standard OpenJDK package. Instead you should run:

sudo apt-get install openjfx

This will add JARs to /usr/lib/jvm/<JAVA VERSION>/lib.

IntelliJ IDEA

I was using IntelliJ IDEA to develop and I discovered I had to do some additional steps to notice I had installed JavaFX:

1. In the newly created project, go to File → Project Structure
2. Remove the JDK and recreate it, to make sure the classpath includes the new JavaFX jars
3. Make sure the module is targeting Java 8

You may not have to do these steps - I created the project before installing JavaFX, which may have been the root of my problems.

For more information

See this blog post