The Oracle JDK for ARM no longer includes JavaFX¹⁾, so it must be installed separately.

1. Run java -version on the ComfilePi to verify the installation. If the Oracle JDK is not installed, run sudo apt-get install oracle-java8-jdk
2. Download an OpenJFX binary archive from one of the OpenJFX Community Builds. In this demonstration we will use OpenJFX 8u60 stable for armv6hf from https://chriswhocodes.com/.
3. Overlay the OpenJFX archive on top of the existing JDK by running the command sudo unzip openjfx-8u60-sdk-overlay-linux-armv6hf.zip -d /usr/lib/jvm/jdk-8-oracle-arm32-vfp-hflt/

Oracle's Java SE Platform Products are licensed under the Oracle Binary Code Licence Agreement. See also Java SE Embedded Pricing Explained.

A potential alternative to the Oracle JDK is OpenJDK.