.FXML File Extension
File TypeFXML Source Code File
What is an FXML file?
Contains code written in the FXML programming language developed by Oracle Corporation; used to create the user interface of a JavaFX 2.0 application; based on XML which uses the .XML file extension.
JavaFX is used to develop rich internet applications and can use FXML to develop its user interfaces as opposed to writing it using procedural code. The FXML files is used alongside .JAVA files to create an application.