I am currently working on an application using javafx for its UI. I am using java 9. When I pulled from github to continue development on my new computer and compiled, there were compilation errors at all references of javafx classes, and only javafx classes.
I searched in the jdk in external resources, and the javafx package was indeed where it was supposed to be. I also made a new project using the same jdk and opened a javafx window, which worked fine. This tells me that this is a project-specific issue, rather than a system issue.
Does anyone have some insight into this? Thanks.
EDIT
I am using Intellij comunity Ed. The error list was expansive, but here are a few
Your IDE may have set the project up as a "modular" Java 9 project. In modular projects, you specify which other modules the project depends on, and which packages in your module(s) should be exposed to other modules. A good general tutorial on modules is at the OpenJDK wiki.
If there's a module-info.java file in the classpath root, you need to explicitly state that your module requires access to the appropriate JavaFX modules. It may be enough just to add
requires javafx.controls ;
to this file: that will give you access to the javafx.controls module, and the modules on which it depends (javafx.graphics and javafx.base). Depending on your project, you may also need
requires javafx.fxml ;
and/or
requires javafx.web ;
etc.
来源：https://stackoverflow.com/questions/48853477/java-cannot-find-javafx-classes-although-present-in-jdk