Generic Resource Lookup Information
This answer discusses FXML location lookup, which is really just a subset of the generic resource lookup task in Java. The resource location is passed by the calling program as input to the FXMLLoader, so the resource lookup itself is part of your calling application code and not the FXMLLoader.
For thorough coverage of generic resource information (including recommended troubleshooting steps) for Java/JavaFX applications, please refer to:
Also useful, is the Eden coding resource guide:
Example usage
FXMLLoader loader = new FXMLLoader();
loader.setLocation(getClass().getResource("/main.fxml"));
Parent content = loader.load();
Location resolution options
Put all of your fxml in the src/main/resources directory.
loader.setLocation(getClass().getResource("/main.fxml"));
Put all of your fxml in a src/main/resources/fxml directory.
loader.setLocation(getClass().getResource("/fxml/main.fxml"));
Place fxml in a corresponding resource directory; e.g. src/main/resources/com/mycompany/myapp.
loader.setLocation(getClass().getResource("main.fxml"));
The last option assumes that the class from which you are loading the fxml is in the same relative location in the corresponding Java source hierarchy. For example, you might invoke the last load command from source com/mycompany/myapp/Main.java
.
FXMLLoader usage recommendations
Instantiate an FXMLLoader via new FXMLLoader()
rather than using
the static methods on the FXMLLoader.
- The static methods
become confusing when you want to get values (like instantiated
controllers) out of a loader.
Set the location on the instantiated FXMLLoader and call
load()
rather than loading from a stream using
load(stream)
.
- Setting a URL based location on the loader allows for resolution of
relative resources loaded in fxml and css files. Relative
resources do not resolve for a stream based constructor.
To derive a location based upon a class, use
getClass().getResource()
, as it is URL based, rather than
getClass().getResourceAsStream()
which is stream based.
IDE and Build Settings
Ensure that your IDE or build tool is copying the fxml files from the resource directory to the build output directory. For understanding Intellij settings for this, see: How to convert a normal java project in intellij into a JavaFx project.
A note on Java Jigsaw modular applications
See:
Specifically, don't write:
ComboBoxStyling.class.getClassLoader()
.getResource("/css/styleclass.css");
Instead write:
ComboBoxStyling.class
.getResource("/css/styleclass.css");
That is, get the resource from the class directly rather, NOT from the class loader. If you get resources from a class loader rather than the class, then there are additional restrictions on lookup based upon the module configuration. These restrictions can be hard to understand, see the documentation for the Class
and ClassLoader
getResource
methods for information if needed.