javafx FXML and Controllers Passing parameters to FXML - using a controllerFactory
Example
Problem: Some data needs to be passed to a scene loaded from a fxml.
Solution
Specify a controller factory that is responsible for creating the controllers. Pass the data to the controller instance created by the factory.
FXML
<?xml version="1.0" encoding="UTF-8"?>
<?import javafx.scene.text.*?>
<?import javafx.scene.layout.*?>
<VBox xmlns:fx="http://javafx.com/fxml/1" fx:controller="valuepassing.TestController">
<children>
<Text fx:id="target" />
</children>
</VBox>
Controller
package valuepassing;
import javafx.fxml.FXML;
import javafx.scene.text.Text;
public class TestController {
private final String data;
public TestController(String data) {
this.data = data;
}
@FXML
private Text target;
public void initialize() {
// handle data once the fields are injected
target.setText(data);
}
}
Code used for loading the fxml
String data = "Hello World!";
Map<Class, Callable<?>> creators = new HashMap<>();
creators.put(TestController.class, new Callable<TestController>() {
@Override
public TestController call() throws Exception {
return new TestController(data);
}
});
FXMLLoader loader = new FXMLLoader(getClass().getResource("test.fxml"));
loader.setControllerFactory(new Callback<Class<?>, Object>() {
@Override
public Object call(Class<?> param) {
Callable<?> callable = creators.get(param);
if (callable == null) {
try {
// default handling: use no-arg constructor
return param.newInstance();
} catch (InstantiationException | IllegalAccessException ex) {
throw new IllegalStateException(ex);
}
} else {
try {
return callable.call();
} catch (Exception ex) {
throw new IllegalStateException(ex);
}
}
}
});
Parent root = loader.load();
This may seem complex, but it can be useful, if the fxml should be able to decide, which controller class it needs.
