Question

I am trying to set a callback for a method in JavaFX: http://docs.oracle.com/javafx/2/api/javafx/fxml/FXMLLoader.html#setControllerFactory(javafx.util.Callback)

This is the signature:

public void setControllerFactory(Callback<java.lang.Class<?>,java.lang.Object> controllerFactory)

I’ve tried different kind of setups, this is the latest and I can’t seem to get it to compile at all, there’s always something that doesn’t match the signature:

val loader = new FXMLLoader()
loader.setControllerFactory(new Callback[Class[_], AnyRef] {

})

This one gives me:

error: object creation impossible, since method call in trait Callback of type (x$1: Class[_])AnyRef is not defined

How would I write that Java example in Scala?

Answer 1

As the error message says, you need to define that method in your anonymous class:

loader.setControllerFactory(new Callback[Class[_],Object] {
  def call(c: Class[_]): Object = {
    // your implementation
  }
})