Injecting a service in a java FX component

Question

Hi
I'm really thinking about using JavaFX as I found this technology simple and also I can reuse all of my java class in the fx script thus it's very interesting, and I'm really thinking on doing the jump.
But if I decide to really go in production with JavaFX I need to properly know what's the best way to manage the dependencies injection with javaFX.
I explain a simple case, I need to display a list of users in a fx component, and this users are living in a database. How will I manage this ?
The first and simplest option is to create a class UserManager with a static method : public static List<User> getUsers();
And inside my fx script I call UserManager.getUsers();
Well, this is working, but every serious developper know that calling every service statically is weak, for instance what if I need two UserManager class with connection to two differents databases, two different max results, two different creation date etc..
The second solution is to use a web service, but creating a webservice for a desktop application look artificial and involve extra work with no extra benefit (wrapping the request, unwrapping the answer, creating and registering the webservice ...), when a regular java call should do the work much quickly.
The good solution is to find a way to let a factory inject the service inside the fx script. But I really don't see how to do this.
What do you think about this ?

Answer 1

To my knowledge none of the DI frameworks support JavaFX yet but I could be wrong about this. I'm thinking about extending one of them but haven't gotten to that point in my own project where I need it yet. What you could do however is use java interfaces. JavaFX classes can implement a Java interface and generally this is the easiest way to allow Java code to interact with JavaFX code. So following along with your example what you could do is:
Declare the Java interface of your UserManager class and (build whatever concrete implementations you require)....
public interface UserManagerInterface {
    public List<User> getUsers();   // not static
}Also declare a Java interface of something that can accept a UserManagerInterface being injected:
public interface UserManagerClient {
    public void setUserManager(UserManagerInterface userManager);
}Have your JavaFX class implement this interface...
public class MyFXClass extends UserManagerClient {
    var userManager : UserManagerInterface;
    public override function setUserManager(userManager : UserManagerInterface) {
        this.userManager = userManager;
    public function initOrInitFromAnotherClass() {
        UserManagerFactory.createUserManager(this);
}So it doesn't really matter where your UserManagerFactory class is called from an the UserManagerFactory could be implemented in Java or JavaFX the point of the last method initOrInitFromAnotherClass() is simply to say that the factory is able to accept MyFXClass because it implements an interface that the factory can understand.
Hope this helps.
- Richard.