Nifty: reference between application and controller (solved)


I have a class called Engine that extends SimpleApplication and handles most of the game. I also have a controller for the Nifty gui that extends Engine and implements ScreenController. Now my problem is that I need to call methods in Engine in order to affect the game through the gui, and by extension the controller.

I can’t seem to figure out how I am supposed to get a reference to one class from the other. I read somewhere that I should extend the class that extended SimpleApplication but that doesn’t seem to resolve anything. As far as I can see, the application and controller have no relationship and I don’t know how the innards of Nifty works.

Isn’t there some way I can call Engine’s methods from the controller?

I’m hopelessly stuck and have been for hours. Please help :slight_smile:

You need to either pass an object of the desired type and save it as a local variable in the other class or create a static accessor:

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Hi normen.

I didn’t find the original post when I was searching the forum and wiki for an answer - sorry about that.

Well your post completely solves my problem. Thanks a lot :slight_smile:

I ended up with the following code:


private static Engine staticApplication;

public Engine(){ }

public static Engine getApplication(){

if(staticApplication == null)

staticApplication = new Engine();

return staticApplication;


public Engine(Main m) {

this.m = m;

staticApplication = this;



Here’s how I did it (I think it’s an ok way…)

Just declare the Main class (Engine in your case) as a class variable, and make sure the controller class is in the same package. e.g.:


public class Main extends SimpleApplication {

static Main app;

// main() method, controllerClick() method, etc.


public class ScreenControllerRotate implements ScreenController {

public void onClick(){;


//code etc.



I’m a noob programmer though so let me know if I have some bad practices in this ‘kludge’.