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EGrant
EGrant wrote ...

2016/10/24

Calling World public method from Actor subclass

EGrant EGrant

2016/10/24

#
I have created a public method in a World subclass, and I am unable to call the method from within an Actor subclass method. The error I get is "cannot find symbol". I have chosen to replicate this problem in a book_scenario: Newtons-Lab-1 in the constructor for the SmoothMover subclass as follows: 
    /**
     * Default constructor.
     */
    public SmoothMover()
    {
        this(new Vector());
        getWorld().sunAndPlanet();
    }
I found this inconsistent since I have always been able to call World methods (such as addObject) from within an actor subclass so long as I reference the World object. The problem I am having in my scenario is the same as this one. I am able to call the method directly when I right-click on the World from the drop down box (just as I am able to within the Newtons-Lab-1 scenario), but not able to call it from within an Actor subclass method. Appreciate the help, Elizabeth
danpost danpost

2016/10/24

#
The reason methods like 'addObject' works when using 'getWorld' is because 'getWorld' returns a World object (or null). As a World type, methods of the World class are accessible. However, for methods of a subclass of World, you need to inform the compiler where to look for that method. This is done by typecasting. If the name of the subclass were MyWorld, then: 
((MyWorld)getWorld()).sunAndPlanet();
or 
MyWorld myWorld = (MyWorld) getWorld();
myWorld.sunAndPlanet();
EGrant EGrant

2016/10/24

#
Thanks Dan. I haven't taken advantage of World subclasses much yet. The explanation is totally reasonable since, after all, the method belongs to the subclass not World, unlike the addObject method.
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