Java "instanceof" to add multiple lists

Question

I'm currently trying to reorganize my code after reading that implementation is preferable to extensions. I'm currently trying to create a function that adds an object to the scene. To better define what each object is, there are several lists, such as a list for updating, rendering, etc.

private List<Updatable> updatables;
private List<Removable> removables;
private List<Renderable> renderables;
private List<Collidable> collidables;

I want to make a function in my Scene class as follows:

public void add(Object o) {
    if(o instanceof Updatable)
        updatables.add((Updatable) o);
    if(o instanceof Removable)
        removables.add((Removable) o);
    if(o instanceof Renderable)
        renderables.add((Renderable) o);
    if(o instanceof Collidable)
        collidables.add((Collidable) o);
}

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Answer 1

Factory, Map

static Map<String, List> maps = new HashMap<>();
static {
    maps.put(Updatable.class.getName(), new ArrayList<Updatable>());
    maps.put(Removable.class.getName(), new ArrayList<Removable>());
    maps.put(Renderable.class.getName(), new ArrayList<Renderable>());
    maps.put(Collidable.class.getName(), new ArrayList<Collidable>());
}
public static void add(Object obj){
    maps.get(obj.getClass().getName()).add(obj);
}

Answer 2

: add(Updateable u), add(Removable r), ..

Answer 3

, . Updatable, Removable, Renderable Collidable - . , . , add , . ( , .)

, , :

private List<Updatable> updatables;
private List<Removable> removables;
private List<Renderable> renderables;
private List<Collidable> collidables;

@SuppressWarnings("unchecked")
public void add(Object o) {
    try {
        for (Class c : o.getClass().getInterfaces()) {
            // Changes "Updatable" to "updatables", "Removable" to "removables", etc.
            String listName = c.getSimpleName().toLowerCase() + "s";

            // Adds o to the list named by listName.
            ((List) getClass().getDeclaredField(listName).get(this)).add(o);
        }
    } catch (IllegalAccessException e) {
        // TODO Handle it
    } catch (NoSuchFieldException e) {
        // TODO Handle it
    }
}

, :

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• , . , Foo implements Updatable, Removable, Bar extends Foo, getClass().getInterfaces() Bar . , ClassUtils.getAllInterfaces Apache Commons Lang.

Answer 4

, add , :

public void addUpdatable(Updatable updatable) {
    updatables.add(updatable);
}

public void addRemovable(Removable removable) {
    removables.add(removable);
}

// and so on

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Answer 5

@Jerry06, - getter.

private Map<Class, List> maps = new HashMap<>();

'maps' , .

private <T> List<T> get(Class<T> c) {
    return maps.get(c);
}

instead of using maps.get, I just use get (SomeClass.class). The function above will automatically convert it to a list with the correct item type. Then I could:

    get(Updatable.class).stream().filter(Updatable::isAwake).forEach(Updatable::update);

instead:

    updatables.stream().filter(Updatable::isAwake).forEach(Updatable::update);

I basically need a structure so that all lists can be well wrapped, and secondly, I could just say maps.add (SomeNewClass.class, new ArrayList ()), and then call it whenever I want.