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I'm just learning out Java and making a small console-game.

I have a Board class, which is done with 2-dimensional (Map) object array. Map represents "land" where I can have other objects on (Items, Monsters and so on..). Those objects are represented as ArrayLists in Map class (private instance variables). Map class has removeFromMap method, which removes a record from parameter specified ArrayList.

My Map instance variable:

private List<Monster> monsters = new ArrayList<Monster>();

My removeFromMap method:

public void removeFromMap(Monster monster) {

The problem is here, that if I'm going to have 100 objects, which can be on that "land" (Map), I will have 100 removeFromMap methods.

How can I make it more abstract, so I can just have one remove method to remove multiple of different objects?

Something like this:

public void removeFromMap(Object object) {
        if(object_type_of_Monster) // _type_of_ is not a real function of course, but is there something like this in Java?
        else if(object_type_of_Item)
            // cannot remove this object from Map

If someone has a better idea - let me know!

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closed as off-topic by Brian Reichle, Uri Agassi, rolfl, syb0rg, Jamal Feb 27 '14 at 22:53

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This question should be on Stack Overflow I think. There it would be better than on code review. –  Uwe Plonus Jan 11 '13 at 15:43

2 Answers 2

up vote 1 down vote accepted

Try to create a class ObjectOnMap which is the base class for Monster, Item etc.

Then you can write one method public void removeFromMap(ObjectOnMap object).

Your list is then List<ObjectOnMap>.


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Thank you for your answer, it's exactly what I need. –  Furlando Jan 11 '13 at 15:54

I would suggest to put it on stackoverflow, because code review is for reviewing existing code.

Anyway, the thing you search for is inheritance and superclass. Take a look at Java tutorials or any book/tutorial about object programming fundamentals.

In this case, it could probably be an IngameObject superclass.

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Yeah, I'm not very good at thinking in OOP yet. Yep, this superclass is exactly what I needed. –  Furlando Jan 11 '13 at 15:56

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