Generating dynamic object names within an arrayList in java

Question

I'm doing the last challenge on this forum post called 'graduation' except in Java instead: http://www.cplusplus.com/forum/articles/12974/

I've basically stumbled across a problem where if I have an arrayList of bunny objects that spawns new offspring based on the amount of males and females, I need to give each new offspring a dynamic name for the list or the compiler goes mental and throws a ConcurrentModifierException (which I'm assuming is because it's trying to go through multiple objects that have the same variable name).

The only way I can think of is by making a Bunny object array like saying:

bunnyList.add(bunny[i + 1])

Where i is the kind of 'global' id for all the bunnies. But the problem is that if I add it to the list it's illegal. To be honest, I'm not sure why either since I set the array list to be of type bunny array rather than just plain old bunny.

public class Bunnies {

    private static ArrayList<Bunny[]> bunnyList = new ArrayList<Bunny[]>(); 
    private static Bunny[] bunny = new Bunny[500]; //gives it a kind of id
    private static int i = 0; //global bunny counter

    Bunnies(){

        //init the game list.
        initBunnyGameList();
    }

    private void initBunnyGameList(){

        for (int i = 0; i < 5; i++){
             bunny[i] = new Bunny();
             bunnyList.add(bunny[i]); //ILLEGAL :(!
        }

    }
}

Also doing it this way seems like a massive waste of memory to create an array space for 500 possible bunny objects only to ever use ONE space as an identifier. But I can't seem to think of a way to name each variable dynamically in any other way. Really, what I need is a way to generate variables with a number on the end when I make a bunny so they're all individual no matter what.

Any suggestions hombres?

Alexis C. · Accepted Answer · 2013-10-23 18:10:10Z

2

bunny[i] is actually a Bunny object, not an array of Bunny objects.

private static ArrayList<Bunny[]> bunnyList = new ArrayList<Bunny[]>();

should be

private static ArrayList<Bunny> bunnyList = new ArrayList<Bunny>();

answered Oct 23, 2013 at 18:10

Alexis C.

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2 Comments

ach Over a year ago

Also, for the OP: It's a good practice to type your variables as interface types unless you REALLY need functionality specific to the implementation type: private static List<Bunny> bunnyList = new ArrayList<Bunny>();

Jake Gabb Over a year ago

Haha that was unexpectedly simple but it's worked! I can see where my confusion was too. I guess I was just using ArrayList because it's what I know, I've only really just got into this more advanced OO stuff, but I can see where you're coming from, I'll make sure to look in the future at what I actually use in the API and scale down or up based on what I find x

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