how can i put multiple classtypes in 1 array/arraylist

[Ciary]

hi,

i have a problem i can't figure out. i'm trying to create a tree structure in a class. to do that i have a class "Knod" and a class "Leaf". the class "Tree" is an ArrayList of arrays. and these arrays contain a boolean, a Knod or Leaf-class and 2 ints (defining the next Knod or Leaf)

public class Tree{
    private int init;
    private ArrayList<Object[]> boom;
 
    public Tree(){
        this.init = 0;
        this.boom = new ArrayList<Object[]>();
    }
 
    public void newLeaf(double[] waarden){
        Object[] arr = new Object[2];
 
                                //false = leaf
        arr[0] = new Boolean(false);            //true = Knod
        arr[1] = new Leaf(waarden);
 
        this.boom.add(arr);
    }
 
    public void newKnod(double[] waarden, int trueVal, int falseVal){
        Object[] arr = new Object[4];
 
                                //false = leaf
        arr[0] = new Boolean(true);            //true = Knod
        arr[1] = new Knod(waarden);
        arr[2] = new Integer(trueVal);
        arr[3] = new Integer(falseVal);
 
        this.boom.add(arr);
    }
}

as you can see i use an array of objects to make this work.
now i want to get the value of the Boolean. usually you would do

bool.booleanValue()

or in my case

this.boom.get(id)[0].booleanValue()

but since i made an array of object's he doesn't recognize this function.

so the actual question is, how can i put multiple classtypes in 1 array and still use all the functions?

tnx

[Dheeraj Joshi]

Can't you use vectors or any other collection frame works?

Regards
Dheeraj Joshi

[Ciary]

please explain that a bit further. as far as i know, a vector and arraylist are the same but from a different language (but i'm probably wrong) Enlighten me

[Nepomuk]

To come back to the original question, you'll have to cast the Objects. So in your example, that should be something like

((Boolean[]) this.boom.get(id))[0].booleanValue()

(Untested, but should work.)

Greetings,
Nepomuk

[Oralloy]

Ciary,

The difference between a Vector and an ArrayList is that the Vector class is synchronized. If you're writing a single thread program, you won't notice any difference between the two.

Hopefully that helps.

Luck!

[Ciary]

hi,

i already solved the problem my own way already. i just made 4 arraylists instead of an arraylist of arrays. that way i can change the type of each arraylist separately.

@Nepomuk: yup, that works. and it's probably better then my method. but since i'm just testing and efficiency isn't an issue i'll only change it if i get stuck.

@Oralloy: i am writing a single thread program so there shouldn't be a difference. but tnx anways. Honestly, i know the name 'vector' from C++ and physics. i had no idea what meaning it had in Java.

[Oralloy]

Ciary,

Synchronization requires CPU time. Use it when appropriate, but if it is not needed, then it's waste. But you probably already know that.

What's wrong with using an ArrayList<MyContainer>, where MyContainer is a service class which has all four attributes. Then you access them using a relatively simple construct:

ArrayList<MyContainer> myArrayList = new ArrayList<MyContainer>();
 
. . .
 
myArrayList.get(index).attributeN;

Luck!