Table of parameterized ArrayList

[Remedy]

Hello!
I looked in some tutorial about the parametrized arraylists and I have a problem when using them.
Here is my code:

		ArrayList <?>[] ts = new ArrayList <?>[2];
		for(ArrayList <?> A: ts) a = new ArrayList <String>();
ts[0].add("Hello");

And I have the following error on the add (): The method add (capture-of?) In the type ArrayList <capture-of ?> is not applicable for the arguments (String) Where am I wrong? Do you have some idea about it.

[NetworkeR]

Hello,
Just have a look at the following part of code of your

ArrayList <?>[] ts = new ArrayList <?>[2];

You said your test variable as an array of ArrayList type ? necessarily when you made the add (), java expects to have sth like ? not String. So to solve your problem replace all your? by String.

[Gunner 1]

Hello,
I am trying a similar sort of coding, I already tried it and it is not possible. In fact I based my experiment on this statement of java faq, section "Java 5.0 and parametrized types" (I said I use java 6). It is interesting that only the unconstrained wildcard allow the creation of tables configured. It is impossible to declare such an array of 42 lists of Double:

List <Double>[] tb = new ArrayList <Double>[42];

This limitation serves once again to protect the code at run time because it would otherwise be possible to manipulate the table as an array of Object and change the content without worrying about parameterized types:

Object[] tab = (Object[]) o;
o[0] = new ArrayList <String>();

[Remedy]

Hello,
My example code add to a list of strings in an array supposed to contain only lists of Double. That is why only wild cards are allowed:

List <?>[] tb = new ArrayList <?>[38];

So, I think the trick is that the definition, it has not seemed to pose problems, but for handling. If I forget the parametrization, I care less warnings everywhere, and I am obliged to caster in all directions.

[Linux-Us]

Hello,
If you want any warning you can always add

@ SuppressWarnings("unchecked")

So you'd have some work like this:

ArrayList <Double> []ts;
    @ SuppressWarnings("unchecked")   
	ts =new ArrayList[42];
	for (int i =0; I <42; i + +)
	    ts[i]=new ArrayList <Double>();

Anyways can not solve your problem but it takes away the warnings.

[HardWeaR]

Hello,
Otherwise you can make a ArrayList <ArrayList <Double>>. Basically your code look like this

ArrayList <ArrayList <Double>> ts;
ts =new ArrayList <ArrayList <Double>>();
ts.add(new ArrayList <Double>()); / / To add an item to ts
	ts.get(0).add(5.0);  / / Add values for the ts elements
	ts.get(0).add(4.0);

[Seoconsultant786]

Yes he is right the code is same of Arraylist i also use the same code for this when i need to make it.