Arraylist of arraylists

**mike_ledis** · 03-31-2012, 09:52 PM

Hello and congratulations for your job! Suppose that i declare an arraylist like the following

Arraylist stringArraylist<string>;

Is there any way to have an arraylist that holds arraylists like the uper?

**Norm** · 03-31-2012, 09:56 PM

Does the code compile?

like the uper?

What is "uper"?

**mike_ledis** · 03-31-2012, 10:07 PM

I need to declare an arraylist that holds arraylists of the following kind.
Arraylist stringArraylist<string>;

I didnt try because i dont know how to declare it.

**Norm** · 03-31-2012, 10:14 PM

Have you ever written an ArrayList that holds a String? You define the data type first followed by the name to be given to the object .
The symbol: String can be replaced with any other class name.

Check out the tutorial:
http://docs.oracle.com/javase/tutori...ybigindex.html

Find Generics and read on. There are two places to read in.

**jwolf** · 04-03-2012, 05:45 PM

Yes it is possible. An instance of the ArrayList class is declared, ArrayList<datatype> myList.
So you just need to make the an ArrayList of the type you want, i.e. if you wanted strings...

ArrayList<ArrayList<String>> list = new ArrayList<ArrayList<String>>();