Re: Newbie Question: ArrayLists and Referencing

From:

Patricia Shanahan <pats@acm.org>

Newsgroups:

comp.lang.java.programmer

Date:

Tue, 13 Nov 2007 09:59:01 -0800

Message-ID:

<fhcold$20ps$1@ihnp4.ucsd.edu>

Taria wrote:

G'morning!

I apologize for paraphasing my concern and bad naming conventions. I
should have labelled my code as psuedo. In any case, I created the
SSCCE (thank you for the correction) with the compiler error.

   import java.util.*;
    public class MyProg3 {
       public static void main(String[] args) {
         List table = new ArrayList ();
         ArrayList <Integer> data = new ArrayList <Integer>();
         data.add(1);
         data.add(3);
         data.add(4);
         data.add(2);
         table.add(data);

         ArrayList <Integer> node = new ArrayList <Integer> ();

       node.add(table.get(0).get(0));
      }
   }

import java.util.*;

public class MyProg3 {
   public static void main(String[] args) {
     List<List<Integer>> table = new ArrayList<List<Integer>>();
     List<Integer> data = new ArrayList<Integer>();
     data.add(1);
     data.add(3);
     data.add(4);
     data.add(2);
     table.add(data);

     ArrayList<Integer> node = new ArrayList<Integer>();

     node.add(table.get(0).get(0));
     System.out.println(node);
   }
}

The final println is just so that the program outputs something to check
that it did the right thing.

You need to think through the meaning of each data structure, and the
type will follow. "table" is supposed to refer to a list of lists of
integers, hence <List<List<Integer>>.

Patricia