Re: Confused with the ArrayList

From:

Daniel Pitts <googlegroupie@coloraura.com>

Newsgroups:

comp.lang.java.programmer

Date:

Thu, 23 Aug 2007 15:52:35 -0000

Message-ID:

<1187884355.037152.34480@r23g2000prd.googlegroups.com>

On Aug 23, 5:21 am, dshankh...@gmail.com wrote:

Hello,

               ArrayList main = new ArrayList();
                ArrayList copy = new ArrayList();
                copy.add("Test1");
                copy.add("Test2");
                main.add(copy);
                copy = new ArrayList();
                copy.add("Test3");
                copy.add("Test4");
                main.add(copy);
                for(int i=0;i<main.size();i++)
                {
                        ArrayList temp = (ArrayList)main.get(i);
                        for(int j=0;j<temp.size();j++)
                        {
                                System.out.println(temp.get(j));
                        }
                }
                for(int i=1;i<main.size();i++)
                {
                        ArrayList temp = (ArrayList)main.get(i);

                                temp.set(0,"Test5");
                                temp.set(1,"Test6");
                }
                for(int i=0;i<main.size();i++)
                {
                        ArrayList temp = (ArrayList)main.get(i);
                        for(int j=0;j<temp.size();j++)
                        {
                                System.out.println(temp.get(j));
                        }
                }
        }

A note on style:

You should learn about and use Generics when dealing with collections.

List<List<String>> main = new ArrayList<List<String>>();
List<String> copy = new ArrayList<String>();

That way you no longer need to cast to ArrayList