How to use a returned ArrayList in another method

Question

I think I am getting myself confused...I am calling a method (method B) which generates an array list. The calling is done from inside another method (method A). I am then trying to use the returned arrayList in method A but it seems to be empty. The arrayList generated in method B is not empty however so I think I've got some return ArrayList issue that I don't understand. Here is my code:

public void ExtractNew(String doc,String day) {

    ExtractTotal(docSlim,day);
}

public ArrayList<List<String>> ExtractTotal(String docSlim,String day) {
    ////Code for multidimensional arrayList creation omitted
            Arr2d.add(Arr);
            }
    }
    return Total;
}

So... where is Total defined + you don't fill it anywhere in ExtractTotal.. maybe you should return Arr2d? — Adnan Isajbegovic, May 06 '16 at 15:32
Ignore those people. You are not assigning a reference to the returned list. You should do something like this List> totalList = ExtractTotal(docSlim,day); — JavaHopper, May 06 '16 at 15:33
https://stackoverflow.com/questions/40480/is-java-pass-by-reference-or-pass-by-value — PeaceIsPearl, May 06 '16 at 15:34
A possible reason you immediately go the downvote might be because you are not camelCasing your variables. You are Capitalizing it, which to most of us would mean that is a class and not an object. It just makes your code difficult to read. — Rabbit Guy, May 06 '16 at 15:37
What is your variable `Total`? I don't see it defined anywhere. — Rabbit Guy, May 06 '16 at 15:39
Style note: you should use constant naming conventions for variables and methods. It will make youre code easier to read. You can see java convetions http://www.oracle.com/technetwork/java/codeconventions-135099.html — cyroxis, May 06 '16 at 15:40
@SebastianZeki maybe post a small code sample representing your problem rather than your large code block. — Nelson, May 06 '16 at 15:42

score 1 · Accepted Answer · answered May 06 '16 at 15:36

1

You're not adding to the Total ArrayList inside the ExtractTotal method.

Try this before returning it:

Total = Arr2d;

Assuming that Total is a class level variable here of course....

answered May 06 '16 at 15:36

Tom Mac

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Aha. That's the answer. – Sebastian Zeki May 06 '16 at 15:40

How to use a returned ArrayList in another method

1 Answers1