How to add elements to Java static ArrayList

Question

I have class like this:

public class Info{ 
public static String id;
public static ArrayList<String> poruceno;
}

And now I am trying to populate arraylist 'poruceno' from another class:

Info info;
info.id="bla bla bla" //works perfectly
info.poruceno.add("some string"); //Returns null pointer exception :(

I need to add elements from many other classes to this ArrayList 'poruceno' from class Info. Please help :)

You need to initialize your ArrayList. `poruceno = new ArrayList<>();` — Jared Rummler, May 20 '16 at 16:14
https://stackoverflow.com/questions/1005073/initialization-of-an-arraylist-in-one-line — Manas Ranjan Mahapatra, Feb 11 '19 at 15:13
https://stackoverflow.com/questions/1005073/initialization-of-an-arraylist-in-one-line — Manas Ranjan Mahapatra, Feb 11 '19 at 15:15
**Check this out :** https://stackoverflow.com/questions/1005073/initialization-of-an-arraylist-in-one-line — Manas Ranjan Mahapatra, Feb 11 '19 at 15:19

score 3 · Accepted Answer · answered May 20 '16 at 16:17

3

first at all, do init the list at the point of defining it:

public class Info{ 
    public static String id;
    public static List<String> poruceno= new ArrayList<String>();
}

then use it from other classes

Info.poruceno.add("Hello");
Info.poruceno.add("World");

answered May 20 '16 at 16:17

1 Answers1