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
– Jared Rummler, Commented May 20, 2016 at 16:14
Initialize the Arraylist as poruceno=new ArrayList<String>(); — Buddha
– Buddha, Commented May 20, 2016 at 16:14
Check this out : stackoverflow.com/questions/1005073/… — Manas Ranjan Mahapatra
– Manas Ranjan Mahapatra, Commented Feb 11, 2019 at 15:19

ΦXocę 웃 Пepeúpa ツ · Accepted Answer · 2016-05-20 16:17:15Z

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, 2016 at 16:17

48.4k17 gold badges77 silver badges102 bronze badges

Sign up to request clarification or add additional context in comments.

1 Comment

Ouch... Tnx mate! :)