NullPointerException on list.add

Question

I am getting a NullPointerException at the modelData.add(i, es) method. I know from debugging that es isn't null. I'm really confused, thanks.

public class EventTableModel extends AbstractTableModel {

    //private int rowCount = 0;
    protected List<EventSeat> modelData;
    private static final int COLUMN_COUNT = 3;
    private Event e;
    Event j = GUIpos.m;
    int i = 1;

public EventTableModel(Event e) {
    this.e = e;
    try {
        System.out.println(modelData);
        for (EventSeat es : e.getEventSeats()) {
            modelData.add(i, es);
            i++;
        }
    } catch (DataException ex) {
        Logger.getLogger(EventTableModel.class.getName()).log(Level.SEVERE, null, ex);
    }

}

Where is `modelData` initialised? Shouldn't there be a `modelData = new ArrayList();` somewhere? — srgerg, Mar 08 '11 at 00:09
possible duplicate of [What is a Null Pointer Exception, and how do I fix it?](http://stackoverflow.com/questions/218384/what-is-a-null-pointer-exception-and-how-do-i-fix-it) — user2864740, Oct 11 '14 at 21:42

score 74 · Accepted Answer · edited Jun 02 '17 at 17:04

74

You need to initialize a List to not get the NullPointerException.

protected List<EventSeat> modelData = new ArrayList<EventSeat>();

edited Jun 02 '17 at 17:04

Akshay Talathi

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answered Mar 08 '11 at 00:07

Erik

88,732
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189

score 9 · Answer 2 · answered Mar 08 '11 at 00:08

9

Try

protected List<EventSeat> modelData = new ArrayList<EventSeat>();

answered Mar 08 '11 at 00:08

Sheridan

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Bonus points if you change this to match the other two answers; I don't think you can instantiate a `List` like that. – phooji Mar 08 '11 at 00:09

Piyush Mattoo · Answer 3 · 2011-03-08T00:18:11.500

6

On the first look, seems like modelData has not been instantiated. I would instantiate the modelData like:

protected List<EventSeat> modelData = new ArrayList<EventSeat>();

FYI.. In Java 7 there will be a new syntax you can use- someObject?.doSomething();

edited Mar 08 '11 at 00:18

answered Mar 08 '11 at 00:11

Piyush Mattoo

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I don't think e.getEventSeats() returns null (or returns an iterator containing a nulll element). If that were the case the code would terminate at the start of the `for`. – phooji Mar 08 '11 at 00:15
Sure..wrote the solution in haste. Thanks for pointing this out. – Piyush Mattoo Mar 08 '11 at 00:19

score -1 · Answer 4 · edited Jun 30 '21 at 06:10

-1

The modelData was not initialize.Try initialing it using the below snippet.

protected List<EventSeat> modelData=new ArrayList<>();

Thanks

edited Jun 30 '21 at 06:10

Slycreator

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answered Jun 29 '21 at 09:50

user16341386

1

Welcome to stackoverflow. Your answer doesn't add anything that's not covered by other answers. You can upvote them if you agree with them. See also [answer]. – Robert Jun 29 '21 at 19:49

NullPointerException on list.add

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