How do I fix a null pointer exception when adding to an array list?

Asked Apr 08 '17 at 03:08

Active Apr 08 '17 at 03:13

Viewed 28 times

I am trying to add to an array list using a passed in object, but I keep getting a nullpointer exception when executing the line "order.add(shape)" below.

public void addSquare(Square shape) {
    System.out.println(shape.toString()); 
    order.add(shape);
}

How do I fix the exception? Do I need to initiate shape somewhere?

edited Apr 08 '17 at 03:13

asked Apr 08 '17 at 03:08

user7835569

what is that "order." have you created that object? – Arvindsinc2 Apr 08 '17 at 03:12
order is the ArrayList I created that I am trying to add to @Arvindsinc2 – user7835569 Apr 08 '17 at 03:14
the stack trace from the NullPointerException might shed some light, but it pretty much has to be that order is null. – GreyBeardedGeek Apr 08 '17 at 03:16
@GreyBeardedGeek so how do I make it not null? – user7835569 Apr 08 '17 at 03:19
where do you intantiate and initialize this "order" object in your code? – mhasan Apr 08 '17 at 03:20
in another method: public TileManager() { ArrayList order = new ArrayList(); } @mhasan – user7835569 Apr 08 '17 at 03:21
there is your mistake...you are creating order locally inside TileManager() – Arvindsinc2 Apr 08 '17 at 03:27

How do I fix a null pointer exception when adding to an array list?

0 Answers0