adding a Double value to a list

[Ram Bu]

Hi,

The following code is throwing a NullPointerException

import java.util.List;
public class Test {

public static void main(String[] args) {

List l = null;
double d = 2386870.0;
l.add(new Double(d));

}
}

Can someone shed some light on why this is happening and how to fix it.

Thank you.

[Scott Selikoff]

A list is an object in java and all lists must be created. When you declare a list such as:

   List l = null;

you only created a pointer to a list, not the list itself. In this case, you create a pointer to a list l, and assign it a value of null. You must assign the pointer the value of a real list in order to use the list.