Question

I have constructed a class to mimic a C# struct:

public class Favourite {
    protected  String favName;
    protected  String favText;
    protected String favDelay;
    protected GeoPoint favPoint;
    protected Uri favUri;
}

I want to create an array of this class:

Favourite[] fav;

When I try to access this array:

fav[s].favName = bufr;

I get a NullPointerException. bufr does contain data. I have tracked it down to accessing the array as the following code:

fav[s].favName = "";

also produces a NullPointerException.

I have searched high and low for some indication as to whether or not what I am doing is allowed but cannot find anything.

I suppose my questions are:

Are you allowed to create an array of a class object?
If so, how do you refer to that array?

I know I could do this using five separate arrays of the variables but I feel that putting them into a class gives a better structure and is more elegant (I like elegance).

Answer 1

The problem is that fav[s] is null.

I don’t know about C#, but in Java, you have to initialize the elements of the array individually; you can’t just declare the array and get it automatically filled.

You’re going to have to loop through fav and fill it with new Favourite objects.

Either assign fav[s] = new Favourite() the first time you use fav[s], or initialize it all at once by doing

for (int i = 0; i < fav.length; i++) {
  fav[s] = new Favourite();
}