Help understanding objects

Question

I have a netclass object:
public class netclass {
          public String     net="x";
          public String     clineL="x";
          public String     Sxy="x";
          public String      Exy="x";
          public netclass ( String net, String clineL, String Sxy, String Exy) {
               this.net=net;
               this.clineL=clineL;
               this.Sxy=Sxy;
               this.Exy=Exy;
I want to create space for 1000 of these objects so I tried:
netclass[] N = new netclass[1000];
When I try to assign a value to the object :
N[0].net = "debug";
I get a null pointer exception.
I am trying to define a structure and then create an array of structures.
Any help would be great.

Answer 1

This is your problem.
N[0].net = "debug";
At this stage you have an array that has space for 1000 netclass objects, but doesn't actually contain any objects yet.
So before you try to set the "net" field of N[0], you actually have to create an object at N[0];
N[0] = new netclass(...);
Now N[0] contains a netclass object. the rest(1...999) are still null.