Hello everyone,

i have a NullPointerException error in my code at line4.
Can someone guide me please.
the code is here:Click Here

Thank you very much
NS

operationsPrioriteToDoListModel = dyndefn.getOperationList();

most likely because you didn't instantiate dyndefn, but that's impossible to say based on the code you show.

Where did you defined this variable 'operationsPrioriteToDoListModel' ?
May you provide us with the full code?

Thank you

Yes i define this variable in the beginning of the code:

public class SimulationMain extends javax.swing.JFrame {
private DefaultListModel operationsPrioriteToDoListModel = new DefaultListModel();

Thank you for your help.

and what about dyndefn? the operationsPrioriteToDoListModel isn't the problem here.