newbie Threads and JDialog

       Hello all
  I've been working with Java for one year and I'm a newbie with
threads, I have the following problem which I suppose you experts can
help:

   I have a JDialog extension which I create some JTabbedPane with
some tables. This JDialog and these tables, send data to other class
which performs some calculation. Now I have a problem and I suspect
that its related with threads.
The button actionPerformed listener call a JDialog method that send
data and also "tells" the table to send its data to the calculation
class. After the table send the data, the constructor of the external
calculation programm fails. I'm listing in a reduced way my code:

In the Main (just the part related with the JDialog)
// in the declaratins:
public InputsIntegrationDialog inputIntDiag;
..
..
..
if (operationIndex == INTEGRATION){
            if(inputIntDiag == null){
                inputIntDiag = new InputsIntegrationDialog(this, getGraph());

            }
            else
                                inputIntDiag.setVisible(true);

The InputsIntegrationDialog class resumed:

public class InputsIntegrationDialog extends JDialog implements
ActionListener{
    public InputsIntegrationDialog(Window owner, VRGraph grap1) {
        super();
        this.tabbedPane = new JTabbedPane();
        fixedCostsTable = new IntegrationTable();
        variableCostsTable = new IntegrationTable();

        variableCosts = makeTextPanel(res.getString("variableCosts"));
        tabbedPane.addTab("variableCosts",variableCostsTable );

        Box okCancel = Box.createHorizontalBox();

        ok = new JButton(res.getString("Ok"));
        ok.addActionListener(this);
        runBut = new JButton(res.getString("Run"));
        runBut.addActionListener(this);
.. ..// box layouts etc...

        Container contentPane = getContentPane();
        contentPane.add(tabbedPane, BorderLayout.CENTER);
        contentPane.add(vertBox, BorderLayout.PAGE_END);
        this.pack();
        this.setVisible(true);
    }

    public void runOPT(){
        // initialize the calculation class (hiden)

        //send the data from the tables to the calculation

                variableCostsTable.sendDataToOpt(data 1, data 2);
// in the line bellow the problem happens!!!!!!!!!!

        solver1.setNLP(nlp1.getNLP());
    }
    public void actionPerformed(ActionEvent e){

        System.out.println("Action: " + e.getActionCommand().toString() );
        if(e.getActionCommand().toString() == "Ok"){
            this.setVisible(false);
        }
        else if(e.getActionCommand().toString() == "Run"){
// This Line calls runOpt() and inside runOPt the crashes happen
                int res = this.runOpt();
            if( res1 >= 0){
                JOptionPane.showMessageDialog(this,
                        "Optimization sucessful","Message");
            }
            else
                JOptionPane.showMessageDialog(this,
                        "Optimization NOT sucessful","Error");

            this.setVisible(false);
        }

    }

}