Getting data from a JDialog

Hi everybody, I'm doing an app where I need to get a value from a
variable of another JDialog.

My MainFrame call the class SelectClient, where SelectClient has a
JTable with all data. when user double click over the table it supose
to return the data of the selected cell.
I tried like this :

//main.java

public void actionPerformed(ActionEvent e) {
        if(e.getSource() == btCad) {
                   SelectClient tmp = new SelectClient(this);
                  while(tmp.running) {
                 try {
                      wait();
                     } catch ( InterruptedException e1) { }

                   }

            String data = tmp.data;
            tmp.dispose();

//SelectClient.java
class SelectClient extends JDialog ....
  public void mouseClicked(MouseEvent e) {
        if (e.getSource() == tableClients) {
            if (e.getClickCount() == 2) {
                   data = tableModel.getPrimaryKey(1);
                           running = false;
                           notifyAll();
                           }
                   }
                 }