private void btnLogInActionPerformed(java.awt.event.ActionEvent evt) {                                         
        String sessieId;
        
        try {
            sessieId = balie.logIn(tfAccount.getText(), new String(fldPassword.getPassword()));
            System.out.println("de sessie"+ sessieId);
            if (sessieId == null) {
                setMessage("Accountname and/or password not correct.");
            } else {
               //RemotePropertyListener l = new BankierSessieDialog(balie, sessieId);
                RemotePropertyListener l = new BankierSessieDialog();
                balie.addListener( l,sessieId);
                dispose();
            }
        } catch (Exception e1) {
           /....
}

public class BankierSessieDialog extends javax.swing.JFrame  implements
        RemotePropertyListener {

    private IRemoteBalie balie;
    private String sessieId;
    private RekeningKlantInfo rekeningKlantInfo;

    //remove this testing construct.
    public BankierSessieDialog() throws RemoteException{
     System.out.println("BankieSessieDialog constructor");
     UnicastRemoteObject.exportObject(this,0);  
    }
    //remove above
   
      public BankierSessieDialog(IRemoteBalie balie, String sessieId) throws RemoteException {
        initComponents();
        UnicastRemoteObject.exportObject(this,0);
        this.balie = balie;
        this.sessieId = sessieId;
      
        try {
            this.rekeningKlantInfo = balie.getRekeningKlantInfo(sessieId);
            //...gui inits..
            
            } catch (Exception exc) {
              // ...
              }