public class DijalogIznajmiFilm extends JDialog {

    private final JPanel contentPanel = new JPanel();
    private Korisnik korisnik;

    public static void main(String[] args) {
        try {
            DijalogIznajmiFilm dialog = new DijalogIznajmiFilm();
            dialog.setDefaultCloseOperation(JDialog.DISPOSE_ON_CLOSE);
            dialog.setVisible(true);
        } catch (Exception e) {
            e.printStackTrace();
        }
    }

    public DijalogIznajmiFilm() {
        setTitle("Iznajmljivanje filma");
        setBounds(100, 100, 450, 300);
        getContentPane().setLayout(new BorderLayout());
        contentPanel.setBorder(new EmptyBorder(5, 5, 5, 5));
        getContentPane().add(contentPanel, BorderLayout.CENTER);
        contentPanel.setLayout(null);

        Film[] filmovi = FilmController.getList();

        JList<Film>listaFilmova = new JList<Film>(filmovi);
        listaFilmova.setSelectionMode(ListSelectionModel.SINGLE_SELECTION);

        listaFilmova.setBounds(10, 57, 414, 160);
        contentPanel.add(listaFilmova);

        JLabel lblKorisnik = new JLabel();
        lblKorisnik.setHorizontalAlignment(SwingConstants.CENTER);
        /////////////// ovde puca i javlja null Pointer
        lblKorisnik.setText(korisnik.toString());
        ///////////////
        lblKorisnik.setFont(new Font("Tahoma", Font.PLAIN, 12));
        lblKorisnik.setBounds(10, 11, 414, 35);
        contentPanel.add(lblKorisnik);
        {
            JPanel buttonPane = new JPanel();
            buttonPane.setLayout(new FlowLayout(FlowLayout.RIGHT));
            getContentPane().add(buttonPane, BorderLayout.SOUTH);
            {
                JButton okButton = new JButton("Iznajmi");
                okButton.addActionListener(new ActionListener() {
                    public void actionPerformed(ActionEvent e) {
                        Film f = (Film) listaFilmova.getSelectedValue();
                        if (f == null)
                            JOptionPane.showMessageDialog(null, "Morate izabrati film");
                        else {

                        }
                    }
                });
                okButton.setActionCommand("OK");
                buttonPane.add(okButton);
                getRootPane().setDefaultButton(okButton);
            }
    }

    public void setKorisnik(Korisnik korisnik) {
        this.korisnik = korisnik;
    }
}