Hi all,
Im starting to program in java with sql.
The problem im having is that when im trying to complete a combo box with data from a table in sql i get this error:
"null error in cargarComboProvincias()" when i run the program, and i cant find the error in the code. :S
id appreciate if any1 helps me with it :D

import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.ResultSet;
import java.sql.Statement;
import javax.swing.JOptionPane;


public class Proveedores extends javax.swing.JFrame
{
    Connection cnn;
    ConexionesBaseDeDatos conexiones = new ConexionesBaseDeDatos();

    
    public Proveedores() {
        initComponents();
    }

    @SuppressWarnings("unchecked")
    // <editor-fold defaultstate="collapsed" desc="Generated Code">
    private void initComponents() {

        jLabel1 = new javax.swing.JLabel();
        jLabel2 = new javax.swing.JLabel();
        jLabel3 = new javax.swing.JLabel();
        jLabel4 = new javax.swing.JLabel();
        jLabel5 = new javax.swing.JLabel();
        txtNombreProveedor = new javax.swing.JTextField();
        txtDireccionProveedor = new javax.swing.JTextField();
        txtMailProveedor = new javax.swing.JTextField();
        cmbProvinciasProveedores = new javax.swing.JComboBox();
        btnCrearProveedor = new javax.swing.JButton();
        btnModificarProveedor = new javax.swing.JButton();
        btnDesabilitarProveedor = new javax.swing.JButton();
        txtTelefonoProveedor = new javax.swing.JFormattedTextField();
        jScrollPane1 = new javax.swing.JScrollPane();
        listProveedores = new javax.swing.JList();
        btnAceptar = new javax.swing.JButton();
        btnGuardarCambios = new javax.swing.JButton();
        btnDesabilitar = new javax.swing.JButton();
        btnCancelar = new javax.swing.JButton();
        jMenuBar1 = new javax.swing.JMenuBar();
        jMenu1 = new javax.swing.JMenu();
        jMenuItem1 = new javax.swing.JMenuItem();
        jMenuItem2 = new javax.swing.JMenuItem();
        jMenuItem3 = new javax.swing.JMenuItem();
        jMenuItem4 = new javax.swing.JMenuItem();
        jMenuItem5 = new javax.swing.JMenuItem();
        jMenuItem6 = new javax.swing.JMenuItem();
        jMenuItem7 = new javax.swing.JMenuItem();
        jMenuItem10 = new javax.swing.JMenuItem();
        jMenuItem11 = new javax.swing.JMenuItem();
        jMenu3 = new javax.swing.JMenu();
        jMenuItem9 = new javax.swing.JMenuItem();
        jMenu4 = new javax.swing.JMenu();
        jMenuItem8 = new javax.swing.JMenuItem();
        jMenu2 = new javax.swing.JMenu();
        jMenuItem12 = new javax.swing.JMenuItem();
        jMenu5 = new javax.swing.JMenu();

        setDefaultCloseOperation(javax.swing.WindowConstants.EXIT_ON_CLOSE);
        addWindowListener(new java.awt.event.WindowAdapter() {
            public void windowActivated(java.awt.event.WindowEvent evt) {
                formWindowActivated(evt);
            }
        });

        jLabel1.setText("Nombre");

        jLabel2.setText("Teléfono");

        jLabel3.setText("Dirección");

        jLabel4.setText("Mail");

        jLabel5.setText("Provincia");

        btnCrearProveedor.setText("Crear Proveedor");

        btnModificarProveedor.setText("Modificar Proveedor");

        btnDesabilitarProveedor.setText("Deshabilitar Proveedor");

        txtTelefonoProveedor.setCursor(new java.awt.Cursor(java.awt.Cursor.TEXT_CURSOR));

        listProveedores.setEnabled(false);
        listProveedores.setVisibleRowCount(13);
        jScrollPane1.setViewportView(listProveedores);

        btnAceptar.setText("Aceptar");

        btnGuardarCambios.setText("Guardar Cambios");
        btnGuardarCambios.setEnabled(false);

        btnDesabilitar.setText("Desabilitar");
        btnDesabilitar.setEnabled(false);

        btnCancelar.setText("Cancelar");

        jMenu1.setText("File");

        jMenuItem1.setText("Proveedores");
        jMenu1.add(jMenuItem1);

        jMenuItem2.setText("Clientes");
        jMenu1.add(jMenuItem2);

        jMenuItem3.setText("Modelos");
        jMenu1.add(jMenuItem3);

        jMenuItem4.setText("Eventos");
        jMenu1.add(jMenuItem4);

        jMenuItem5.setText("Subastas");
        jMenu1.add(jMenuItem5);

        jMenuItem6.setText("Compras");
        jMenu1.add(jMenuItem6);

        jMenuItem7.setText("Ventas");
        jMenu1.add(jMenuItem7);

        jMenuItem10.setText("Colecciones");
        jMenu1.add(jMenuItem10);

        jMenuItem11.setText("Lineas");
        jMenu1.add(jMenuItem11);

        jMenu3.setText("Productos");

        jMenuItem9.setText("Tipos de productos");
        jMenu3.add(jMenuItem9);

        jMenu1.add(jMenu3);

        jMenu4.setText("Insumos");

        jMenuItem8.setText("Tipos de insumos");
        jMenu4.add(jMenuItem8);

        jMenu1.add(jMenu4);

        jMenuBar1.add(jMenu1);

        jMenu2.setText("Ayuda");

        jMenuItem12.setText("Acerca de...");
        jMenu2.add(jMenuItem12);

        jMenuBar1.add(jMenu2);

        jMenu5.setText("Salir");
        jMenuBar1.add(jMenu5);

        setJMenuBar(jMenuBar1);

        javax.swing.GroupLayout layout = new javax.swing.GroupLayout(getContentPane());
        getContentPane().setLayout(layout);
        layout.setHorizontalGroup(
            layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
            .addGroup(layout.createSequentialGroup()
                .addGap(40, 40, 40)
                .addComponent(btnCrearProveedor)
                .addGap(97, 97, 97)
                .addComponent(btnModificarProveedor)
                .addGap(104, 104, 104)
                .addComponent(btnDesabilitarProveedor)
                .addContainerGap(64, Short.MAX_VALUE))
            .addGroup(layout.createSequentialGroup()
                .addGap(67, 67, 67)
                .addComponent(btnAceptar)
                .addGap(52, 52, 52)
                .addComponent(btnCancelar)
                .addPreferredGap(javax.swing.LayoutStyle.ComponentPlacement.RELATED, 92, Short.MAX_VALUE)
                .addComponent(btnGuardarCambios)
                .addGap(62, 62, 62)
                .addComponent(btnDesabilitar)
                .addGap(71, 71, 71))
            .addGroup(layout.createSequentialGroup()
                .addGap(22, 22, 22)
                .addGroup(layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
                    .addGroup(layout.createSequentialGroup()
                        .addComponent(jLabel5)
                        .addGap(18, 18, 18)
                        .addComponent(cmbProvinciasProveedores, javax.swing.GroupLayout.PREFERRED_SIZE, 120, javax.swing.GroupLayout.PREFERRED_SIZE))
                    .addGroup(layout.createParallelGroup(javax.swing.GroupLayout.Alignment.TRAILING, false)
                        .addGroup(layout.createSequentialGroup()
                            .addComponent(jLabel2)
                            .addGap(18, 18, 18)
                            .addComponent(txtTelefonoProveedor))
                        .addGroup(javax.swing.GroupLayout.Alignment.LEADING, layout.createSequentialGroup()
                            .addComponent(jLabel4)
                            .addGap(42, 42, 42)
                            .addComponent(txtMailProveedor, javax.swing.GroupLayout.PREFERRED_SIZE, 120, javax.swing.GroupLayout.PREFERRED_SIZE)))
                    .addGroup(layout.createSequentialGroup()
                        .addGroup(layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
                            .addComponent(jLabel3)
                            .addComponent(jLabel1))
                        .addGap(18, 18, 18)
                        .addGroup(layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING, false)
                            .addComponent(txtNombreProveedor)
                            .addComponent(txtDireccionProveedor, javax.swing.GroupLayout.DEFAULT_SIZE, 117, Short.MAX_VALUE))))
                .addPreferredGap(javax.swing.LayoutStyle.ComponentPlacement.RELATED, 137, Short.MAX_VALUE)
                .addComponent(jScrollPane1, javax.swing.GroupLayout.PREFERRED_SIZE, 312, javax.swing.GroupLayout.PREFERRED_SIZE)
                .addGap(36, 36, 36))
        );
        layout.setVerticalGroup(
            layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
            .addGroup(layout.createSequentialGroup()
                .addGap(20, 20, 20)
                .addGroup(layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
                    .addComponent(btnCrearProveedor, javax.swing.GroupLayout.PREFERRED_SIZE, 34, javax.swing.GroupLayout.PREFERRED_SIZE)
                    .addComponent(btnModificarProveedor, javax.swing.GroupLayout.PREFERRED_SIZE, 34, javax.swing.GroupLayout.PREFERRED_SIZE)
                    .addGroup(layout.createSequentialGroup()
                        .addGap(1, 1, 1)
                        .addComponent(btnDesabilitarProveedor, javax.swing.GroupLayout.PREFERRED_SIZE, 32, javax.swing.GroupLayout.PREFERRED_SIZE)))
                .addGroup(layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
                    .addGroup(layout.createSequentialGroup()
                        .addGap(50, 50, 50)
                        .addGroup(layout.createParallelGroup(javax.swing.GroupLayout.Alignment.BASELINE)
                            .addComponent(jLabel1)
                            .addComponent(txtNombreProveedor, javax.swing.GroupLayout.PREFERRED_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.PREFERRED_SIZE))
                        .addGroup(layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
                            .addGroup(layout.createSequentialGroup()
                                .addGap(27, 27, 27)
                                .addComponent(jLabel3))
                            .addGroup(layout.createSequentialGroup()
                                .addGap(22, 22, 22)
                                .addComponent(txtDireccionProveedor, javax.swing.GroupLayout.PREFERRED_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.PREFERRED_SIZE)))
                        .addGap(20, 20, 20)
                        .addGroup(layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
                            .addGroup(layout.createSequentialGroup()
                                .addGap(3, 3, 3)
                                .addComponent(jLabel5))
                            .addComponent(cmbProvinciasProveedores, javax.swing.GroupLayout.PREFERRED_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.PREFERRED_SIZE))
                        .addGap(18, 18, 18)
                        .addGroup(layout.createParallelGroup(javax.swing.GroupLayout.Alignment.BASELINE)
                            .addComponent(jLabel2)
                            .addComponent(txtTelefonoProveedor, javax.swing.GroupLayout.PREFERRED_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.PREFERRED_SIZE))
                        .addGap(21, 21, 21)
                        .addGroup(layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
                            .addGroup(layout.createSequentialGroup()
                                .addGap(3, 3, 3)
                                .addComponent(jLabel4))
                            .addComponent(txtMailProveedor, javax.swing.GroupLayout.PREFERRED_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.PREFERRED_SIZE))
                        .addGap(35, 35, 35))
                    .addGroup(javax.swing.GroupLayout.Alignment.TRAILING, layout.createSequentialGroup()
                        .addGap(36, 36, 36)
                        .addComponent(jScrollPane1, javax.swing.GroupLayout.DEFAULT_SIZE, 223, Short.MAX_VALUE)
                        .addGap(27, 27, 27)))
                .addGroup(layout.createParallelGroup(javax.swing.GroupLayout.Alignment.BASELINE)
                    .addComponent(btnDesabilitar)
                    .addComponent(btnAceptar)
                    .addComponent(btnCancelar)
                    .addComponent(btnGuardarCambios))
                .addGap(64, 64, 64))
        );

        pack();
    }// </editor-fold>

    private void formWindowActivated(java.awt.event.WindowEvent evt) {
        deshabilitarCampos();
        cargarComboProvincias();
    }

    public static void main() {
        java.awt.EventQueue.invokeLater(new Runnable() {
            public void run() {
                new Proveedores().setVisible(true);
            }
        });
    }

    // Variables declaration - do not modify
    private javax.swing.JButton btnAceptar;
    private javax.swing.JButton btnCancelar;
    private javax.swing.JButton btnCrearProveedor;
    private javax.swing.JButton btnDesabilitar;
    private javax.swing.JButton btnDesabilitarProveedor;
    private javax.swing.JButton btnGuardarCambios;
    private javax.swing.JButton btnModificarProveedor;
    private javax.swing.JComboBox cmbProvinciasProveedores;
    private javax.swing.JLabel jLabel1;
    private javax.swing.JLabel jLabel2;
    private javax.swing.JLabel jLabel3;
    private javax.swing.JLabel jLabel4;
    private javax.swing.JLabel jLabel5;
    private javax.swing.JMenu jMenu1;
    private javax.swing.JMenu jMenu2;
    private javax.swing.JMenu jMenu3;
    private javax.swing.JMenu jMenu4;
    private javax.swing.JMenu jMenu5;
    private javax.swing.JMenuBar jMenuBar1;
    private javax.swing.JMenuItem jMenuItem1;
    private javax.swing.JMenuItem jMenuItem10;
    private javax.swing.JMenuItem jMenuItem11;
    private javax.swing.JMenuItem jMenuItem12;
    private javax.swing.JMenuItem jMenuItem2;
    private javax.swing.JMenuItem jMenuItem3;
    private javax.swing.JMenuItem jMenuItem4;
    private javax.swing.JMenuItem jMenuItem5;
    private javax.swing.JMenuItem jMenuItem6;
    private javax.swing.JMenuItem jMenuItem7;
    private javax.swing.JMenuItem jMenuItem8;
    private javax.swing.JMenuItem jMenuItem9;
    private javax.swing.JScrollPane jScrollPane1;
    private javax.swing.JList listProveedores;
    private javax.swing.JTextField txtDireccionProveedor;
    private javax.swing.JTextField txtMailProveedor;
    private javax.swing.JTextField txtNombreProveedor;
    private javax.swing.JFormattedTextField txtTelefonoProveedor;
    // End of variables declaration


/*
-------------------------------------------------------------------------------------------------------------------------------
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 */

    private void deshabilitarCampos()
    {
        txtNombreProveedor.setEnabled(false);
        txtDireccionProveedor.setEnabled(false);
        txtMailProveedor.setEnabled(false);
        btnAceptar.setEnabled(false);
        btnCancelar.setEnabled(false);
        btnDesabilitar.setEnabled(false);
        btnGuardarCambios.setEnabled(false);
        cmbProvinciasProveedores.setEnabled(false);
        listProveedores.setEnabled(false);
    }

    private void habilitarCamposBtnCrearProveedor()
    {
        btnAceptar.setEnabled(true);
        btnCancelar.setEnabled(true);
        cmbProvinciasProveedores.setEnabled(true);
        listProveedores.setEnabled(true);
        txtDireccionProveedor.setEnabled(true);
        txtMailProveedor.setEnabled(true);
        txtNombreProveedor.setEnabled(true);
    }

    private void habilitarCamposBtnModificarProveedor()
    {
        btnAceptar.setEnabled(false);
        btnCancelar.setEnabled(true);
        cmbProvinciasProveedores.setEnabled(true);
        listProveedores.setEnabled(true);
        txtDireccionProveedor.setEnabled(true);
        txtMailProveedor.setEnabled(true);
        txtNombreProveedor.setEnabled(true);
        btnGuardarCambios.setEnabled(true);
        btnDesabilitarProveedor.setEnabled(false);
        btnDesabilitar.setEnabled(false);
        btnCrearProveedor.setEnabled(false);
    }

    private void limpiarCampos()
    {
        cmbProvinciasProveedores.setSelectedIndex(-1);
        txtDireccionProveedor.setText("");
        txtMailProveedor.setText("");
        txtNombreProveedor.setText("");
    }






/*
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*/
    public void habilitarbtnCrearProveedor()
    {
        btnAceptar.setEnabled(true);
        btnCancelar.setEnabled(true);
        cmbProvinciasProveedores.setEnabled(true);
        txtDireccionProveedor.setEnabled(true);
        txtMailProveedor.setEnabled(true);
        txtNombreProveedor.setEnabled(true);
        txtTelefonoProveedor.setEnabled(true);
    }

    
    private void cargarComboProvincias()
    {
       Statement sql;
       ResultSet datos;
       boolean seguir;
       Provincias provinciaActual;

       try
       {
           sql = cnn.createStatement();
           datos = sql.executeQuery("SELECT * FROM provincias WHERE id_provincia IS NOT NULL");
           seguir = datos.next();

           while (seguir)
           {
               provinciaActual = new Provincias();
               provinciaActual.setId_provincia(datos.getInt("id_provincia"));
               provinciaActual.setNombre_provincia(datos.getString("nombre_provincia"));

               provinciaActual.toString();
               cmbProvinciasProveedores.addItem(provinciaActual);
               seguir = datos.next();
          }
       }
       catch (Exception e)
       {
           JOptionPane.showMessageDialog(null,e.getMessage() + "error en cargarComboProvincias");
       }
    }
}

The "null error" (presumably null pointer error) also tells you the exact line number where it happened. Would you like to tell us, or do we have to guess?

No, it doesn't give me a line number :S. After closing the window, i get this:
"run:
BUILD SUCCESSFUL (total time: 1 minute 4 seconds)". I put the error as a pop-up window.

Either replace this line

JOptionPane.showMessageDialog(null,e.getMessage() + "error en cargarComboProvincias");

with

e.printStackTrace();

or add the stack trace before/after your dialog message.

You are suppressing most of the useful debugging information from the exception.

well, i just added that line to the code, and what i get is :

java.lang.NullPointerException
        at dolls.Proveedores.cargarComboProvincias(Proveedores.java:410)
        at dolls.Proveedores.formWindowActivated(Proveedores.java:265)
        at dolls.Proveedores.access$000(Proveedores.java:10)
        at dolls.Proveedores$1.windowActivated(Proveedores.java:65)
        at java.awt.AWTEventMulticaster.windowActivated(AWTEventMulticaster.java:372)
        at java.awt.Window.processWindowEvent(Window.java:1874)
        at javax.swing.JFrame.processWindowEvent(JFrame.java:279)
        at java.awt.Window.processEvent(Window.java:1820)
        at java.awt.Component.dispatchEventImpl(Component.java:4630)
        at java.awt.Container.dispatchEventImpl(Container.java:2099)
        at java.awt.Window.dispatchEventImpl(Window.java:2475)
        at java.awt.Component.dispatchEvent(Component.java:4460)
        at java.awt.KeyboardFocusManager.redispatchEvent(KeyboardFocusManager.java:1848)
        at java.awt.DefaultKeyboardFocusManager.typeAheadAssertions(DefaultKeyboardFocusManager.java:889)
        at java.awt.DefaultKeyboardFocusManager.dispatchEvent(DefaultKeyboardFocusManager.java:409)
        at java.awt.Component.dispatchEventImpl(Component.java:4502)
        at java.awt.Container.dispatchEventImpl(Container.java:2099)
        at java.awt.Window.dispatchEventImpl(Window.java:2475)
        at java.awt.Component.dispatchEvent(Component.java:4460)
        at java.awt.EventQueue.dispatchEvent(EventQueue.java:599)
        at java.awt.SentEvent.dispatch(SentEvent.java:55)
        at java.awt.DefaultKeyboardFocusManager$DefaultKeyboardFocusManagerSentEvent.dispatch(DefaultKeyboardFocusManager.java:183)
        at java.awt.DefaultKeyboardFocusManager.sendMessage(DefaultKeyboardFocusManager.java:210)
        at java.awt.DefaultKeyboardFocusManager.dispatchEvent(DefaultKeyboardFocusManager.java:286)
        at java.awt.Component.dispatchEventImpl(Component.java:4502)
        at java.awt.Container.dispatchEventImpl(Container.java:2099)
        at java.awt.Window.dispatchEventImpl(Window.java:2475)
        at java.awt.Component.dispatchEvent(Component.java:4460)
        at java.awt.EventQueue.dispatchEvent(EventQueue.java:599)
        at java.awt.SequencedEvent.dispatch(SequencedEvent.java:101)
        at java.awt.EventQueue.dispatchEvent(EventQueue.java:597)
        at java.awt.EventDispatchThread.pumpOneEventForFilters(EventDispatchThread.java:269)
        at java.awt.EventDispatchThread.pumpEventsForFilter(EventDispatchThread.java:184)
        at java.awt.EventDispatchThread.pumpEventsForHierarchy(EventDispatchThread.java:174)
        at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:169)
        at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:161)
        at java.awt.EventDispatchThread.run(EventDispatchThread.java:122)
java.lang.NullPointerException
        at dolls.Proveedores.cargarComboProvincias(Proveedores.java:410)
        at dolls.Proveedores.formWindowActivated(Proveedores.java:265)
        at dolls.Proveedores.access$000(Proveedores.java:10)
        at dolls.Proveedores$1.windowActivated(Proveedores.java:65)
        at java.awt.AWTEventMulticaster.windowActivated(AWTEventMulticaster.java:372)
        at java.awt.Window.processWindowEvent(Window.java:1874)
        at javax.swing.JFrame.processWindowEvent(JFrame.java:279)
        at java.awt.Window.processEvent(Window.java:1820)
        at java.awt.Component.dispatchEventImpl(Component.java:4630)
        at java.awt.Container.dispatchEventImpl(Container.java:2099)
        at java.awt.Window.dispatchEventImpl(Window.java:2475)
        at java.awt.Component.dispatchEvent(Component.java:4460)
        at java.awt.KeyboardFocusManager.redispatchEvent(KeyboardFocusManager.java:1848)
        at java.awt.DefaultKeyboardFocusManager.typeAheadAssertions(DefaultKeyboardFocusManager.java:889)
        at java.awt.DefaultKeyboardFocusManager.dispatchEvent(DefaultKeyboardFocusManager.java:409)
        at java.awt.Component.dispatchEventImpl(Component.java:4502)
        at java.awt.Container.dispatchEventImpl(Container.java:2099)
        at java.awt.Window.dispatchEventImpl(Window.java:2475)
        at java.awt.Component.dispatchEvent(Component.java:4460)
        at java.awt.EventQueue.dispatchEvent(EventQueue.java:599)
        at java.awt.SentEvent.dispatch(SentEvent.java:55)
        at java.awt.DefaultKeyboardFocusManager$DefaultKeyboardFocusManagerSentEvent.dispatch(DefaultKeyboardFocusManager.java:183)
        at java.awt.DefaultKeyboardFocusManager.sendMessage(DefaultKeyboardFocusManager.java:210)
        at java.awt.DefaultKeyboardFocusManager.dispatchEvent(DefaultKeyboardFocusManager.java:286)
        at java.awt.Component.dispatchEventImpl(Component.java:4502)
        at java.awt.Container.dispatchEventImpl(Container.java:2099)
        at java.awt.Window.dispatchEventImpl(Window.java:2475)
        at java.awt.Component.dispatchEvent(Component.java:4460)
        at java.awt.EventQueue.dispatchEvent(EventQueue.java:599)
        at java.awt.SequencedEvent.dispatch(SequencedEvent.java:101)
        at java.awt.EventQueue.dispatchEvent(EventQueue.java:597)
        at java.awt.EventDispatchThread.pumpOneEventForFilters(EventDispatchThread.java:269)
        at java.awt.EventDispatchThread.pumpEventsForFilter(EventDispatchThread.java:184)
        at java.awt.EventDispatchThread.pumpEventsForHierarchy(EventDispatchThread.java:174)
        at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:169)
        at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:161)
        at java.awt.EventDispatchThread.run(EventDispatchThread.java:122)

those lines are the 410:

sql = cnn.createStatement();

and the 216

private void formWindowActivated(java.awt.event.WindowEvent evt) {
        deshabilitarCampos();
        cargarComboProvincias();
    }

when the procedure is called (cargarComboProvincias();)

So now you know that 'cnn' is null. The next step is to figure out why it's null.

commented: i love similair answerer, not joke +1 +9
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