Java - Error al conectar con MySQL

package trabajofinal3;

import java.sql.Connection;

import java.sql.ResultSet;

import java.sql.SQLException;

import java.sql.Statement;

import javax.swing.JOptionPane;

/**

 *

 * @author Darmask

 */

public class Login extends javax.swing.JFrame {

    //Instancio la clase Postgres

    private Conexion objMysql = new Conexion();

    public Login() {

        initComponents();

    }

    /**

     * This method is called from within the constructor to initialize the form.

     * WARNING: Do NOT modify this code. The content of this method is always

     * regenerated by the Form Editor.

     */

    @SuppressWarnings("unchecked")

    // <editor-fold defaultstate="collapsed" desc="Generated Code">

    private void initComponents() {

        lblSesion = new javax.swing.JLabel();

        lblUsuario = new javax.swing.JLabel();

        lblContraseña = new javax.swing.JLabel();

        txtNombre = new javax.swing.JTextField();

        btnIniciar = new javax.swing.JButton();

        txtPassword = new javax.swing.JPasswordField();

        txtUsuario = new javax.swing.JLabel();

        jMenuBar1 = new javax.swing.JMenuBar();

        jMenu1 = new javax.swing.JMenu();

        mnuSalir = new javax.swing.JMenuItem();

        setDefaultCloseOperation(javax.swing.WindowConstants.EXIT_ON_CLOSE);

        setTitle("Inicio Sesion");

        setBackground(new java.awt.Color(255, 0, 0));

        getContentPane().setLayout(new org.netbeans.lib.awtextra.AbsoluteLayout());

        lblSesion.setFont(new java.awt.Font("FreeMono", 1, 18)); // NOI18N

        lblSesion.setForeground(new java.awt.Color(255, 0, 0));

        lblSesion.setText("Inicio De Sesion");

        getContentPane().add(lblSesion, new org.netbeans.lib.awtextra.AbsoluteConstraints(130, 20, -1, -1));

        lblUsuario.setFont(new java.awt.Font("DialogInput", 1, 14)); // NOI18N

        lblUsuario.setForeground(new java.awt.Color(255, 255, 255));

        lblUsuario.setText("Usuario :");

        getContentPane().add(lblUsuario, new org.netbeans.lib.awtextra.AbsoluteConstraints(80, 80, -1, -1));

        lblContraseña.setFont(new java.awt.Font("DialogInput", 1, 14)); // NOI18N

        lblContraseña.setForeground(new java.awt.Color(255, 255, 255));

        lblContraseña.setText("Contraseña :");

        getContentPane().add(lblContraseña, new org.netbeans.lib.awtextra.AbsoluteConstraints(80, 150, -1, -1));

        getContentPane().add(txtNombre, new org.netbeans.lib.awtextra.AbsoluteConstraints(230, 80, 110, -1));

        btnIniciar.setIcon(new javax.swing.ImageIcon(getClass().getResource("/imagen/icono1.png.png"))); // NOI18N

        btnIniciar.setText("Iniciar");

        btnIniciar.addActionListener(new java.awt.event.ActionListener() {

            public void actionPerformed(java.awt.event.ActionEvent evt) {

                btnIniciarActionPerformed(evt);

            }

        });

        getContentPane().add(btnIniciar, new org.netbeans.lib.awtextra.AbsoluteConstraints(170, 220, 70, 30));

        getContentPane().add(txtPassword, new org.netbeans.lib.awtextra.AbsoluteConstraints(230, 160, 110, -1));

        txtUsuario.setIcon(new javax.swing.ImageIcon(getClass().getResource("/imagen/fondo.jpg"))); // NOI18N

        getContentPane().add(txtUsuario, new org.netbeans.lib.awtextra.AbsoluteConstraints(0, 6, 443, 288));

        jMenu1.setText("Archivo");

        mnuSalir.setText("Salir");

        mnuSalir.addActionListener(new java.awt.event.ActionListener() {

            public void actionPerformed(java.awt.event.ActionEvent evt) {

                mnuSalirActionPerformed(evt);

            }

        });

        jMenu1.add(mnuSalir);

        jMenuBar1.add(jMenu1);

        setJMenuBar(jMenuBar1);

        pack();

    }// </editor-fold>

    private void mnuSalirActionPerformed(java.awt.event.ActionEvent evt) {

        System.exit(0);

    }

    private void btnIniciarActionPerformed(java.awt.event.ActionEvent evt) {

        String usuario = txtNombre.getText();

        String password = txtPassword.getText();

        //VAlidacion de campos vacios

        if(txtNombre.getText().equals("")){

            JOptionPane.showMessageDialog(null,"Debe de Ingresar el Usuario");

            txtUsuario.requestFocus();

            return;

        }

       if(txtPassword.getText().equals("")){

            JOptionPane.showMessageDialog(null, "Debe de Ingresar la Contraseña");

            txtPassword.requestFocus();

            return;

        }

       else{

           try{

               login(usuario , password);

           }catch(SQLException ex){

               JOptionPane.showMessageDialog(null, ex);

           }

       }

    }

    public void login(String usuario , String password) throws SQLException{

        String SQL;

        String tipoUsuario="";

        Conexion con = new Conexion();

        Connection cnn = con.getConnection();

        SQL="SELECT * FROM usuarios WHERE  usuario ='"+usuario+"' AND pass ='"+password+"'";

        Statement st = cnn.createStatement();

        ResultSet rs = st.executeQuery(SQL);

        while(rs.next()){

            tipoUsuario = rs.getString("tipoUsuario");

        }

        if(tipoUsuario.equals("administrador")){

            ReporteVentas obj = new ReporteVentas();

            obj.setVisible(true);

            this.dispose();

        }

        if(tipoUsuario.equals("supervisor")){

            Supervisor obj = new Supervisor();

            obj.setVisible(true);

            this.dispose();

        }

       txtNombre.setText("");

       txtPassword.setText("");

       txtNombre.requestFocus();

    }

    /**

     * @param args the command line arguments

     */

    public static void main(String args[]) {

        java.awt.EventQueue.invokeLater(new Runnable() {

            public void run() {

                new Login().setVisible(true);

            }

        });

    }

    // Variables declaration - do not modify

    private javax.swing.JButton btnIniciar;

    private javax.swing.JMenu jMenu1;

    private javax.swing.JMenuBar jMenuBar1;

    private javax.swing.JLabel lblContraseña;

    private javax.swing.JLabel lblSesion;

    private javax.swing.JLabel lblUsuario;

    private javax.swing.JMenuItem mnuSalir;

    private javax.swing.JTextField txtNombre;

    public javax.swing.JPasswordField txtPassword;

    private javax.swing.JLabel txtUsuario;

    // End of variables declaration

}

try {

        Conexion con = new Conexion();

        Connection cnn = con.getConnection();

        SQL="SELECT * FROM usuarios WHERE  usuario ='"+usuario+"' AND pass ='"+password+"'";

        Statement st = cnn.createStatement();

        ResultSet rs = st.executeQuery(SQL);

        while(rs.next()){

            tipoUsuario = rs.getString("tipoUsuario");

        }

        if(tipoUsuario.equals("administrador")){

            ReporteVentas obj = new ReporteVentas();

            obj.setVisible(true);

            this.dispose();

        }

        if(tipoUsuario.equals("supervisor")){

            Supervisor obj = new Supervisor();

            obj.setVisible(true);

            this.dispose();

        }

       txtNombre.setText("");

       txtPassword.setText("");

       txtNombre.requestFocus();

} catch(SQLException e) {

System.out.println("El error es: "  + e.getCause());

}