Problem with updating method in Database

I have this method save in a class that controls frame events:

    if(e.getSource()== estMostrar.getBtnModificar()){

        String nombre= estMostrar.getTxtNombre().getText();
        String materia= estMostrar.getTxtMatricula().getText();
        String nota= estMostrar.getTxtNota().getText();

        this.estDAO.actualizar(new Estudiante(nombre, materia, Integer.parseInt(nota)));
        this.ListarTabla(estAdmin.getTablaEstudiante());

        this.LimpiarCampos();
        this.estMostrar.dispose();
    }

The method that introduces the data to be saved is the estDAO.update :

this.estDAO.actualizar(new Estudiante(nombre, materia, Integer.parseInt(nota)));

What this does is that it sends the data as parameters to the DAO method that handles the query:

    public void actualizar(Estudiante e) {
    Connection con= null;
    PreparedStatement pstm= null;

        try {
            con= dbcon.conectar();

            String sql= "UPDATE notas SET nombre= ?, matricula= ?, nota= ?";
            pstm= con.prepareStatement(sql);

        pstm.setString(1, e.getNombre());
        pstm.setString(2, e.getMatricula());
        pstm.setInt(3, e.getNota());

        } catch (SQLException ex) {
            JOptionPane.showMessageDialog(null, "Error al conectar a la BD");
        }finally{
            dbcon.desconectar(con);
        }
}

But when checking the Database the object that I modified is still the same, could you tell me if there is something wrong in the code or how can I solve the problem, thanks in advance.

By order of the teacher I can not modify the update method, since they are part of a interface and he does not want that interface to change; finally I chose to modify it according to their recommendations, I have left the modify method like this:

    if(e.getSource()== estMostrar.getBtnModificar()){

        int fila= estAdmin.getTablaEstudiante().getSelectedRow();

        int id= Integer.parseInt(estAdmin.getTablaEstudiante().getValueAt(fila, 0).toString());

        String nombre= estMostrar.getTxtNombre().getText();
        String materia= estMostrar.getTxtMatricula().getText();
        String nota= estMostrar.getTxtNota().getText();

        this.estDAO.actualizar(new Estudiante(nombre, materia, Integer.parseInt(nota)), id);
        this.ListarTabla(estAdmin.getTablaEstudiante());

        this.LimpiarCampos();
        this.estMostrar.dispose();
    }

However, now the method gives me an exception NumberFormatException , I try to select an object from a JTable to modify it and when I press the getBtnModify button, the method gives this stackTrace :

Exception in thread "AWT-EventQueue-0" java.lang.NumberFormatException: For input string: "fklm"
at java.lang.NumberFormatException.forInputString(NumberFormatException.java:65)
at java.lang.Integer.parseInt(Integer.java:580)
at java.lang.Integer.parseInt(Integer.java:615)
at comm.estudiante.dao.controlador.ControladorEstudiante.actionPerformed(ControladorEstudiante.java:220)
at javax.swing.AbstractButton.fireActionPerformed(AbstractButton.java:2022)
at javax.swing.AbstractButton$Handler.actionPerformed(AbstractButton.java:2348)
at javax.swing.DefaultButtonModel.fireActionPerformed(DefaultButtonModel.java:402)
at javax.swing.DefaultButtonModel.setPressed(DefaultButtonModel.java:259)
at javax.swing.plaf.basic.BasicButtonListener.mouseReleased(BasicButtonListener.java:252)
at java.awt.Component.processMouseEvent(Component.java:6535)
at javax.swing.JComponent.processMouseEvent(JComponent.java:3324)
at java.awt.Component.processEvent(Component.java:6300)
at java.awt.Container.processEvent(Container.java:2236)
at java.awt.Component.dispatchEventImpl(Component.java:4891)
at java.awt.Container.dispatchEventImpl(Container.java:2294)
at java.awt.Component.dispatchEvent(Component.java:4713)
at java.awt.LightweightDispatcher.retargetMouseEvent(Container.java:4888)
at java.awt.LightweightDispatcher.processMouseEvent(Container.java:4525)
at java.awt.LightweightDispatcher.dispatchEvent(Container.java:4466)
at java.awt.Container.dispatchEventImpl(Container.java:2280)
at java.awt.Window.dispatchEventImpl(Window.java:2750)
at java.awt.Component.dispatchEvent(Component.java:4713)
at java.awt.EventQueue.dispatchEventImpl(EventQueue.java:758)
at java.awt.EventQueue.access$500(EventQueue.java:97)
at java.awt.EventQueue$3.run(EventQueue.java:709)
at java.awt.EventQueue$3.run(EventQueue.java:703)
at java.security.AccessController.doPrivileged(Native Method)
at java.security.ProtectionDomain$JavaSecurityAccessImpl.doIntersectionPrivilege(ProtectionDomain.java:76)
at java.security.ProtectionDomain$JavaSecurityAccessImpl.doIntersectionPrivilege(ProtectionDomain.java:86)
at java.awt.EventQueue$4.run(EventQueue.java:731)
at java.awt.EventQueue$4.run(EventQueue.java:729)
at java.security.AccessController.doPrivileged(Native Method)
at java.security.ProtectionDomain$JavaSecurityAccessImpl.doIntersectionPrivilege(ProtectionDomain.java:76)
at java.awt.EventQueue.dispatchEvent(EventQueue.java:728)
at java.awt.EventDispatchThread.pumpOneEventForFilters(EventDispatchThread.java:201)
at java.awt.EventDispatchThread.pumpEventsForFilter(EventDispatchThread.java:116)
at java.awt.EventDispatchThread.pumpEventsForHierarchy(EventDispatchThread.java:105)
at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:101)
at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:93)
at java.awt.EventDispatchThread.run(EventDispatchThread.java:82)

row 220 is this:

int id= Integer.parseInt(estAdmin.getTablaEstudiante().getValueAt(fila, 0).toString());