update connectivity

   private void jButton3ActionPerformed(java.awt.event.ActionEvent evt) {
        // TODO add your handling code here:
        String admno= jTextField1.getText();
    String rollno= jTextField2.getText();
    String name = jTextField3.getText();
    String address =jTextField4.getText();
    String marks=jTextField5.getText();


    try

    {
        Class.forName("java.sql.Driver");
            Connection con = DriverManager.getConnection("jdbc:mysql://localhost:3306/school","root","1234");
            Statement stmt =  con.createStatement();
            String query= "Update student set rollno='"+rollno+"',name='"+name+"',address='"+address+"', marks='"+marks+"'  where admno="+admno+";";
;

                 JOptionPane.showMessageDialog(this,query);
            stmt.executeUpdate(query);


    }

    catch(Exception e)
    {
        JOptionPane.showMessageDialog(this,e.getMessage());
    }