public autogen() {

          initComponents();
           //JComboBox g1 = new JComboBox();

          try{
    String url ="jdbc:sqlserver://localhost:1433;databaseName=class ";
    String use = "mali";
    String password = "12345";
    Connection con = DriverManager.getConnection(url,use,password);
    Statement st = con.createStatement ();
    ResultSet rs;

     String sq = "SELECT DISTINCT(grd) FROM addteacher";
    rs= st.executeQuery(sq);
    while(rs.next()){
    jComboBox3.addItem("--Select a Grade--");
    jComboBox3.addItem(rs.getString("grd"));
                      }

                }
       catch (Exception evt){

            }
          jComboBox3.addItemListener(new ItemListener(){
            public void itemStateChanged(ItemEvent e){
                if (e.getSource() == jComboBox3)
                jComboBox1.removeAllItems();
                {
                    if(!(jComboBox3.getSelectedItem() == null )){

                        try{
    String url ="jdbc:sqlserver://localhost:1433;databaseName=class ";
    String use = "mali";
    String password = "12345";
    Connection con = DriverManager.getConnection(url,use,password);
    Statement st = con.createStatement ();
    ResultSet rs;
        String p = jComboBox3.getSelectedItem().toString();
       String sq = "SELECT DISTINCT(sub) FROM addteacher WHERE grd= '" + p +"' ";
    rs= st.executeQuery(sq);
    while(rs.next()){
    jComboBox1.addItem("--Select a Subject--");
    jComboBox1.addItem(rs.getString("sub"));
                  }

                        }
   catch (Exception evt){

            }
                    }
                    else { }
                }  }});
              private void jButton1ActionPerformed(java.awt.event.ActionEvent evt) {


  JComboBox g1 = new JComboBox();
    setLayout(new FlowLayout());
    add(g1);

     pack();


}