Count No_Of_Month in Between Two Month in java

 try
        {
           Class.forName("com.mysql.jdbc.Driver");
            java.sql.Connection con=DriverManager.getConnection("jdbc:mysql://localhost:3305/commity","root","root");
    String sql="select * from group1 where Group_Number='"+jTextField14.getText()+"'";
    java.sql.PreparedStatement pst=con.prepareStatement(sql);
    DefaultTableModel tm33 = (DefaultTableModel) maintable.getModel();
        tm33.setRowCount(0);
    ResultSet rs = pst.executeQuery(sql);
     int i=0;
  while(rs.next())
  {
Vector v2 = new Vector();
Calendar startCalendar = Calendar.getInstance();
startCalendar.setTime(rs.getDate(2));
Calendar endCalendar = Calendar.getInstance();
endCalendar.setTime(rs.getDate(3));

int diffYear = endCalendar.get(Calendar.YEAR) - startCalendar.get(Calendar.YEAR);
int diffMonth = diffYear * 12 + endCalendar.get(Calendar.MONTH) - startCalendar.get(Calendar.MONTH);
System.out.println(""+diffMonth);
v2.addElement(rs.getString(1));
   v2.addElement(rs.getDate(2));
   v2.addElement(rs.getDate(3));
   v2.addElement(rs.getDouble(4));
   v2.addElement(rs.getDouble(5));
   v2.addElement(rs.getInt(6));
   v2.addElement(diffMonth);
   tm33.addRow(v2);
  }
con.close();
pst.close();
        }
        catch(Exception e)
        {
            System.out.println(e);
            JOptionPane.showMessageDialog(null, e);
        }