private void buttonList_Click(object sender, EventArgs e)
{
Employee emp = new Employee();
if (EmployeeValidation.isValidID(textboxEmployeeId) && EmployeeValidation.isValidName(textboxName))
{
emp.EmployeeID = Convert.ToInt32(textboxEmployeeId.Text);
emp.Name = textboxName.Text;
emp.PhoneNumber = maskedtextboxPhoneNumber.Text;
EmployeeDA.Add(emp);
ClearAll();
}
}