form_radio: Example code of Early Access iText

using System;
using iTextSharp.text;
using iTextSharp.text.pdf;
using System.IO;
public class form_radio
{
    
    
    [STAThread]
    public static void  Main(string[] args)
    {
        Document document = new Document(PageSize.A4, 50, 50, 50, 50);
        try
        {
            // creation of the different writers
            PdfWriter writer = PdfWriter.GetInstance(document, new FileStream(@"e:\java\form_radio.Pdf", FileMode.Create));
            document.Open();
            PdfContentByte cb = writer.DirectContent;
            cb.MoveTo(0, 0);
            PdfFormField radio = PdfFormField.CreateRadioButton(writer, true);
            PdfAppearance tpOff = cb.CreateAppearance(20, 20);
            PdfAppearance tpOn = cb.CreateAppearance(20, 20);
            
            tpOff.Circle(10, 10, 9);
            tpOff.Stroke();
            
            tpOn.Circle(10, 10, 9);
            tpOn.Stroke();
            tpOn.Circle(10, 10, 3);
            tpOn.FillStroke();
            
            radio.FieldName=("CreditCard");
            radio.ValueAsName=("MasterCard");
            
            PdfFormField radio1 = PdfFormField.CreateEmpty(writer);
            radio1.SetWidget(new Rectangle(100, 700, 120, 720), PdfAnnotation.HIGHLIGHT_INVERT);
            radio1.AppearanceState=("MasterCard");
            radio1.SetAppearance(PdfAnnotation.APPEARANCE_NORMAL, "Off", tpOff);
            radio1.SetAppearance(PdfAnnotation.APPEARANCE_NORMAL, "MasterCard", tpOn);
            radio.AddKid(radio1);
            
            PdfFormField radio2 = PdfFormField.CreateEmpty(writer);
            radio2.SetWidget(new Rectangle(100, 660, 120, 680), PdfAnnotation.HIGHLIGHT_INVERT);
            radio2.AppearanceState=("Off");
            radio2.SetAppearance(PdfAnnotation.APPEARANCE_NORMAL, "Off", tpOff);
            radio2.SetAppearance(PdfAnnotation.APPEARANCE_NORMAL, "Visa", tpOn);
            radio.AddKid(radio2);
            
            PdfFormField radio3 = PdfFormField.CreateEmpty(writer);
            radio3.SetWidget(new Rectangle(100, 620, 120, 640), PdfAnnotation.HIGHLIGHT_INVERT);
            radio3.AppearanceState=("Off");
            radio3.SetAppearance(PdfAnnotation.APPEARANCE_NORMAL, "Off", tpOff);
            radio3.SetAppearance(PdfAnnotation.APPEARANCE_NORMAL, "American", tpOn);
            radio.AddKid(radio3);
            
            writer.AddAnnotation(radio);
            document.Close();
            System.Console.Out.WriteLine("FIM.");
        }
        catch (System.Exception de)
        {
            System.Console.Error.WriteLine(de.Message);
        }
    }
}