How to check if radio button in PDF is checked or not?

I am trying to learn how to manipulate PDFs with the iText library. I am able to retrieve the value or state of a checkbox.

For example:

public static void manipulatePdf(String src, String dest) throws DocumentException, IOException {

    PdfReader reader    = new PdfReader(src);
    PdfStamper stamper  = new PdfStamper(reader, new FileOutputStream(dest));

    AcroFields fields   = stamper.getAcroFields();

    String[] checkbox   = fields.getAppearanceStates("cb1"); //cb1 is the name of the checkbox in my test PDF
    for(int i = 0; i < checkbox.length; i++) {
        System.out.println(checkbox[i]);
    }

    System.out.println(fields.getField("cb1"));    

Output is: Yes Off Yes

My question here is how to check if a radio button is checked. I could not find any solutions for this.

I tried the same code like:

System.out.println(fields.getField("Choice1")); //Choice1 is the name of the first radio button in my first group "group1"