How to find out which fields are required?

I'm starting with new functionality in my android application which will help to fill certain PDF forms. I found out that the best solution will be to use iText library. I can read file, and read AcroFields from a document but is there any possibility to find out that specific field is marked as required?

Posted on StackOverflow on Feb 17, 2013 by weedget

Please take a look at section 13.3.4 of "iText in Action - Second Edition", entitled "AcroForms revisited". Listing 13.15 shows a code snippet from the InspectForm example that checks whether or not a field is a password or a multi-line field.

With some minor changes, you can adapt that example to check for required fields:

for (Map.Entry entry : fields.entrySet()) {
    out.write(entry.getKey());
    item = entry.getValue();
    dict = item.getMerged(0);
    flags = dict.getAsNumber(PdfName.FF);
    if (flags != null && (flags.intValue() & BaseField.REQUIRED) > 0)
        out.write(" -> required\n");
}