java - Merge PDF with FDF output only PDF -

i have pdf , fdf file , want merge them single pdf. .pdf has no fields, these included in .fdf file, contents of fields also.

i have several solutions found, these works when fields stored in pdf.

i use itext java.

does have demo code how can solve problem? thank you!

here's code works when fields present in pdf

pdfreader pdfreader = new pdfreader(pdfinpath);    pdfstamper stamp = new pdfstamper(pdfreader, new fileoutputstream(pdfoutpath));    fdfreader fdfreader = new fdfreader(fdfinpath);    acrofields form = stamp.getacrofields();    form.setfields(fdfreader);    stamp.close();