How to automate PDF form-filling in Java

Please take a look at the chapter about interactive forms in the free ebook The Best iText Questions on StackOverflow. It bundles the answers to questions such as:

• How to fill out a pdf file programatically?
• How can I flatten a XFA PDF Form using iTextSharp?
• Checking off pdf checkbox with itextsharp
• How to continue field output on a second page?
• finding out required fields to fill in pdf file
• and so on...

Or you can watch this video where I explain how to use forms for reporting step by step.

See for instance:

public 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();
    fields.setField("name", "CALIFORNIA");
    fields.setField("abbr", "CA");
    fields.setField("capital", "Sacramento");
    fields.setField("city", "Los Angeles");
    fields.setField("population", "36,961,664");
    fields.setField("surface", "163,707");
    fields.setField("timezone1", "PT (UTC-8)");
    fields.setField("timezone2", "-");
    fields.setField("dst", "YES");
    stamper.setFormFlattening(true);
    stamper.close();
    reader.close();
}

You can easily merge data into PDF's fields using the FDF(Form Data Format) technology.

Adobe provides a library to do that : Acrobat Forms Data Format (FDF) Toolkit

Also Apache PDFBox can be used to do that.