String options[] = {"Red", "Green", "Blue"};
PdfFormField field = PdfFormField.createCombo(writer, true, options, 0);
field.setWidget(new Rectangle(100, 700, 180, 720), PdfAnnotation.HIGHLIGHT_INVERT);
field.setFieldName("ACombo");
field.setValueAsString("Red");
writer.addAnnotation(field);
}
catch(DocumentException de) {
System.err.println(de.getMessage());
}