Код

class OutDoc
{
    OutDoc() throws FileNotFoundException, IOException, InvalidFormatException
    {
        File fil1=new File(FileSelect.patchin);
        File fil2=new File("C:\\Users\\Капитошка\\Desktop\\nullfile.docx");
        Files.copy(fil1.toPath(), fil2.toPath());
        try{
        FileInputStream strr=new FileInputStream(FileSelect.patchin);
        final XWPFDocument doc = new XWPFDocument(strr);
        XWPFParagraph p1 = doc.createParagraph();
        XWPFRun r1 = p1.createRun();
        textField.getField();
        r1.setText(textField.finaltxt);
        final FileOutputStream out = new FileOutputStream(FileSelect.patchin);
        doc.write(out);
        out.close();}
        catch(Exception e)
        {
            FileInputStream strr=new FileInputStream(FileSelect.patchin);
            final HWPFDocument doc = new HWPFDocument(strr);
            Range range = doc.getRange();
            textField.getField();
            range.insertAfter(textField.finaltxt);
            final FileOutputStream out = new FileOutputStream(FileSelect.patchin);
            doc.write(out);
            out.close();
        }
    }
}