iText html转pdf的空指针异常

Document document = new Document();
PdfWriter writer = PdfWriter.getInstance(document, new FileOutputStream(file));
document.open();
XMLWorkerHelper.getInstance().parseXHtml(writer, document, new FileInputStream(htmlName),
Charset.forName("UTF-8"));
document.close();

            以上代码,走到
             XMLWorkerHelper.getInstance().parseXHtml(writer, document, new FileInputStream(htmlName),
        Charset.forName("UTF-8"));
                    时报空指针异常,请问大神,错在哪里哈

调试下，看这一行上的document writer htmlName是否有null

估计XMLWorkerHelper.getInstance() 为null , 怎么都喜欢一句过的代码，我建议把上面的代码分成三行代码，很容易就是知道那里有问题了