com的java NullPointerException。洛瓦吉。文本文件添加（要素e）

Question

我不确定这个错误消息实际上指向什么。要清楚的是，我知道什么是NullPointerException，但我无法弄清楚什么是不应该为null的。有人知道是什么原因导致此错误为空吗

谢谢

com.lowagie.text.DocumentException: java.lang.NullPointerException
    at com.lowagie.text.pdf.PdfDocument.add(Unknown Source)
    at com.lowagie.text.Document.add(Unknown Source)
...
Caused by: java.lang.NullPointerException
    at com.lowagie.text.pdf.PdfPTable.getRowHeight(Unknown Source)
    at com.lowagie.text.pdf.PdfPTable.calculateHeights(Unknown Source)
    at com.lowagie.text.pdf.PdfPTable.setTotalWidth(Unknown Source)
    at com.lowagie.text.pdf.ColumnText.goComposite(Unknown Source)
    at com.lowagie.text.pdf.ColumnText.go(Unknown Source)
    at com.lowagie.text.pdf.PdfPCell.getMaxHeight(Unknown Source)
    at com.lowagie.text.pdf.PdfPRow.calculateHeights(Unknown Source)
    at com.lowagie.text.pdf.PdfPRow.getMaxHeights(Unknown Source)
    at com.lowagie.text.pdf.PdfPTable.getRowHeight(Unknown Source)
    at com.lowagie.text.pdf.PdfPTable.calculateHeights(Unknown Source)
    at com.lowagie.text.pdf.PdfPTable.setTotalWidth(Unknown Source)
    at com.lowagie.text.pdf.ColumnText.goComposite(Unknown Source)
    at com.lowagie.text.pdf.ColumnText.go(Unknown Source)
    at com.lowagie.text.pdf.ColumnText.go(Unknown Source)
    at com.lowagie.text.pdf.PdfDocument.addPTable(Unknown Source)
    ... 97 more

有关守则：

    this.getDocument().open();
    Element body = this.getBody();
    System.out.println(body);
    System.out.println(this.getDocument().toString());
    this.getDocument().add(body);//it errors out here!
    this.getDocument().close();

调试语句返回：

com.lowagie.text.pdf.PdfPTable@1fa0c8f
com.lowagie.text.Document@14eb497

Answer 1

我得到了完全相同的错误和堆栈跟踪，并通过切换到OpenPDF解决了这个问题

OpenPDF基于iText 4，并有一些额外的错误修复和NPE修复。 OpenPDF正在积极维护

https://github.com/LibrePDF/OpenPDF