java - com.lowagie.text.Document.add(Element e) 的 NullPointerException

Question

我不太确定这个错误消息实际上指向什么。需要明确的是，我知道 NullPointerException 是什么，但我无法弄清楚什么是不应该的 null。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

有问题的代码:

    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 解决了问题。

OpenPDF 基于 iText 4，并具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