ExceptionConverter:io。IOException:文档没有页面。我使用iText

when i execute the below code

当我执行下面的代码。

File f = new File("c:/sample.pdf");
PdfWriter.getInstance(document, new FileOutputStream(f));
document.open();
System.out.println("opening the document..");
PdfPTable headerTable=new PdfPTable(9);
PdfPCell cellValue = new PdfPCell(new Paragraph("Header 1"));
cellValue.setColspan(1);
headerTable.addCell(cellValue);
cellValue = new PdfPCell(new Paragraph("Header 2"));
headerTable.addCell(cellValue);
cellValue = new PdfPCell(new Paragraph("Header 3"));
headerTable.addCell(cellValue);
cellValue = new PdfPCell(new Paragraph("Header 4"));
headerTable.addCell(cellValue);

PdfPTable subHeaderTable = new PdfPTable(3);
PdfPCell subHeadingCell = new PdfPCell(new Paragraph("Header 5"));
subHeadingCell.setColspan(3);
subHeaderTable.addCell(subHeadingCell);
subHeaderTable.addCell("Sub heading 1");
subHeaderTable.addCell("Sub heading 2"); 
subHeaderTable.addCell("Sub heading 3");

headerTable.addCell(subHeaderTable);

document.add(headerTable);
document.close();
F