java - 使用Apache POI时出现空指针异常

我正在尝试使用Apache POI包编写一个Excel文件。这是代码片段:

String basePath = "/home/aman/Desktop";
String fileName = "result.xls";
File file = new File(basePath, fileName);   //File not null. checked.
OPCPackage pkg = OPCPackage.openOrCreate(file);  //pkg not null. checked.
Workbook wb = new XSSFWorkbook(pkg);   //GenerateReport.java:63

我收到以下错误:

Exception in thread "main" java.lang.NullPointerException
at org.apache.poi.POIXMLDocumentPart.read(POIXMLDocumentPart.java:382)
at org.apache.poi.POIXMLDocument.load(POIXMLDocument.java:155)
at org.apache.poi.xssf.usermodel.XSSFWorkbook.<init>(XSSFWorkbook.java:186)
at amazon.category.database.GenerateReport.generateExcel(GenerateReport.java:63)
at amazon.category.database.MerchantAdoptionStats.processAdoptionStats(MerchantAdoptionStats.java:197)
at amazon.category.database.MerchantAdoptionStats.main(MerchantAdoptionStats.java:386)

任何帮助表示赞赏。

最佳答案

我在教程站点上找到了此示例:
here
您可以尝试这种方法。

    Workbook wb = new HSSFWorkbook();
    //Workbook wb = new XSSFWorkbook();
    CreationHelper createHelper = wb.getCreationHelper();
    Sheet sheet = wb.createSheet("new sheet");

    // Create a row and put some cells in it. Rows are 0 based.
    Row row = sheet.createRow((short)0);
    // Create a cell and put a value in it.
    Cell cell = row.createCell(0);
    cell.setCellValue(1);

    // Or do it on one line.
    row.createCell(1).setCellValue(1.2);
    row.createCell(2).setCellValue(createHelper.createRichTextString("This is a string"));
    row.createCell(3).setCellValue(true);

    // Write the output to a file
    FileOutputStream fileOut = new FileOutputStream("workbook.xls");
    wb.write(fileOut);
    fileOut.close();