尝试写入已经存在的* .xlsx文件，导致NullPointerException

Question

following is my function

 public static void writeOutputExtraInfo(
        HueIfxModuleMasterStruct<OutputEngineIfxJobMasterStruct> 
    ifxModuleMasterStruct, String filePath)
        throws InvalidFormatException, IOException {
    File file = new File(filePath);
    //XSSFWorkbook workbook = (XSSFWorkbook)WorkbookFactory.create(file);
    XSSFWorkbook workbook = new XSSFWorkbook(file);
    writeOutputExtraBasicInfo(ifxModuleMasterStruct, workbook);
    FileOutputStream fileOutputStream = new FileOutputStream(new File(filePath));
    workbook.write(fileOutputStream);
    fileOutputStream.close();
    workbook.close();

}

I get the following error

org.apache.poi.POIXMLException: java.lang.NullPointerException
at org.apache.poi.POIXMLDocument.getProperties(POIXMLDocument.java:159) ~[poi-ooxml-3.13.jar:3.13]
at org.apache.poi.POIXMLDocument.write(POIXMLDocument.java:210) ~[poi-ooxml-3.13.jar:3.13]

can someone tell whats wrong with the code.

Answer 1

Can you try this way?

Workbook workbook = WorkbookFactory.create(new FileInputStream(filePath));

So, obtaining the Workbook instance from the FileInputStream.

Answer 2

There is a comment in the javadoc for the constructor of XSSFWorkbook:

Once you have finished working with the Workbook, you should close the package by calling POIXMLDocument.close(), to avoid leaving file handles open.

So my guess is that the exception is due to the fact that the file is open, not because it exists.