Excel file gets corrupted after launching an executable jar

I have an Eclipse project with the following code that uses Apache POI.

public static void main(String[] args){
    try{
        XSSFWorkbook sourceWorkbook = new XSSFWorkbook("input.xlsx");
        XSSFSheet sheet = sourceWorkbook.getSheetAt(0);
        // do stuff
        sourceWorkbook.close();         
    } catch (IOException e){
        e.printStackTrace();
    }
}

When I launch it from Eclipse, it works properly. Since I created the executable jar, when I use it, the Excel input file passes from 9 to 1 kB and it won’t open anymore.

[EDIT: since I was asked:

• the file is only read, I never write it.
• the version of apache POI is 3.15 ]

How can I fix it?

Answer

You could try the following option:

• create a FileInputStream to the workbook path
• do that in a try-with-resources statement
• close the workbook inside the try block

Maybe like this:

public static void main(String[] args) {
    String wbPath = "input.xlsx";
    // use an auto-closable resource stream 
    try (FileInputStream fis = new FileInputStream(wbPath)) {
        // then use that in order to open the workbook
        Workbook workbook = new XSSFWorkbook(fis);
        // then open the sheet
        Sheet sheet = workbook.getSheetAt(0);
        
        // and do stuff…
        
        // Having done stuff, close the workbook explicitly
        workbook.close();
        // and let the try with resources close the input stream
    } catch (FileNotFoundException e) {
        // do proper exception handling here
        throw new RuntimeException("file " + wbPath + " seems not to exist");
    } catch (IOException e) {
        // do proper exception handling here, too
        throw new RuntimeException("error during read or write operation");
    }
}

The RuntimeExceptions are just for making the code work and not just printing a stack trace there. As the comments say, you might want to do something better in the catch blocks.

As an alternative to new XSSFWorkbook(fis) you could use the WorkbookFactory in order to create(fis).