Java - Apache POI - Read/Write .xlsx file - File getting corrupted and becomes empty

Question

I am using a Java program to read and write an existing .xlsx file(same file) but the file is getting corrupted, and the file size becomes zero bytes which is causing "org.apache.poi.EmptyFileException: The supplied file was empty (zero bytes long)”.

One more thing is - this is not happening consistently. The program is reading and writing to file properly most of the time but occurring once out of 10-15 runs. It would be helpful if anyone has a solution to this. BTW, am using Apache POI 3.13.

Read File Program:

public String getExcelData(String sheetName, int rowNum, int colNum){
    String retVal = null;
    try {
        FileInputStream fis = new FileInputStream("/Absolute/File/Path/Test-File.xlsx");
        Workbook wb = WorkbookFactory.create(fis);
        Sheet s = wb.getSheet(sheetName);
        Row r = s.getRow(rowNum);
        Cell c = r.getCell(colNum);
        retVal=(c.getStringCellValue());
    } catch (FileNotFoundException e) {
        // TODO Auto-generated catch block
        e.printStackTrace();
    } catch (InvalidFormatException e) {
        // TODO Auto-generated catch block
        e.printStackTrace();
    } catch (IOException e) {
        // TODO Auto-generated catch block
        e.printStackTrace();
    }
    return retVal;

Write File Program :

public void writeToExcel(String sheetName,int rowNum,int cellNum,String desc){
    try {
        FileInputStream fis = new FileInputStream("/Absolute/File/Path/Test-File.xlsx");
        Workbook wb = WorkbookFactory.create(fis);
        Sheet s = wb.getSheet(sheetName);
        Row r = s.getRow(rowNum);
        Cell c = r.createCell(cellNum);
        c.setCellValue(desc);
        FileOutputStream fos = new FileOutputStream("/Absolute/File/Path/Test-File.xlsx");
        wb.write(fos);
        fos.close();
    } catch (FileNotFoundException e) {
        // TODO Auto-generated catch block
        e.printStackTrace();
    } catch (InvalidFormatException e) {
        // TODO Auto-generated catch block
        e.printStackTrace();
    } catch (IOException e) {
        // TODO Auto-generated catch block
        e.printStackTrace();
    }
}

Error Trace:

Exception in thread "main" org.apache.poi.EmptyFileException: The supplied file was empty (zero bytes long)
at org.apache.poi.util.IOUtils.peekFirst8Bytes(IOUtils.java:55)
at org.apache.poi.ss.usermodel.WorkbookFactory.create(WorkbookFactory.java:201)
at org.apache.poi.ss.usermodel.WorkbookFactory.create(WorkbookFactory.java:168)
at ExcelLibrary.getExcelData(ExcelLibrary.java:139)
at Driver.main(Driver.java:82)

Answer 1

You are reading and writing to the same file at the same time. Try to first close FileInputStream fis before writing to FileOutputStream fos. Or use temporary file to write new result and then rename it to original one.

BTW. close automatically performs flush, so it don't has to be called separately.

Answer 2

you need to close the FileInputStream and FileOutputStream with org.apache.commons.io.IOUtils.closeQuietly(fos) and fis.