Getting error "Your InputStream was neither an OLE2 stream, nor an OOXML stream" when created file through apache POI

Question

I am trying to check if my excel file already exists. If it doesn't exists, I want to create a new one and if it exists I will delete it and create a new one. I wrote following program but I am getting error at line - workbook= WorkbookFactory.create(instream);

The error is-> java.lang.IllegalArgumentException: Your InputStream was neither an OLE2 stream, nor an OOXML stream at org.apache.poi.ss.usermodel.WorkbookFactory.create(WorkbookFactory.java:89) at tryIng.main(tryIng.java:84)

Here is a program ->

 try {
                String filePath= "C:/Users/pritik/Desktop/t1.xlsx";
                File file = new File(filePath);
                filePath= file.getAbsolutePath(); 
                xlFile = new File(filePath);

                if(xlFile.exists() && !xlFile.isDirectory())
                    xlFile.delete(); //delete if file already exists.
                xlFile.createNewFile();

                inStream = new FileInputStream(xlFile);
                workbook =  WorkbookFactory.create(inStream);  // I get error at this line
                String sheetName="NewSheet";
                Sheet sheet = workbook.createSheet(sheetName);
                FileOutputStream fOut = new FileOutputStream(xlFile);

                int i,j;
                xRows = xTS.length;
                xCols = xTS[0].length;
                for(i =0;i<xRows;i++)
                {
                    row = sheet.createRow(i);
                    for(j=0;j<xCols;j++)
                    {
                        cell = row.createCell(j);
                        cell.setCellType(Cell.CELL_TYPE_STRING);
                        cell.setCellValue(xTS[i][j]);
                    } 
                } 
                workbook.write(fOut);
                fOut.flush();
                fOut.close();
        } catch (Exception e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        }   

Answer 1

Don't create an empty file and try to read it, that won't work. An empty zero byte file is not valid, and can't be loaded Instead, have POI create an new file for you, which you will write later.

Change the code:

if(xlFile.exists() && !xlFile.isDirectory())
    xlFile.delete(); //delete if file already exists.
xlFile.createNewFile();

inStream = new FileInputStream(xlFile);          
workbook =  WorkbookFactory.create(inStream);

To instead be:

if(xlFile.exists() && !xlFile.isDirectory())
    xlFile.delete(); //delete if file already exists.

if (xlFile.toString().endsWith(".xls") {
   workbook = new HSSFWorkbook();
} else {
   workbook = new XSSFWorkbook();
}

Also, if you do want to read an existing file, don't use a stream if you have a file! See this bit of the POI docs for why not.