NotOLE2FileException: Invalid header signature; read 0x0000000000000000, expected 0xE11AB1A1E011CFD0

Question

What I want to do is ask the user if they want to create a new or select an existing Excel workbook. Selecting an existing file is no problem. However I get an error saying "Your file appears not to be a valid OLE2 document" as soon as I create a name for a new Excel file.

public void selectExcelFile() {
    String excelFileName = null;                                // the name/directory/address of the excel file created/selected
    FileInputStream excelFileIn = null;                         // allows us to connect to the Excel file so we can read it
    FileOutputStream excelFileOut = null;                       // allows us to connect to the Excel file so we can write to it
    ExcelFileUtility eUtil = new ExcelFileUtility();            // used open an excel file

    if(columnsQuery != null) {
        try {
            excelFileName = eUtil.getFile(FileExtensions.XLS); // file extension = ".xls"

            if(excelFileName != null) {
                excelFileIn = new FileInputStream(new File(excelFileName));
                workbook = new HSSFWorkbook(excelFileIn);

                exportColsToWorkbook(columnsQuery);

                excelFileOut = new FileOutputStream(excelFileName);
                workbook.write(excelFileOut);

                // close everything
                workbook.close();
                excelFileIn.close();
                excelFileOut.close();
            }
        }
        catch (IOException e) {
            e.printStackTrace();
        }
        catch (SQLException e) {
            e.printStackTrace();
        }

    }
}

And then:

public String getFile(String extension) {
    String result = null;

    if(extension != null) {
        int choice = askIfNewFile();

        if(choice == 0) { // yes, create new file
            result = createFile(extension);
        } 

        else { // no, select existing file
            result = getFileLocation();                 
        }
    }
    else {
        System.out.println("No file extension.");
    }
    return result;

}

public String createFile(String extension) throws IOException {
    String newFileName = "";
    File newFile = null;
    boolean isCreated = false;

    JFrame frame = new JFrame("Creating a New ." + extension + " File");
    String result = null;

    String dir = getFileDirectory();
    System.out.println("DIR: " + dir);

    if(dir != null) {
        while(newFileName.isEmpty() || newFileName == null) {
            // Used WorkbookUtil.createSafeSheetName to validate file name
            // Please replace if there is a better option
            newFileName = WorkbookUtil.createSafeSheetName(JOptionPane.showInputDialog(frame, "Enter new ." + extension + " file name:"));
        }

        newFile = new File(dir + "\\" + newFileName + "." + extension);
        System.out.println(newFile.toString());

        try {
            isCreated = newFile.createNewFile();

            if(isCreated) {
                result = newFile.getAbsolutePath();
            }
            else {
                System.out.println("File already exists.");
            }
        }
        catch(IOException ioe) {
            System.out.println(ioe);
        }
    }
    return result;
}

public String getFileLocation() {
    String result = null;
    JFileChooser pickFile = new JFileChooser();

    if (pickFile.showOpenDialog(null) == JFileChooser.APPROVE_OPTION) {
        try {
            result = pickFile.getSelectedFile().getCanonicalPath();
        } catch (IOException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        }

        // check if file exists
    }
    System.out.println("File location: " + result);

    return result;
}

public String getFileDirectory() {
    String result = null;

    JFileChooser pickFile = new JFileChooser();

    pickFile.setDialogTitle("Choose Folder");
    pickFile.setFileSelectionMode(JFileChooser.DIRECTORIES_ONLY);
    pickFile.setAcceptAllFileFilterUsed(false);

    if (pickFile.showOpenDialog(null) == JFileChooser.APPROVE_OPTION) {
        result = pickFile.getSelectedFile().toString();
    }
    else {
        System.out.println("No Selection ");
    }

    return result;
}

Here is the error I get:

org.apache.poi.poifs.filesystem.NotOLE2FileException: Invalid header signature; read 0x0000000000000000, expected 0xE11AB1A1E011CFD0 - Your file appears not to be a valid OLE2 document
at org.apache.poi.poifs.storage.HeaderBlock.<init>(HeaderBlock.java:162)
at org.apache.poi.poifs.storage.HeaderBlock.<init>(HeaderBlock.java:112)
at org.apache.poi.poifs.filesystem.NPOIFSFileSystem.<init>(NPOIFSFileSystem.java:300)
at org.apache.poi.hssf.usermodel.HSSFWorkbook.<init>(HSSFWorkbook.java:400)
at org.apache.poi.hssf.usermodel.HSSFWorkbook.<init>(HSSFWorkbook.java:381)
at mhhls.him.dbtoexcel.program.DBtoExcel.selectExcelFile(DBtoExcel.java:159)
at mhhls.him.dbtoexcel.program.DBtoExcel.exportToExcel(DBtoExcel.java:422)
at mhhls.him.dbtoexcel.ui.main.DBtoExcelWindow$7.actionPerformed(DBtoExcelWindow.java:183)
at javax.swing.AbstractButton.fireActionPerformed(Unknown Source)
at javax.swing.AbstractButton$Handler.actionPerformed(Unknown Source)
at javax.swing.DefaultButtonModel.fireActionPerformed(Unknown Source)
at javax.swing.DefaultButtonModel.setPressed(Unknown Source)
at javax.swing.plaf.basic.BasicButtonListener.mouseReleased(Unknown Source)
at java.awt.Component.processMouseEvent(Unknown Source)
at javax.swing.JComponent.processMouseEvent(Unknown Source)
at java.awt.Component.processEvent(Unknown Source)
at java.awt.Container.processEvent(Unknown Source)
at java.awt.Component.dispatchEventImpl(Unknown Source)
at java.awt.Container.dispatchEventImpl(Unknown Source)
at java.awt.Component.dispatchEvent(Unknown Source)
at java.awt.LightweightDispatcher.retargetMouseEvent(Unknown Source)
at java.awt.LightweightDispatcher.processMouseEvent(Unknown Source)
at java.awt.LightweightDispatcher.dispatchEvent(Unknown Source)
at java.awt.Container.dispatchEventImpl(Unknown Source)
at java.awt.Window.dispatchEventImpl(Unknown Source)
at java.awt.Component.dispatchEvent(Unknown Source)
at java.awt.EventQueue.dispatchEventImpl(Unknown Source)
at java.awt.EventQueue.access$500(Unknown Source)
at java.awt.EventQueue$3.run(Unknown Source)
at java.awt.EventQueue$3.run(Unknown Source)
at java.security.AccessController.doPrivileged(Native Method)
at java.security.ProtectionDomain$JavaSecurityAccessImpl.doIntersectionPrivilege(Unknown Source)
at java.security.ProtectionDomain$JavaSecurityAccessImpl.doIntersectionPrivilege(Unknown Source)
at java.awt.EventQueue$4.run(Unknown Source)
at java.awt.EventQueue$4.run(Unknown Source)
at java.security.AccessController.doPrivileged(Native Method)
at java.security.ProtectionDomain$JavaSecurityAccessImpl.doIntersectionPrivilege(Unknown Source)
at java.awt.EventQueue.dispatchEvent(Unknown Source)
at java.awt.EventDispatchThread.pumpOneEventForFilters(Unknown Source)
at java.awt.EventDispatchThread.pumpEventsForFilter(Unknown Source)
at java.awt.EventDispatchThread.pumpEventsForHierarchy(Unknown Source)
at java.awt.EventDispatchThread.pumpEvents(Unknown Source)
at java.awt.EventDispatchThread.pumpEvents(Unknown Source)
at java.awt.EventDispatchThread.run(Unknown Source)

EDITED: I changed the selectExcelFile() method into this:

public void selectExcelFile() {
    String excelFileName = null;                                // the name/directory/address of the excel file created/selected
    FileInputStream excelFileIn = null;                         // allows us to connect to the Excel file so we can read it
    FileOutputStream excelFileOut = null;                       // allows us to connect to the Excel file so we can write to it
    ExcelFileUtility eUtil = new ExcelFileUtility();            // used open an excel file
    File newFile = null;

    if(columnsQuery != null) {
        try {
            excelFileName = eUtil.getFile(FileExtensions.XLS);

            if(excelFileName != null) {

                newFile = new File(excelFileName);

                if(newFile.exists()) {
                    try {
                        workbook =  WorkbookFactory.create(newFile);
                    } catch (EncryptedDocumentException | InvalidFormatException e) {
                        // TODO Auto-generated catch block
                        e.printStackTrace();
                    }
                }
                else {
                   if (newFile.getName().endsWith(".xls")) {
                       workbook = new HSSFWorkbook();
                   }
                   else if (newFile.getName().endsWith(".xlsx")) {
                       workbook = new XSSFWorkbook();
                   }
                   else {
                       throw new IllegalArgumentException("Must be .xls or .xlsx");
                   }
                }

                excelFileIn = new FileInputStream(newFile);
                exportColsToWorkbook(columnsQuery);

                excelFileOut = new FileOutputStream(newFile);
                workbook.write(excelFileOut);

                // close everything
                workbook.close();
                excelFileIn.close();
                excelFileOut.close();
            }
        }
        catch (IOException e) {
            e.printStackTrace();
        }
        catch (SQLException e) {
            e.printStackTrace();
        }

    }
}

Writing the workbook on the Excel file worksheet supposedly worked (did not get any errors), but when I opened the Excel file to check, I suddenly get this:

I click ok, and it's just empty. No worksheets or workbook.

So that explains why I get this error the next time I run the program and try to write the workbook on the same Excel file.

Exception in thread "AWT-EventQueue-0" org.apache.poi.EmptyFileException: The supplied file was empty (zero bytes long)
at org.apache.poi.poifs.filesystem.NPOIFSFileSystem.<init>(NPOIFSFileSystem.java:216)
at org.apache.poi.poifs.filesystem.NPOIFSFileSystem.<init>(NPOIFSFileSystem.java:166)
at org.apache.poi.ss.usermodel.WorkbookFactory.create(WorkbookFactory.java:278)
at org.apache.poi.ss.usermodel.WorkbookFactory.create(WorkbookFactory.java:250)
at org.apache.poi.ss.usermodel.WorkbookFactory.create(WorkbookFactory.java:229)
at mhhls.him.dbtoexcel.program.DBtoExcel.selectExcelFile(DBtoExcel.java:205)
at mhhls.him.dbtoexcel.program.DBtoExcel.exportToExcel(DBtoExcel.java:487)
at mhhls.him.dbtoexcel.ui.main.DBtoExcelWindow$7.actionPerformed(DBtoExcelWindow.java:190)
at javax.swing.AbstractButton.fireActionPerformed(Unknown Source)
at javax.swing.AbstractButton$Handler.actionPerformed(Unknown Source)
at javax.swing.DefaultButtonModel.fireActionPerformed(Unknown Source)
at javax.swing.DefaultButtonModel.setPressed(Unknown Source)
at javax.swing.plaf.basic.BasicButtonListener.mouseReleased(Unknown Source)
at java.awt.Component.processMouseEvent(Unknown Source)
at javax.swing.JComponent.processMouseEvent(Unknown Source)
at java.awt.Component.processEvent(Unknown Source)
at java.awt.Container.processEvent(Unknown Source)
at java.awt.Component.dispatchEventImpl(Unknown Source)
at java.awt.Container.dispatchEventImpl(Unknown Source)
at java.awt.Component.dispatchEvent(Unknown Source)
at java.awt.LightweightDispatcher.retargetMouseEvent(Unknown Source)
at java.awt.LightweightDispatcher.processMouseEvent(Unknown Source)
at java.awt.LightweightDispatcher.dispatchEvent(Unknown Source)
at java.awt.Container.dispatchEventImpl(Unknown Source)
at java.awt.Window.dispatchEventImpl(Unknown Source)
at java.awt.Component.dispatchEvent(Unknown Source)
at java.awt.EventQueue.dispatchEventImpl(Unknown Source)
at java.awt.EventQueue.access$500(Unknown Source)
at java.awt.EventQueue$3.run(Unknown Source)
at java.awt.EventQueue$3.run(Unknown Source)
at java.security.AccessController.doPrivileged(Native Method)
at java.security.ProtectionDomain$JavaSecurityAccessImpl.doIntersectionPrivilege(Unknown Source)
at java.security.ProtectionDomain$JavaSecurityAccessImpl.doIntersectionPrivilege(Unknown Source)
at java.awt.EventQueue$4.run(Unknown Source)
at java.awt.EventQueue$4.run(Unknown Source)
at java.security.AccessController.doPrivileged(Native Method)
at java.security.ProtectionDomain$JavaSecurityAccessImpl.doIntersectionPrivilege(Unknown Source)
at java.awt.EventQueue.dispatchEvent(Unknown Source)
at java.awt.EventDispatchThread.pumpOneEventForFilters(Unknown Source)
at java.awt.EventDispatchThread.pumpEventsForFilter(Unknown Source)
at java.awt.EventDispatchThread.pumpEventsForHierarchy(Unknown Source)
at java.awt.EventDispatchThread.pumpEvents(Unknown Source)
at java.awt.EventDispatchThread.pumpEvents(Unknown Source)
at java.awt.EventDispatchThread.run(Unknown Source)

I just don't understand why it corrupts the Excel file whenever I try to write the workbook onto a new worksheet.

Solution

You seem to have missed some key lines of code. However, assuming you are currently doing something like:

File newFile = new File("output.xlsx");
if (!newFile.exists) { newFile.createNewFile(); }
Workbook wb = WorkbookFactory.create(newFile);

Then this will not work!

You may only use WorkbookFactory to load pre-existing Excel files. You cannot use WorkbookFactory to create a brand new, empty Workbook. Very much related, you also can't do new HSSFWorkbook(emptyStream) or new HSSFWorkbook(emptyFile), if creating a *SSFWorkbook from an InputStream or a File then that must exist and be populated.

Instead, if you want to create a brand new empty workbook, what you need to do is more like:

Workbook wb;
File newFile = new File("output.xlsx");
if (newFile.exists) { 
   // Load existing
   wb = WorkbookFactory.create(newFile);
} else {
   // What kind of file are they trying to ask for?
   // Add additional supported types here
   if (newFile.getName().endsWith(".xls")) {
      wb = new HSSFWorkbook();
   }
   else if (newFile.getName().endsWith(".xlsx")) {
      wb = new XSSFWorkbook();
   }
   else {
      throw new IllegalArgumentException("I don't know how to create that kind of new file");
   }
}

For brand new empty files, you need to decide what kind of file to create, then new the appropriate *SSFWorkbook instance for it with no stream/file passed in