How to create and save Excel file to DAM using java

I am trying to create one excel sheet and save it into DAM.I am able to create excel in DAM, but no data is there in that excel. I am using following codes to create it.

String filename = "updatedMetadata.xls";

    FileOutputStream fos = new FileOutputStream(filename);

    WritableWorkbook workbook = Workbook.createWorkbook(new File(filename));

    WritableSheet writableSheet = workbook.createSheet("Updated Metadata", 0);

    Label label = null;

    label = new Label(0, 0, "Header1");

    writableSheet.addCell(label);

    label = new Label(0, 1, "Header2");

    writableSheet.addCell(label);

    label = new Label(0, 2, "Header3");

    writableSheet.addCell(label);

    label = new Label(0, 3, "Header4");

    writableSheet.addCell(label);

    label = new Label(0, 4, "Header5");

    writableSheet.addCell(label);

    label = new Label(0, 5, "Header6");

    writableSheet.addCell(label);

    label = new Label(0, 6, "Header7");

    writableSheet.addCell(label);

    label = new Label(0, 7, "Header8");

    writableSheet.addCell(label);

    label = new Label(1, 0, "col val");

    writableSheet.addCell(label);

    label = new Label(1, 1, "col val");

    writableSheet.addCell(label);

    label = new Label(1, 2, "col val");

    writableSheet.addCell(label);

    label = new Label(1, 3, "col val");

    writableSheet.addCell(label);

    label = new Label(1, 4, "col val");

    writableSheet.addCell(label);

    label = new Label(1, 5, "col val");

    writableSheet.addCell(label);

    label = new Label(1, 6, "col val");

    writableSheet.addCell(label);

    label = new Label(1, 7, "col val");

    writableSheet.addCell(label);

    label = new Label(2, 0, "col val");

    writableSheet.addCell(label);

    label = new Label(2, 1, "col val");

    writableSheet.addCell(label);

    label = new Label(2, 2, "col val");

    writableSheet.addCell(label);

    label = new Label(2, 3, "col val");

    writableSheet.addCell(label);

    label = new Label(2, 4, "col val");

    writableSheet.addCell(label);

    label = new Label(2, 5, "col val");

    writableSheet.addCell(label);

    label = new Label(2, 6, "col val");

    writableSheet.addCell(label);

    label = new Label(2, 7, "col val");

    writableSheet.addCell(label);

    workbook.write();

    workbook.close();

    ResourceResolver resourceResolver = request.getResourceResolver();

    AssetManager manager = resourceResolver.adaptTo(AssetManager.class);

    InputStream is = this.getClass().getResourceAsStream("/content/dam/company/fileFolder/" + filename);

    Asset asset = manager.createAsset("/content/dam/company/fileFolder/" + filename, is, "application/vnd.ms-excel", true);

File is creating in this Path "/content/dam/company/fileFolder/"

File name is "updatedMetadata.xls"

Thanks in advance

Mahesh Narayanan