How to add new sheets to existing excel workbook using apache POI?

Question

I am trying to write List data into multiple excel sheet in one work book. like for first list, the code will create new workbook and create new sheet for list[1], for second list it will create new sheet in existing workbook and so on. so i wrote below code. but it doesnt work and i am able to see only first sheet for list[1]. can someone help me to provide any alternate resolutions?

the below code i have written

    ArrayList<List<String>> tempresultdata=this.getSummaryList();
    HSSFWorkbook workbook = new HSSFWorkbook();
    String fileName="Path\\To\\XLS";
    File file = new File(fileName);
    FileOutputStream out;           
    if(!file.exists()) // This will create new workbook with new sheet if it doesnt exists{

                HSSFSheet mySheet = workbook.createSheet(sheetname);
                writeExcel(mySheet,tempresultdata);
    } else // This add new sheet to above created workbook {
            try {
                HSSFWorkbook myWorkBook = (HSSFWorkbook) WorkbookFactory.create(file);
                workbook=myWorkBook;
                HSSFSheet mySheet = (HSSFSheet) workbook.createSheet(sheetname);
                writeExcel(mySheet,tempresultdata);                 
            } catch (InvalidFormatException e) {
                // TODO Auto-generated catch block
                e.printStackTrace();
            } catch (IOException e) {
                // TODO Auto-generated catch block
                e.printStackTrace();
            }
    }   
    try{
        out = new FileOutputStream(fileName,true);
        workbook.write(out);
        out.close();
        }catch(Exception e){ 
            e.printStackTrace();
        }

Thanks, Priyank Shah

Answer 1

If file does not exist then this code creates new file and also creates sample sheet1 but if file exists then it adds new sheet to existing excel file.

    HSSFWorkbook workbook = null;
    File file = new File(context.getExternalFilesDir(null), "Sample.xls");
    FileOutputStream fileOut = new FileOutputStream(file);

    if (file.exists()) {
        try {
            workbook = (HSSFWorkbook)WorkbookFactory.create(file);
        } catch (InvalidFormatException e) {
            e.printStackTrace();
        }
        HSSFSheet sheet = workbook.createSheet("Sample sheet2");
    }
    else{
        workbook = new HSSFWorkbook();
        HSSFSheet sheet = workbook.createSheet("Sample sheet1");
    }
    workbook.write(fileOut);
    fileOut.close();

Answer 2

Looks like you are only writing out the sheet not the workbook