reading xlsx and import it

Question

I am trying to create a class to read a XLSX file when I upload it to a website.
I have the code to upload the file to the server. The file can be uploaded but it can't capture the data from the excel.
May I know how do I solve or modify this code such that the data is being able to be seen on the web?
I know there's some other duplicate questions out there but after trying, those answers can't seem to work for me.
If I remove the line public static void... , then I will get this error: Package should contain a content type part [M1.13]

public HashMap getConstructJXLList_xlsx(UploadedFile File, int Sheetindex) {
    String _LOC = "[PageCodeBase: getConstructJXLList_xlsx]";

    HashMap _m = new HashMap();
    return _m;
}

    //InputStream _is = null;

    public static void main(String[] args)
        {
            try {
            FileInputStream input = new FileInputStream(new File("C:\\Users\\admin\\Desktop\\Load_AcctCntr_Template.xlsx"));
            org.apache.poi.ss.usermodel.Workbook wb = WorkbookFactory.create(input);
            org.apache.poi.ss.usermodel.Sheet s = wb.getSheetAt(0);

            Iterator<Row> rows = s.rowIterator();

                    while (rows.hasNext())
                    {
                        Row row = rows.next();
                        Iterator cells = row.cellIterator();
                        while (cells.hasNext())
                        {
                            XSSFCell cell = (XSSFCell) cells.next();

                            if (cell.getCellType() == XSSFCell.CELL_TYPE_STRING)
                            {
                                System.out.print(cell.getStringCellValue() + "t");
                            }
                            else if(cell.getCellType() == XSSFCell.CELL_TYPE_NUMERIC)
                            {
                                System.out.print(cell.getNumericCellValue() + "t");
                            }
                            else if(cell.CELL_TYPE_BLANK==cell.getCellType()) 
                                System.out.print( "BLANK " ); 
                            else 
                                System.out.print("Unknown cell type");
                        }
                input.close();
            }
                }
            catch (Exception e)
            {
                e.printStackTrace();
            }
}

If I just run the main method from above, this is the output:
0000002b SystemOut O [RedirectLogin: requiredRights]1.0en1102.xhtml
0000002b SystemOut O [En1102: doEn1102_command_readfileAction]1.0
0000002b SystemOut O [En1102: onPageLoadBegin]1.0
it seems that the server did not even run through this code above..

I can just download the excel template on the website and it will be saved on my desktop. The file will contain the title header and I am able to key in whatever data I want in the cells.

Answer 1

To read xlsx files, you should use:

import org.apache.poi.ss.usermodel.Row;
import org.apache.poi.xssf.usermodel.XSSFCell;
import org.apache.poi.xssf.usermodel.XSSFRow;
import org.apache.poi.xssf.usermodel.XSSFSheet;
import org.apache.poi.xssf.usermodel.XSSFWorkbook;

XSSFWorkbook wb;
XSSFSheet sheet;
XSSFRow row;
XSSFCell cell;

FileInputStream input = new FileInputStream(new File("C:\\Users\\admin\\Desktop\\Load_AcctCntr_Template.xlsx"));
wb = new XSSFWorkbook(input );