I’m a junior software engineer. Currently, I am struggling to convert an excel file from xls to xlsx without losing formats/formulas. I need your advise. I have been trying a few solutions using POI, but the table format is messed up. Please advise.

I have tried a few solutions online, even reading the POI documentation, but it did not help.

public class conversion_to_xlsx {
    
    public static void main(String[] args) throws InvalidFormatException,
    IOException {

String inpFn = "C:\Users\user\JavaProjects\workspace\Sample2\src\excelFileGenerate6\report.xls"; 
String outFn = "C:\Users\user\JavaProjects\workspace\Sample2\src\excelFileGenerate6\converted_report.xlsx"; 

FileInputStream in = new FileInputStream(inpFn);
try {
    Workbook wbIn = new HSSFWorkbook(in);
    File outF = new File(outFn);
    if (outF.exists())
        outF.delete();

    Workbook wbOut = new XSSFWorkbook();
    int sheetCnt = wbIn.getNumberOfSheets();
    for (int i = 0; i < sheetCnt; i++) {
        Sheet sIn = wbIn.getSheetAt(i);
        //Sheet sOut = wbOut.getSheet(null);
        Sheet sOut = wbOut.createSheet(sIn.getSheetName());
        Iterator<Row> rowIt = sIn.rowIterator();
        while (rowIt.hasNext()) {
            Row rowIn = rowIt.next();
            Row rowOut = sOut.createRow(rowIn.getRowNum());

            Iterator<Cell> cellIt = rowIn.cellIterator();
            while (cellIt.hasNext()) {
                Cell cellIn = cellIt.next();
                Cell cellOut = rowOut.createCell(
                        cellIn.getColumnIndex(), cellIn.getCellType());

                switch (cellIn.getCellType()) {
                case Cell.CELL_TYPE_BLANK:
                    break;

                case Cell.CELL_TYPE_BOOLEAN:
                    cellOut.setCellValue(cellIn.getBooleanCellValue());
                    break;

                case Cell.CELL_TYPE_ERROR:
                    cellOut.setCellValue(cellIn.getErrorCellValue());
                    break;

                case Cell.CELL_TYPE_FORMULA:
                    cellOut.setCellFormula(cellIn.getCellFormula());
                    break;

                case Cell.CELL_TYPE_NUMERIC:
                    cellOut.setCellValue(cellIn.getNumericCellValue());
                    break;

                case Cell.CELL_TYPE_STRING:
                    cellOut.setCellValue(cellIn.getStringCellValue());
                    break;
                }

                {
                    CellStyle styleIn = cellIn.getCellStyle();
                    CellStyle styleOut = cellOut.getCellStyle();
                    styleOut.setDataFormat(styleIn.getDataFormat());
                }
                cellOut.setCellComment(cellIn.getCellComment());

                // HSSFCellStyle cannot be cast to XSSFCellStyle
                // cellOut.setCellStyle(cellIn.getCellStyle());
            }
        }
    }
    FileOutputStream out = new FileOutputStream(outF);
    try {
        wbOut.write(out);
    } finally {
        out.close();
    }
} finally {
    in.close();
}
}
}