java - Excel to String xls/xlsx different result -

want compare excel files each other see if same or not. can choose excel files , read them. have 2 excel sheets same content 1 in .xls , on in .xlsx format. use following code read files (for xls hssfworkbook , on)

private string xlsx(file inputfile) {         string outputstring = "";          // storing data string         stringbuffer data = new stringbuffer();         try {             // workbook object xlsx file             xssfworkbook wbook = new xssfworkbook(new fileinputstream(inputfile));              // first sheet workbook             xssfsheet sheet = wbook.getsheetat(0);             row row;             cell cell;              // iterate through each rows first sheet             iterator<row> rowiterator = sheet.iterator();              while (rowiterator.hasnext()) {                 row = rowiterator.next();                  // each row, iterate through each columns                 iterator<cell> celliterator = row.celliterator();                 while (celliterator.hasnext()) {                      cell = celliterator.next();                      data.append(cell + ";");                 }                 data.append("\n");             }             system.out.println(data.tostring());             outputstring = data.tostring();             wbook.close();         } catch (exception ioe) {             ioe.printstacktrace();         }          return outputstring;     } 

in excel have blank cells - when read them xls data;;;;;data correct when same in xlsx data;data

somehow code skips empty cells?! how can fix problem? in advance

after more google research , trying different things found solution problem. iterator skips empty cells because have no value - null - in xls file seems not null - whatever

my code:

private string xlsx(file inputfile) {     string outputstring = "";     system.out.println("start");     // storing data string     stringbuffer data = new stringbuffer();     try {         // workbook object xlsx file         xssfworkbook wbook = new xssfworkbook(new fileinputstream(inputfile));          // first sheet workbook         xssfsheet sheet = wbook.getsheetat(0);        // decide rows process         int rowstart =  0;         int rowend =  sheet.getlastrownum()+1;          (int rownum = rowstart; rownum < rowend; rownum++) {            row r = sheet.getrow(rownum);             int lastcolumn = r.getlastcellnum();             (int cn = 0; cn < lastcolumn; cn++) {               cell c = r.getcell(cn);               if (c == null) {                  data.append("" + ";");               } else {                  data.append(c + ";");               }            }            data.append("\n");         }          system.out.println(data.tostring());         outputstring = data.tostring();         wbook.close();     } catch (exception ioe) {         ioe.printstacktrace();     }     system.out.println("end");     return outputstring; }