NoClassDefFoundError: UnsupportedFileFormatException while working with excel sheet using java -

i'm writing java program reads .xlsx file , give output in .csv format. code:

import java.io.file; import java.io.fileinputstream; import java.io.filenotfoundexception; import java.io.fileoutputstream; import java.io.ioexception; import java.io.outputstreamwriter; import java.io.writer; import java.text.simpledateformat;  import java.util.date; import java.util.iterator; import org.apache.poi.xssf.usermodel.xssfsheet; import org.apache.poi.xssf.usermodel.xssfworkbook; import org.apache.poi.ss.usermodel.cell;    import org.apache.poi.ss.usermodel.dateutil; import org.apache.poi.ss.usermodel.row;  public class xlsxtocsv {      public static void main(string[] args) {          long starttime = system.currenttimemillis();          file inputfile = new file("c:\\inputfile.xlsx");         file outputfile = new file("c:\\outputfile.csv");          xlsx(inputfile, outputfile);          long stoptime = system.currenttimemillis();         long elapsedtime = stoptime - starttime;          system.out.println(elapsedtime);     }     private static void xlsx(file inputfile, file outputfile) {          //for storing data csv files         stringbuffer data = new stringbuffer();          try {              writer w = new outputstreamwriter(new fileoutputstream(outputfile), "utf-8");              // workbook object xls file             xssfworkbook workbook = new xssfworkbook(new fileinputstream(inputfile));              // first sheet workbook             xssfsheet sheet = workbook.getsheetat(0);             cell cell;             row row;              // 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();                      switch (cell.getcelltype())                      {                         case cell.cell_type_boolean:                             data.append(cell.getbooleancellvalue() + ",");                             break;                          case cell.cell_type_numeric:                             if(dateutil.iscelldateformatted(cell)) {                                 date date = cell.getdatecellvalue();                                 system.out.println(date.tostring());                                 simpledateformat sdf = new simpledateformat("dd-mm-yyyy");                                 string d = sdf.format(date);                                 system.out.println(d);                                 data.append(d + ",");                                }                             else if(cell.getnumericcellvalue() == (int)cell.getnumericcellvalue())                                 data.append((int)cell.getnumericcellvalue() + ",");                             else if(cell.getnumericcellvalue() == (long)cell.getnumericcellvalue())                                 data.append((long)cell.getnumericcellvalue() + ",");                             else                                 data.append(cell.getnumericcellvalue() + ",");                             break;                          case cell.cell_type_string:                                 data.append((cell.getstringcellvalue()) + ",");                                 break;                          case cell.cell_type_blank:                                 data.append("" + ",");                                 break;                          default:                                 data.append(cell + ",");                         }                          //data.append('\n');                  }                 data.append("\r\n");         }          w.write(data.tostring());         w.close();      } catch(filenotfoundexception e) {         e.printstacktrace();     } catch(ioexception e) {         e.printstacktrace();     } } 

}

however, i'm getting following error:

exception in thread "main" java.lang.noclassdeffounderror: org/apache/poi/unsupportedfileformatexception @ java.lang.classloader.defineclass1(native method) @ java.lang.classloader.defineclass(unknown source) @ java.security.secureclassloader.defineclass(unknown source) @ java.net.urlclassloader.defineclass(unknown source) @ java.net.urlclassloader.access$100(unknown source) @ java.net.urlclassloader$1.run(unknown source) @ java.net.urlclassloader$1.run(unknown source) @ java.security.accesscontroller.doprivileged(native method) @ java.net.urlclassloader.findclass(unknown source) @ java.lang.classloader.loadclass(unknown source) @ sun.misc.launcher$appclassloader.loadclass(unknown source) @ java.lang.classloader.loadclass(unknown source) @ xlsxtocsv.xlsxtocsv.xlsx(xlsxtocsv.java:47) @ xlsxtocsv.xlsxtocsv.main(xlsxtocsv.java:28) caused by: java.lang.classnotfoundexception: org.apache.poi.unsupportedfileformatexception @ java.net.urlclassloader$1.run(unknown source) @ java.net.urlclassloader$1.run(unknown source) @ java.security.accesscontroller.doprivileged(native method) @ java.net.urlclassloader.findclass(unknown source) @ java.lang.classloader.loadclass(unknown source) @ sun.misc.launcher$appclassloader.loadclass(unknown source) @ java.lang.classloader.loadclass(unknown source) ... 14 more 

i have included following jars:

• dom4j-1.6.jar
• poi-3.9.jar
• poi-ooxml-3.11.jar
• poi-ooxml-schemas-3.8-20120326.jar
• xmlbeans-2.3.0.jar

i've checked file format .xlsx , directory don't understand problem is.

how can remove error?

this covered in apache poi faq page:

can mix poi jars different versions?

no. not supported.

all poi jars in use must come same version. combination such poi-3.11.jar , poi-ooxml-3.9.jar not supported, , fail work in unpredictable ways.

you list using poi-3.9.jar , poi-ooxml-3.11.jar different versions, , won't work.

you need ensure poi jars come same version. i'd suggest grab latest poi release download page (3.12 of writing), , use consistent set of jars that