java - Error catching and File IO -

i have assignment need write while loop code block contains try­catch statement. try block retrieves each line input file, , invokes isvalid method created check if format correct, passing line file. if there no more lines parse, runprogram set false, while loop terminates. catch block catch exception made. far have

  public static void main(string[] args)   {      file file;      scanner inputfile;      string filename;       scanner scan = new scanner(file);      filename = scan.nextline();       boolean runprogram = true;      while(runprogram)      {         try         {            // loop check each line of file            // invoke isvalid            // check if it's last line in file, , end program if         }         catch(bankaccountexception e)         {            system.out.println("account exception. wish quit? y/n");            string quit = scan.nextline();            if(quit.equals("y"))               runprogram = false;            else               runprogram = true;         }      }   } 

i have no idea how open file, check next line, use isvalid method (which stringtokenizer checks correct format), , closes when reaches end of file.

here isvalid method:

   private static boolean isvalid(string accountline) throws bankaccountexception    {       stringtokenizer strtok = new stringtokenizer(accountline, ";");       boolean valid = true;       if(strtok.counttokens() == 2)       {          if(strtok.nexttoken().length() == 10)          {             if(!strtok.nexttoken().matches(".*[0-9].*"))             {                valid = true;             }          }       }       else          valid = false;       return valid;    } 

i have question above method. if call .nexttoken() twice, right in expecting first iteration deal first token, , second deal second? or both check first token?

just started.

try {   bufferedreader reader = new bufferedreader(new filereader(new file("/path/to/file")));   string currline;   while ((currline = reader.readline()) != null) { // returns null @ eof       if (!isvalid(currline)) throw new bankaccountexception();   } } catch (bankaccountexception e) {   // same } {     reader.close(); }