java - I would like to add (insert) column numbers (from 1 to 1000) at first column in the .CSV file -

for example

my input.csv contains data this..

row_no ,user , actions

john , sql transaction

suman , transaction failed

ram , button pressed retrieve details

and looking for.. advance each 1 of have tried this

output.csv

row_no ,user , actions

1 ,john , sql transaction

2 ,suman , transaction failed

3 ,ram , button pressed retrieve details

please me

this have tried

public class mapwriter  {  public static void main(string[] args) throws ioexception {      csvmapreader mapreader = null;      icsvmapwriter mapwriter = null;      try        {          csvpreference prefs = csvpreference.standard_preference;          mapreader = new csvmapreader(new filereader("d:\\input.csv"), prefs);          mapwriter = new csvmapwriter(new filewriter("d:\\output.csv"), prefs);          // header used read original file          final string[] readheader = mapreader.getheader(true);          // header used write new file           // (same 'readheader', additional column)          final string[] writeheader = new string[readheader.length + 1];          system.arraycopy(readheader, 0, writeheader, 0, readheader.length);          final string timeheader = "   ";          writeheader[writeheader.length-1]= timeheader;          mapwriter.writeheader(writeheader);          int count=1;          map<string, string> row;          while( (row = mapreader.read(readheader)) != null ) {              // add column desired value          row.put(timeheader, string.valueof(count));          mapwriter.write(row, writeheader);              count++;           }       }     {         if( mapreader != null )         {             mapreader.close();         }          if( mapwriter != null )          {             mapwriter.close();         }     }  } 

}

as far can tell, you're trying use verifying csv parser on invalid data (e.g. row_no blank everywhere header in input file). i'm not if that's allowed parser, don't believe need parse file yet. example, stringtokenizer , scanner -

public static void main(string[] args) {     string inputfile = "c:/input.csv";     string outputfile = "c:/output.csv";     int linenumber = 0;                    // <-- keep line count.     scanner scanner = null;     printwriter pw = null;     try {         pw = new printwriter(outputfile);  // <-- output         file source = new file(inputfile);         scanner = new scanner(source);     // <-- input         while (scanner.hasnextline()) {             string line = scanner.nextline();             line = (line != null) ? line.trim() : "";             if (line.length() < 1) {                 continue;             }             // line 0 header.             if (linenumber != 0) {                 pw.print(linenumber);                 pw.print(", ");             }             int tokencount = 0;             stringtokenizer st = new stringtokenizer(line, ",");             while (st.hasmoretokens()) {                 string token = st.nexttoken();                 if (tokencount != 0) {                     pw.print(", ");                 }                 pw.print(token.trim());                 tokencount++;             }             pw.println();             linenumber++;         }     } catch (filenotfoundexception e) {         e.printstacktrace();     } {         if (scanner != null) {             scanner.close();         }         if (pw != null) {             pw.close();         }     } } 

after running above, generated output.csv (based on input.csv) -

row_no, user, actions 1, john, sql transaction 2, suman, transaction failed 3, ram, button pressed retrieve details