Java Read/Write CSV file sample

public static void TempPreProcessor_CSV(String input, String output){
 //IDataSharedCursor idc = pipeline.getSharedCursor();
 BufferedReader reader = null;
 BufferedWriter writer = null;
 try 
 {
  String inputfilename = input;
  String outputfilename = output;

  reader = new BufferedReader(
               new InputStreamReader(
                   new FileInputStream(inputfilename)));
  writer = new BufferedWriter(
               new OutputStreamWriter(
                   new FileOutputStream(outputfilename)));
  int lineNum = 1;
  String checkNum = "";
  
  String thisLine = "";

  // comma, which is not enclosed in quotes
  String delims = ",(?=([^\"]*\"[^\"]*\")*[^\"]*$)";

  while((thisLine=reader.readLine()) != null){// till end of file
     StringBuffer sb = new StringBuffer();
     if(thisLine.trim().equals("")) 
                           continue; // ignore blank lines
   
     if (lineNum++ == 1){
      sb.append(thisLine + "\n");
      writer.write(sb.toString());
      continue;  
     }

     String[] thisTokens = thisLine.split(delims);                           
     if (!checkNum.equalsIgnoreCase(thisTokens[0].toString())){
         checkNum = thisTokens[0].toString();
         sb.append("AA," + thisLine);
     }else{
         sb.append("AB," + thisLine);
     }
     sb.append("\n");
     writer.write(sb.toString());
  }
 }catch(Exception e){
  //throw new ServiceException(
  //  "TempPreProcessor: Unknown errors: " + e.toString());
 }finally{
  try {
   if(writer != null) writer.flush();
   if(reader != null) reader.close();
   if(writer != null) writer.close();
   reader=null;
   writer=null;
   //idc.destroy();
  }catch(Exception e){
   //throw new ServiceException(
   //  "TempPreProcessor: Unknown errors: " + e.toString());
  }
 }
}