Question

I am validating a particular column in a CSV file , I have basically two approaches i.e

• Approach 1
  I can Read the CSV file line by line with a BufferedReader and Stop when
  I hit a line that startsWith the thing I’m looking for

  try {   
       BufferedReader br = new BufferedReader(
           new InputStreamReader(item.getInputStream()));
  String strLine = "";
  StringTokenizer st = null;
  String value = "";
  while ((strLine = br.readLine()) != null) {
      st = new StringTokenizer(strLine, ",");
      while (st.hasMoreTokens()) {
          value = st.nextToken();
          if ((value != null) && (("MyString1".equals(value)
              || ("MyString2".equals(value)
              || ("MyString3".equals(value)))  {
              // Send error Message   
          }
      }
  }
  

• Second Approach is use a String.split as below

  Scanner s = new Scanner(item.getInputStream());  
  while(s.hasNextLine()) {  
      String[] fields = s.nextLine().split("\\s*,\\s*", -1);  
      for(int i = 0;i < fields.length;i++) {  
          if(!"".equals(fields[i]) && ...  
      }  
  }  
  s.close();
  

Please suggest a better approach

Answer 1

Don’t write your own CSV parser. CSV is actually more complicated than you might at first guess. (Examples: multi-line values, encapsulated fields, escaped characters, and more. Commas don’t always separate fields!)

Use opencsv, which is a full-featured pure-Java CSV parser.

This parser will easily let you loop over a CSV file, and process individual columns and rows. Examples are given in the link above.

Edit: Also, I forgot to mention, it is Apache2 licensed, so it can safely be embedded in commercial projects!