java - Parsing CSV file with BufferedReader vs Scanner -

team, have parse file line line , in single line have split ",". first string name , second count. finaly have display key , count example

peter,2  smith,3 peter,3 smith,5 

i should display peter 5 , smith 8.

so in confusion choose between bufferedreader vs scanner. went through link . came these 2 approach. concerns.

approach 1 : use buffered reader.

private hashmap<string, mutablelong> readfile(file file) throws ioexception {         final hashmap<string, mutablelong> keyholder = new hashmap<>();         try (bufferedreader br = new bufferedreader(new inputstreamreader(                 new fileinputstream(file), "utf-8"))) {             (string line; (line = br.readline()) != null;) {                 // processing line.                 final string[] keycontents = line                         .split(keycountexam.comma_delimeter);                 if (keycontents.length == 2) {                     final string keyname = keycontents[0];                     final long count = long.parselong(keycontents[1]);                     final mutablelong keycount = keyholder.get(keyname);                     if (keycount != null) {                         keycount.add(count);                         keyholder.put(keyname, keycount);                     } else {                         keyholder.put(keyname, new mutablelong(count));                     }                 }              }         }         return keyholder;     }  private static final string comma_delimeter = ",";     private static volatile pattern commapattern = pattern             .compile(comma_delimeter); 

i have used mutablelong ( , since dont want create biginteger each time . , again may big file , don't have control on how max key can occur

another approach :

use scanner , use 2 delimiter

private static final string line_separator_pattern = "\r\n|[\n\r\u2028\u2029\u0085]";     private static final string line_pattern = ".*(" + line_separator_pattern             + ")|.+$";     private static volatile pattern linepattern = pattern.compile(line_pattern); 

my question . have went through hasnext in scanner , me there no harm switch pattern . , belive java 7, scanner has limited buffer can enough kind of file.

do 1 perfer approach 2 on approach 1 or have other option other this. did sop testing purpose. same code in approach 1 replace here. using split in approach1 create multiple string instances. can avoided here ( right) , scanning char sequence.

private hashmap<string, biginteger> readfilescanner(file file)             throws ioexception {         final hashmap<string, biginteger> keyholder = new hashmap<>();         try (scanner br = new scanner(file, "utf-8")) {             while (br.hasnext()) {                 br.usedelimiter(commapattern);                 system.out.println(br.next());                 system.out.println(br.next());                 br.usedelimiter(linepattern);             }         }         return keyholder;     }