java - Is there an easy way to output a column-wise CSV? -

i'm trying output multiple lists of data, of varying length, csv file. each list should column in output csv file. there straight-forward way of doing thing? if outputting each list row, i'd loop on each list , output return when hit end, approach not work when working column-wise.

i thought of going on lists @ once, item item , incrementing counter, fail because lists longer others. remedy have check @ each iteration whether counter past end of each list, expensive in terms of computations.

thanks ideas!

i think pretty straight-forward:

public static void main(string... args) throws ioexception {      arraylist<arraylist<string>> rows = getrandomdata();      if (rows.size() == 0)         throw new runtimeexception("no rows");      // normalize data     int longest = 0;     (list<string> row : rows)         if (row.size() > longest)             longest = row.size();      (list<string> row : rows)         while (row.size() < longest)             row.add("");      if (longest == 0)         throw new runtimeexception("no colums");      // fix special characters     (int = 0; < rows.size(); i++)         (int j = 0; j < rows.get(i).size(); j++)             rows.get(i).set(j, fixspecial(rows.get(i).get(j)));      // maximum size of 1 column     int[] maxcolumn = new int[rows.get(0).size()];      (int = 0; < rows.size(); i++)         (int j = 0; j < rows.get(i).size(); j++)             if (maxcolumn[j] < rows.get(i).get(j).length())                 maxcolumn[j] = rows.get(i).get(j).length();      // create format string     string outformat = "";     (int max : maxcolumn)         outformat += "%-" + (max + 1) + "s, ";     outformat = outformat.substring(0, outformat.length() - 2) + "\n";      // print data     (list<string> row : rows)         system.out.printf(outformat, row.toarray());  }  private static string fixspecial(string s) {      s = s.replaceall("(\")", "$1$1");      if (s.contains("\n") || s.contains(",") || s.contains("\"") ||              s.trim().length() < s.length()) {         s = "\"" + s + "\"";     }      return s; }  private static arraylist<arraylist<string>> getrandomdata() {      arraylist<arraylist<string>> data = new arraylist<arraylist<string>>();      string[] rand = { "do", "re", "song", "david", "test", "4", "hohjoh", "a \"h\" o", "tjo,ad" };     random r = new random(5);      (int = 0; < 10; i++) {          arraylist<string> row = new arraylist<string>();          (int j = 0; j < r.nextint(10); j++)             row.add(rand[r.nextint(rand.length)]);          data.add(row);     }      return data; } 

output (pretty ugly since random) (escapes):

re       , 4           , "tjo,ad" , "tjo,ad" ,     "tjo,ad" , "a ""h"" o" ,          ,          ,     re       , "a ""h"" o" , hohjoh   , "tjo,ad" , 4   4        , david       ,          ,          ,     4        , test        , "tjo,ad" , hohjoh   , re        , hohjoh      , test     ,          ,     hohjoh   , song        ,          ,          ,     4        , song        ,          ,          ,     4        ,          , song     ,       ,     song     , test        , test     ,          ,