java: An algorithm for converting an array to comma delimited/separated string/value (e.g. csv)

StringBuilder sb = new StringBuilder();

Long[] array = {new Long("1"), new Long("2"), new Long("3")};

for (int i = 0; i < array.length(); i++)
{
   if (i > 0) 
   {
       sb.append(", ");
   }

   sb.append(array[i]);
}

System.out.println(sb.toString());

//output: 1, 2, 3