code: public String join(int[] array, String separator) {
          int size = array.length;
          StringBuilder buffer = new StringBuilder(512);
          for (int i = 0; i < size; i++) {
              int item = array[i];
              if (i > 0) { buffer.append(separator); }
              buffer.append(item);
          }
          
          return buffer.toString();
      }
docs: Join the contents of the given array separated by the given separator.
  For example, the array [a, b, c] with separator ' ' would result in:
  <code>a b c</code>.
  
  @param array  The array to join
  @param separator The separator between values
  
  @return The resulting string