code: public static String getStringFromTokens(final String[] tokens) {
      final StringBuilder sb = new StringBuilder();
      for (final String tok : tokens) {
        sb.append(tok).append(" ");
      }
      return sb.toString().trim();
    }
docs: Gets the String joined by a space of an array of tokens.
  
  @param tokens
  an array of tokens representing a tokenized sentence
  @return sentence the sentence corresponding to the tokens