code: public String getLine(int pos) {
          try {
              if (!findLine(pos))
                  return null;
  
              int lineEnd = lineStart;
              while (lineEnd < bufLen && buf[lineEnd] != CR && buf[lineEnd] != LF)
                  lineEnd++;
              if (lineEnd - lineStart == 0)
                  return null;
              return new String(buf, lineStart, lineEnd - lineStart);
          } finally {
              buf = null;
          }
      }
docs: Return the content of the line containing a given pos.