code: private int defaultSentenceBreak(String s) {
          // scan for period followed by whitespace
          int period = -1;
          for (int i = 0; i < s.length(); i++) {
              switch (s.charAt(i)) {
                  case '.':
                      period = i;
                      break;
  
                  case ' ':
                  case '\f':
                  case '\n':
                  case '\r':
                  case '\t':
                      if (period >= 0) {
                          return i;
                      }
                      break;
  
                  default:
                      period = -1;
                      break;
              }
          }
          return -1;
      }
docs: /*
  Computes the first sentence break, a simple dot-space algorithm.