code: private boolean isClosed() {
          if (!verifyReader) {
              return false;
          }
          try {
              br.mark(READ_AHEAD_LIMIT);
              int nextByte = br.read();
              br.reset(); // resets stream position, possible because its buffered
              return nextByte == -1; // read() returns -1 at end of stream
          } catch (IOException e) {
              return true;
          }
      }
docs: Checks to see if the file is closed.
  @return true if the reader can no longer be read from.