if (readerClosed) throw new IOException("Reader has been closed; cannot mark a closed reader.");
if (readerClosed) throw new IOException("Reader has been closed; cannot mark a closed Reader.");
        public void mark(int readAheadLimit) throws IOException {            synchronized (CircularCharBuffer.this){                if (readerClosed) throw new IOException("Reader has been closed; cannot mark a closed reader.");                if (buffer.length - 1 <= readAheadLimit) throw new IOException("Cannot mark stream, readAheadLimit bigger than buffer size.");                markSize = readAheadLimit;                markPosition = readPosition;            }        }