mark
Marks the present position in the stream. Subsequent calls to reset() will reposition the stream to this point.
Parameters
readAheadLimit
Limit on the number of characters that may be read while still preserving the mark. Because the stream's input comes from a string, there is no actual limit, so this argument must not be negative, but is otherwise ignored.
Throws
If readAheadLimit < 0
IOException
If an I/O error occurs