From a quick google:
There is also one specifier that doesn’t correspond to an argument. It is “%n” which outputs a line break. A “n” can also be used in some cases, but since “%n” always outputs the correct platform-specific line separator, it is portable across platforms whereas”n” is not.
Please refer
https://docs.oracle.com/javase/tutorial/java/data/numberformat.html
Original source
%n is portable across platforms
n is not.
See the formatting string syntax in the reference documentation:
‘n’ line separator The result is the
platform-specific line separator