java - Declaring scanner to read system.in -

java - Declaring scanner to read system.in -

looking @ java tutorials, seems have wrap multiple layers of objects when declaring scanner e.g. http://docs.oracle.com/javase/tutorial/essential/io/scanning.html

s = new scanner(new bufferedreader(new filereader("xanadu.txt")));

has both bufferedreader , filereader. however, if i'm reading system.in need / there benefit doing this? 2 options behave differently?

scanner s = new scanner(new bufferedreader(new inputstreamreader( system.in)));

vs

scanner s = new scanner(system.in);

difference in efficiency. if used bufferedreader prevents bytes read file converted characters , returned back. using bufferedreader recommended.

additionally, can specify buffer size, handy.

java java.util.scanner system.in