Is System.out buffered or unbuffered?

Question

Is System.out buffered or unbuffered?

I read this is an object of InputStream and PrinterStream is the type of object referenced by System.out.

And they Both are Unbuffered so Why println() flushes the unbuffered...is it possible to flush unbuffered and I have read they are written immediately.

Answer 1

System.out is the "standard" output. On most operating systems that terminal io is buffered, and paging is supported.

From the Javadoc,

The "standard" output stream. This stream is already open and ready to accept output data. Typically this stream corresponds to display output or another output destination specified by the host environment or user.

Answer 2

From http://docs.oracle.com/javase/8/docs/api/java/io/PrintStream.html :

Optionally, a PrintStream can be created so as to flush automatically; this means that the flush method is automatically invoked after a byte array is written, one of the println methods is invoked, or a newline character or byte ('\n') is written.