What is system.in

Question

Consider this Scanner input example.

Scanner user_input = new Scanner( System.in );

Here Scanner is the CLASS.

Answer 1

From the source:

System.in is an InputStream which is typically connected to keyboard input of console programs. System.in is not used as often since data is commonly passed to a command line Java application via command line arguments, or configuration files. In applications with GUI the input to the application is given via the GUI. This is a separate input mechanism from Java IO.