Java standard output stream, standard error output stream, standard input stream, and scanner

 PackageCom.mydemo.controller;ImportJava.util.Scanner; Public classHelloWorld { Public Static voidMain (string[] args) {System.err.println ("HelloWorld"); System.out.println ("HelloWorld");        System.out.println (system.in);        System.out.println (System.out);                System.out.println (System.err); Scanner Scanner=NewScanner (system.in); String nextline=Scanner.nextline (); }}

Operation Result:

HelloWorld Helloworld[email protected][email Protected][email protected]

How to block the scanner:

1  PackageCom.mydemo.controller;2 3 ImportJava.util.Scanner;4 5  Public classHelloWorld {6      Public Static voidMain (string[] args) {7@SuppressWarnings ("Resource")8Scanner Scanner =NewScanner (system.in);//This line breaks the point9String nextline =Scanner.nextline (); This line breaks.Ten System.out.println (nextline); This line breaks. One     } A}

Debug Run:

Until the 9th line, press F6 will not go down, the console input will go down.

So the nextline () of the scanner object is a blocking method.

Java standard output stream, standard error output stream, standard input stream, and scanner