使用多个扫描仪有什么好处？

Question

What is the advantage or use of using multiple scanner objects in a program?

Scanner sc = new Scanner(System.in); 

as opposed to something like

Scanner sc1 = new Scanner(System.in);
Scanner sc2 = new Scanner(System.in);

in the same program.

Answer 1

I can see no advantage to the second bit of code:

Scanner sc1 = new Scanner(System.in);
Scanner sc2 = new Scanner(System.in);

and in fact there is some risk, risk if you close one Scanner (and thus the System.in ) before the other Scanner is done using it.

Instead, I can definitely see using more than one Scanner at times, but only one primary Scanner linking to System.in . Other Scanners can parse a line obtained. For example, use the main Scanner to get each line of text, and then use a second Scanner that has been fed the individual lines to parse the information held in the lines.

eg,

Scanner sc = new Scanner(System.in); 
while (sc.hasNextLine()) {
    String line = sc.nextLine();
    Scanner lineScanner = new Scanner(line);
    //.... parse line...
    lineScanner.close();
}
sc.close();