How to declare "Scanner"

[Jens Jensen]

Hi developers,

is it okay to declare the "Scanner" before the main method?

public class Main {
	public static Scanner scan = new Scanner(System.in);
	
	public static void main(String[] args) {
}

I want it to be useable in every method in my program without the need of having to create it in every method again.
Is this the way to go or is there a better solution?

Thanks in advance and best regards,
Jens

[Campbell Ritchie]

Yes, that will work. Much better than re‑declaring it. I would declare it in a different class and make it final, because, as you correctly said, you only need one Scanner per (single‑threaded) application. Once initialised, it never needs to be re‑assigned.

public class Resources
{
   // ...
   public static final Scanner input = new Scanner(System.in);
   // ...
}
// ...
XYZ xyz = input.nextXyz();

I think there is a better way to get keyboard input, but you will have to devote a few hours' work to it. I have written myself a utility class. Search my posts for “utility class Scanner” and you will find it, but only in pieces which you will have to assemble. I can write

int dogCount = KeyboardInputs.nextInt( "Please enter number of dogs: ");
String name  = KeyboardInputs.nextLine("Please enter name of kennel: ");

...and it is so written that the problem about getting an empty line from nextLine() doesn't occur. If you use that class in any code you are giving to anybody else, please acknowledge its course in its first comment.

[Stephan van Hulst]

Jens Jensen wrote:Is this the way to go or is there a better solution?

Inject the Scanner into the constructors of the classes that need it.

I can't imagine there are many classes that need user input. If there are, you probably need to redesign your application.

[Jens Jensen]

Thanks all for your input!
Appreciate it.

Best regards,
Jens