Feed a Scanner via String

Question

Heres my basic goal: Convert a program that uses a Scanner and the keyboard as input into a program that uses the Scanner and java args as input. This will be done programatically for a variety of programs, so I'd like to make as few and as small changes to the actual program itself. I'm able to do this by changing Scanner scanner = new Scanner(System.in); into Scanner scanner = new Scanner(args[0]);.

Now I can seperate each argument with a space in args[0] and the program runs fine, but ONLY if it doesn't use scanner.nextLine(). As soon as scanner.nextLine() is used, the scanner munches up the entire String and breaks the program.

I can't figure out a workaround without changing the program structure all together (Removing all the scanner.nextLine()s. Is there maybe some sort of character/sequence that will stop scanner.nextLine(), or will it always process the entire String?

Thanks

Edit: My initial idea was to give the scanner a String array and have it go through that, index by index, regardless of which method was used (next, nextInt, nextLine). Is that perhaps possible?

markspace · Accepted Answer · 2014-11-12 02:21:34Z

Look at Apache Commons CLI, it would almost certainly be better than trying to "convert" (kludge) a program that is currently using Scanner.

You can just insert newlines in the command line arguments if you really need to.

public static void main( String[] args ) { StringBuilder cla = new StringBuilder(); for( String command : args ) { cla.append( command ); cla.append( '\n' ); // newline } String finalCommand = cla.toString(); }

I'm actually basically finished the project, I just have this bug and then some GUI and finalizing stuff. If #2 works, I'll use that. Otherwise I'll redesign and attempt #1. The \n idea should work well, thanks!

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