How to re-prompt a user for input if they enter a string with multiple whitespaces

Question

So i am wondering how I can check a string that has been inputed by the user for multiple spaces, and if it does have multiple spaces between words, i want the user to be re-prompted for input. I am using a do- while loop. here is the format:

Scanner scanner01 = new Scanner(System.in);
String inputLast;
do {
    System.out.println("Enter a valid LAST name: ");
    inputLast = scanner01.nextLine();
} while()

Why don't you just remove additional spaces instead of annoying the user with it? — mhafellner, Jul 22 '13 at 15:08
because the input can have at least 1 consecutive whitespace between words. its when the user enters 2 consecutive whitespaces is when there should be an error. — madman75, Jul 22 '13 at 15:11

score 0 · Answer 1 · edited May 23 '17 at 11:57

0

For explanation how to replace multiple spaces with single space read how-to-replace-2-or-more-spaces-with-single-space-in-string.

edited May 23 '17 at 11:57

Community

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answered Jul 22 '13 at 15:11

mhafellner

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score 0 · Answer 2 · edited May 23 '17 at 12:29

0

One solution would be this (based on this answer):

   Scanner scanner01 = new Scanner(System.in);
   String inputLast;
   do {
       System.out.println("Enter a valid LAST name: ");
       inputLast = scanner01.nextLine();
       if(inputLast.length() - inputLast.replaceAll(" ", "").length() <= 1){
           break;
       }
   } while(true);

edited May 23 '17 at 12:29

Community

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answered Jul 22 '13 at 15:27

htulipe

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score 0 · Answer 3 · edited Jul 22 '13 at 15:44

0

String str = "Sam  ple";
Pattern pattern = Pattern.compile("\\s{2,}");
Matcher matcher = pattern.matcher(str);
boolean check = matcher.find();

edited Jul 22 '13 at 15:44

bensiu

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answered Jul 22 '13 at 15:27

Prabhakaran Ramaswamy

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How to re-prompt a user for input if they enter a string with multiple whitespaces

3 Answers3