在Java中使用扫描仪时出错

Question

What's the problem with the object scanner in this code ?

void exp03(){
    System.out.println("---CREATION DES POINTS---");
    char res = 'O';
    Scanner sc = new Scanner(System.in);
       do{
        Point a = new Point();
        try{
        System.out.println("Entrez la valeur du coordonnée du point suivant X");
        double resx = sc.nextDouble();
        a.setX(resx);
        System.out.println("Entrez la valeur du coordonnée du point suivant Y");
        double resy = sc.nextDouble();
        a.setY(resy);
        }
        catch(CoorExp e){
        System.out.println("ERREUR:coordonnée négative!");  //exit  
        }
        System.out.println("1- Afficher le point creer");
        System.out.println("2- Deplacer le point creer");
        int i = sc.nextInt();
        switch (i){

        case 1 : 
            break;

        case 2 :
            System.out.println("entrer la valeur de deplacement suivant X");
            double depx =sc.nextDouble();
            a.setDx(depx);
            System.out.println("entrer la valeur de deplacement suivant Y");
            double depy =sc.nextDouble();
            a.setDy(depy);
            a.deplace(depx, depy);
            System.out.println("Nouvelles coordonnées du point");
            a.affiche();
            break;
        default:
            System.out.println("Choix Incorrect ! ");


        }
        System.out.println("Voulez vous creez un autre point ? O/N");//exception
        res = sc.next().charAt(0);
        }
        while(res == 'O');  

}

When I chose case 2 , I get this error:

 > Exception in thread "main" java.util.InputMismatchException 
 > java.util.Scanner.throwFor(Scanner.java:864) 
 > java.util.Scanner.next(Scanner.java:1485) 
 > java.util.Scanner.nextDouble(Scanner.java:2413) 
 > com.mbisc.java.Test.exp03(Test.java:115) 
 > com.mbisc.java.Test.<init>(Test.java:9) 
 > com.mbisc.java.Test.main(Test.java:137)

i thing it that scanner is first declare as an int and now after the switch i collect answer with a type double. I'm not pretty sure and i need to understand more how the scanner class works.

Answer 1

Firstly you have to check whether a double had been read:

if (sc.hasNextDouble())
     double depx = sc.nextDouble();

It may be that a double is not there.

---

Or you should state a Locale for your Scanner .

Scanner sc = new Scanner(System.in).useLocale(Locale.US);