java - 如果参数不满足则重新启动while循环

Question

所以，这个程序可以工作，可以运行，但我希望它是白痴证明!为此，我需要一些帮助.. 如果用户输入数字或什么都不输入，我不希望它转到下一行!

如果我按 Enter 键而不写任何内容，它仍然会转到下一行，并且变量 navn 最后完全为空。 如果我写一个数字，它也会做同样的事情。如果答案不满足提示，我该如何让它返回并再次尝试相同的 while 循环。 非常感谢:)

import java.util.Scanner;

class Metoder {

    public static void main(String[] args) {
        String bosted; //Variable
        String navn; //Variable

        Scanner in = new Scanner(System.in);

        System.out.println("Skriv inn navn: "); //What shows up when you first start the program

        while (!in.hasNext("[A-Za-z]+")) { //Only allow letters A-Z
            in.next();
            System.out.println("Tall horer ikke hjemme i navn, prøv igjen!"); //Prints, "numbers dont belong in names, try again" if what the user entered is a number

        }
        System.out.println("Takk!"); //Says thank you if the user has entered letters

        navn = in.nextLine(); //Proceeds to next line

        System.out.println("Skriv inn bosted: "); //Next line, where the user is supposed to enter where he/she lives
        while (!in.hasNext("[A-Za-z]+")) { //Excactly the same loop as above
            in.next();
            System.out.println("Tall hører ikke hjemme i stedsnavn, prøv igjen!");
        }
        System.out.println("Takk!");

        bosted = in.nextLine();

        System.out.println("Hei, " + navn + "! Du er fra " + bosted + "."); //Prints out what the user has entered previously in a full sentence.

    }
}

Answer 1

请使用此代码:

  public static void main(String[] args) {
    String bosted=""; //Variable
    String navn=""; //Variable

    Scanner in = new Scanner(System.in);

    System.out.println("Skriv inn navn: "); //What shows up when you first start the program

    while(in.hasNext()) { //Only allow letters A-Z
         navn = in.nextLine();
        if(!navn.isEmpty() && navn.matches("[A-Za-z]+")){
             System.out.println("Takk!"); //Says thank you if the user has entered letters
             in.next();
             break;
        }
        else{
            System.out.println("Tall horer ikke hjemme i navn, prøv igjen!"); //Prints, "numbers dont belong in names, try again" if what the user entered is a number
            in.next();
            System.out.println("Skriv inn navn: ");
            continue;
        }

  }

    System.out.println("Skriv inn bosted: ");
    while(in.hasNext()) { //Only allow letters A-Z
        bosted = in.nextLine();
       if(!bosted.isEmpty() && bosted.matches("[A-Za-z]+")){
         System.out.println("Takk!"); //Says thank you if the user has entered letters
         break;
       }
       else{
           System.out.println("Tall horer ikke hjemme i navn, prøv igjen!"); //Prints, "numbers dont belong in names, try again" if what the user entered is a number
           in.next();
           System.out.println("Skriv inn bosted: ");
           continue;
       }


 }
    System.out.println("Hei, " + navn + "! Du er fra " + bosted + "."); //Prints out what the user has entered previously in a full sentence.
}