java - 循环回到代码开头

Question

我见过一些这样的线程，但我不完全理解如何将它实现到我的代码中。

import java.util.Scanner;

public class Test {



    public static void main(String[] args)throws java.io.IOException {



        Scanner reader = new Scanner(System.in);

        System.out.println("Enter a number between 1-1000: ");

        int n = reader.nextInt();

        if(90<=n && n<=110) System.out.println(n + " is close to 100");
        if(190<=n && n<=210) System.out.println(n + " is close to 200");
        if(290<=n && n<=310) System.out.println(n + " is close to 300");
        if(390<=n && n<=410) System.out.println(n + " is close to 400");
        if(490<=n && n<=510) System.out.println(n + " is close to 500");
        if(590<=n && n<=610) System.out.println(n + " is close to 600");
        if(690<=n && n<=710) System.out.println(n + " is close to 700");
        if(790<=n && n<=810) System.out.println(n + " is close to 800");
        if(890<=n && n<=910) System.out.println(n + " is close to 900");
        if(n>1000)System.out.println("Your number is too high");
        else System.out.println("Your number is not close to any 100s");


    }

}       

如果整数超过 1000，我希望它能以某种方式循环回到用户输入部分。

Answer 1

您可以使用 while 循环，并且仅当输入的数字低于 1 或高于 1000 时才跳出循环

import java.util.Scanner;

public class Test {



public static void main(String[] args) throws java.io.IOException {


    Scanner reader = new Scanner(System. in );
    Boolean exit = false;

    while (!exit) {
        System.out.println("Enter a number between 1-1000: ");
        int n = reader.nextInt();
        if (n < 0 || n > 1000) {

            System.out.println("That number was invalid");
        } else {
            exit = true;
            if (90 <= n && n <= 110) System.out.println(n + " is close to 100");
            if (190 <= n && n <= 210) System.out.println(n + " is close to 200");
            if (290 <= n && n <= 310) System.out.println(n + " is close to 300");
            if (390 <= n && n <= 410) System.out.println(n + " is close to 400");
            if (490 <= n && n <= 510) System.out.println(n + " is close to 500");
            if (590 <= n && n <= 610) System.out.println(n + " is close to 600");
            if (690 <= n && n <= 710) System.out.println(n + " is close to 700");
            if (790 <= n && n <= 810) System.out.println(n + " is close to 800");
            if (890 <= n && n <= 910) System.out.println(n + " is close to 900");
        }
    }
}

}