線程“main”中的異常 java.util.NoSuchElementException（如何修復錯誤）

Question

這個錯誤讓我很緊張。

Exception in thread "main" java.util.NoSuchElementException
    at java.util.Scanner.throwFor(Scanner.java:862)
    at java.util.Scanner.next(Scanner.java:1485)
    at java.util.Scanner.nextInt(Scanner.java:2117)
    at java.util.Scanner.nextInt(Scanner.java:2076)
    at Main.main(Main.java:266)
    at Ideone.test(Main.java:72)
    at Ideone.test(Main.java:32)
    at Ideone.main(Main.java:23)

我的代碼：

import java.util.Scanner;
import java.lang.Math;

class Main {
  public static void main(String[] args){


      Scanner scan = new Scanner(System.in);

      System.out.println("Welcome. What is your name?");
      String x;
      x = scan.nextLine();

      System.out.println("Hello " + x + ". Try your best to crack the code!");
      System.out.println(" ");

//Phase 1
      System.out.println("PHASE 1");

      System.out.println("Enter a number:");
      int y = scan.nextInt();
      if (y == 3){
        System.out.println("Correct!");
        System.out.println(" ");
//Phase 2
        System.out.println("PHASE 2");
        System.out.println("Enter a number:");
      }
      int z = scan.nextInt();
      if (z == 1 || (z >= 33 && z <= 100)){
        System.out.println("Correct!");
        System.out.println(" ");
//Phase 3
        System.out.println("PHASE 3");
        System.out.println("Enter a number:");}
      int c = scan.nextInt();
      if (c % 3 == 0 || c % 7 == 0){
        System.out.println("Correct!");
        System.out.println("You have cracked the code!");}
      else{
        System.out.println("Sorry, that was incorrect!");
        System.out.println("Better luck next time!");}


    }
}

如果輸入不正確，想結束整個程序。 不確定到底出了什么問題。 現在被困在這個問題上一段時間了。 您如何找出掃描儀和輸入的問題？

Answer 1

您的錯誤純粹是邏輯錯誤。 你在不應該出現的地方都有}。 您也沒有消耗按 Enter 鍵在 nextInt() 上生成的 /n“新行”。

為避免混淆您對嵌套 if 的自用開頭和結尾注釋 在創建 if 時創建框架工作並使用空格將所有內容隔開是一個很好的做法。

if( conditon) 
{
      if_statement(s);
}
else
{
      else_statement(s);
}

這是您更正的代碼

import java.util.Scanner;
import java.lang.Math;

class BrockTaylor
{
    public static void main(String[] args)
    {
        Scanner scan = new Scanner(System.in);
        System.out.println("Welcome. What is your name?");
        String x;
        x = scan.nextLine();
        System.out.println("Hello " + x + ". Try your best to crack the code!");
        System.out.println(" ");
        System.out.println("PHASE 1");
        System.out.println("Enter a number:");
        int y = scan.nextInt();
        // consume the /n
        scan.nextLine();
        //Phase 1
        if (y == 3)
        {
            System.out.println("Correct!");
            System.out.println(" ");
            System.out.println("PHASE 2");
            System.out.println("Enter a number:");
            int z = scan.nextInt();
            // consume the /n
            scan.nextLine();
            //Phase 2
            if (z == 1 || z >= 33 && z <= 100)
            {
                System.out.println("Correct!");
                System.out.println(" ");
                System.out.println("PHASE 3");
                System.out.println("Enter a number:");
                int c = scan.nextInt();
                // consume the /n
                scan.nextLine();
                //Phase 3
                if (c % 3 == 0 || c % 7 == 0)
                {
                    System.out.println("Correct!");
                    System.out.println("You have cracked the code!");
                }
                else // phase 3
                {
                    System.out.println("Sorry, that was incorrect!");
                    System.out.println("Better luck next time!");
                }
            }
            else // phase 2
            {
                System.out.println("Sorry, that was incorrect!");
                System.out.println("Better luck next time!");
            }
        }
        else// phase 1
        {
        System.out.println("Sorry, that was incorrect!");
        System.out.println("Better luck next time!");
        }
    }
}