java.util.NoSuchElementException:未找到行，是否需要处理此异常？

我的程序可以编译，但我遇到运行时异常，不确定是否需要处理它们？方法被注释掉，对于扩展类，它们只显示文本。我也不知道我是否正确使用了标签？我希望我的程序能够循环并处理错误字符的异常，但只有在用户输入“5”时才会终止

---

您的程序存在多个问题：

您定义了shouldExit，但没有根据用户输入更新它

可以在main（）和menu（）中扫描和处理用户输入。通常，您的代码不是以连贯可读的方式构造的，并且很少重用

println（）

已打印新行（与

print（）

相反）

出于对编程女神的热爱-不要使用System.exit（）终止Java程序

以下是一个工人阶级的例子，他们将上述指导方针实施到了可接受的程度：

import java.util.*;

public class Mainmenu3
{
    static Scanner in;

    public static void main(String args[])
    {
        in = new Scanner(System.in);
        boolean shouldExit = false;
        while (!shouldExit) {
            displayMenu();
            shouldExit = processUserInput();
        }
    }

    public static void displayMenu()
    {
        System.out.println();
        System.out.println("Created by Darren Estcourt");
        System.out.println("Please choose an option : ");
        System.out.println("1. Choose team");
        System.out.println("2. Create profile");
        System.out.println("3. Load/Save game");
        System.out.println("4. Credits");
        System.out.println("5. Quit");
    }

    public static int getUserInput()
    {
        int option = -1;
        try {
            option = in.nextInt();
        } catch (InputMismatchException e) {
            // When a scanner throws an InputMismatchException, 
            // the scanner will not pass the token that caused the exception,
            // so that it may be retrieved or skipped via some other method.
            in.next();
        } catch (NoSuchElementException e) {
            // input is exhausted
            option = 5;
        } catch (IllegalStateException e) {}
            // scanner is closed
            option = 5;
        }
        return option;
    }

    public static boolean processUserInput()
    {
        int option = getUserInput();
        switch (option) {
        case 1:
            chooseTeam();
            break;
        case 2:
            createProfile();
            break;
        case 3:
            loadSave();
            break;
        case 4:
            credits();
            break;
        case 5:
            System.out.println("Goodbye!");
            return true;
        default:
            System.out.println("Invalid choice");
        }
        return false;
    }

    public static void chooseTeam()
    {
        System.out.println();
        System.out.println("Select Team : ");
        System.out.println("1. Arsenal");
        System.out.println("2. Aston Villa");
        System.out.println("3. Bournemouth");
        System.out.println("4. Chelsea");
        System.out.println("5. Crystal Palace");
        System.out.println("6. Everton");
        System.out.println("7. Leicester City");
        System.out.println("8. Liverpool");
        System.out.println("9. Manchester United");
        System.out.println("10. Manchester City");
        System.out.println("11. Newcastle United");
        System.out.println("12. Norwich City");
        System.out.println("13. Southampton");
        System.out.println("14. Stoke City");
        System.out.println("15. Sunderland");
        System.out.println("16. Swansea City");
        System.out.println("17. Tottenham Hotspur");
        System.out.println("18. Watford");
        System.out.println("19. West Brom");
        System.out.println("20. West Ham United");

        int option = getUserInput();

        System.out.println("You entered : " + option);
    } // end chooseTeam

    public static void createProfile()
    {
        System.out.println("createProfile");
    }

    public static void loadSave()
    {
        System.out.println("loadSave");
    }

    public static void credits()
    {
        System.out.println("credits");
    }
}

---

请提供一个stacktrace，如果它们不相关，请删除注释代码。我想处理InputMismatchException。如果用户输入一个字符，这个程序（sharonbn解决方案）将进入一个永久循环！还有其他人有解决办法吗？所需要的只是再多做一点研究，以找出原因。我修复了答案中的

getUserInput（）

方法（现在您可以看到重用代码有什么好处：）

import java.util.*;

public class Mainmenu3
{
    static Scanner in;

    public static void main(String args[])
    {
        in = new Scanner(System.in);
        boolean shouldExit = false;
        while (!shouldExit) {
            displayMenu();
            shouldExit = processUserInput();
        }
    }

    public static void displayMenu()
    {
        System.out.println();
        System.out.println("Created by Darren Estcourt");
        System.out.println("Please choose an option : ");
        System.out.println("1. Choose team");
        System.out.println("2. Create profile");
        System.out.println("3. Load/Save game");
        System.out.println("4. Credits");
        System.out.println("5. Quit");
    }

    public static int getUserInput()
    {
        int option = -1;
        try {
            option = in.nextInt();
        } catch (InputMismatchException e) {
            // When a scanner throws an InputMismatchException, 
            // the scanner will not pass the token that caused the exception,
            // so that it may be retrieved or skipped via some other method.
            in.next();
        } catch (NoSuchElementException e) {
            // input is exhausted
            option = 5;
        } catch (IllegalStateException e) {}
            // scanner is closed
            option = 5;
        }
        return option;
    }

    public static boolean processUserInput()
    {
        int option = getUserInput();
        switch (option) {
        case 1:
            chooseTeam();
            break;
        case 2:
            createProfile();
            break;
        case 3:
            loadSave();
            break;
        case 4:
            credits();
            break;
        case 5:
            System.out.println("Goodbye!");
            return true;
        default:
            System.out.println("Invalid choice");
        }
        return false;
    }

    public static void chooseTeam()
    {
        System.out.println();
        System.out.println("Select Team : ");
        System.out.println("1. Arsenal");
        System.out.println("2. Aston Villa");
        System.out.println("3. Bournemouth");
        System.out.println("4. Chelsea");
        System.out.println("5. Crystal Palace");
        System.out.println("6. Everton");
        System.out.println("7. Leicester City");
        System.out.println("8. Liverpool");
        System.out.println("9. Manchester United");
        System.out.println("10. Manchester City");
        System.out.println("11. Newcastle United");
        System.out.println("12. Norwich City");
        System.out.println("13. Southampton");
        System.out.println("14. Stoke City");
        System.out.println("15. Sunderland");
        System.out.println("16. Swansea City");
        System.out.println("17. Tottenham Hotspur");
        System.out.println("18. Watford");
        System.out.println("19. West Brom");
        System.out.println("20. West Ham United");

        int option = getUserInput();

        System.out.println("You entered : " + option);
    } // end chooseTeam

    public static void createProfile()
    {
        System.out.println("createProfile");
    }

    public static void loadSave()
    {
        System.out.println("loadSave");
    }

    public static void credits()
    {
        System.out.println("credits");
    }
}