Question

我想在输入字符或错误字符时不断抛出错误消息，我的循环适用于1-5以外的数字。
我的班级premierLeagueClubs只显示文字。我猜我需要try catch块，可能是InputMismatchException，但我不确定代码中的哪个地方可以放这个？

    import java.util.*;
    import java.util.InputMismatchException;
    import java.util.Scanner;

    public class Mainmenu3 extends premierLeagueClubs{

    public static void main(String args[]){
            boolean valid = false;
            int option = 0;

 while (!valid) {
        Scanner in = new Scanner(System.in);     
        menu();
        System.out.println("\n");
        option = in.nextInt();
        valid = option > 0 && option < 6;
        switch (option) {
            case 1:
        chooseTeam();

        case 2: 
        createProfile();
        //break;

        case 3:
        loadSave();
    //  break;

        case 4:
        credits();  
    //  break;

        case 5:
        System.out.println("Goodbye!"); 
    }
        } // end switch

       } // end main method

    public static void chooseTeam(){
    System.out.println("\n\n\n\n\n\n\n\n\n\n\n\n\n\n");
    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 = 0;

        Scanner in = new Scanner(System.in);
        //menu();

        System.out.println("\n");
        option = in.nextInt();
        System.out.println("You entered : " + option);

        if (option == 1)    
        arsenal();
        else 

            if (option == 2)
        astonVilla();
        else

        if (option == 3)
        bournemouth();
        else

        if (option == 4)
        chelsea();

        else 
        if (option == 5)
        crystalPalace();    

        else
        if (option == 6)
        everton();

        else
        if (option == 7)
        leicester();

        else
        if (option == 8)
        liverpool();

        else
        if (option == 9)
        manchesterUnited();

        else
        if (option == 10)
        manchesterCity();

        else
        if (option == 11)
        newcastleUnited();

        else
        if (option == 12)
        norwichCity();

        else
        if (option == 13)
        southampton();

        else
        if (option == 14)
        stokeCity();

        else
        if (option == 15)
        sunderland();

        else
        if (option == 16)
        swanseaCity();

        else
        if (option == 17)
        tottenhamHotspur();

        else
        if (option == 18)
        watford();

        else
        if (option == 19)
        westBrom();

        else
        if (option == 20)
        westHamUnited();    


    } // end chooseTeam



    public static void createProfile(){
    } // end createProfile
    public static void loadSave(){
    } // end loadSave
    public static void credits(){
    } // end credits


    public static void menu(){



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

        System.out.println("\n");

        String option="0";



        Scanner in = new Scanner(System.in);

        System.out.println("\n");
        option = in.nextLine();

        switch (option) {

        case "1":
        chooseTeam();
        break;

        case "2":   
        createProfile();
        break;

        case "3":
        loadSave();
        break;

        case "4":
        credits();  
        break;

        case "5":
        System.out.println("Goodbye!"); 

        default:
        System.out.println("Please select an option between 1 and 4");
    //menu();
        } // end switch



    } // end menu




    } // end class

Answer 1

抛出异常可能不是最好的主意，因为如果处理不当会阻止你的程序。正如Sernd建议的那样，添加默认案例似乎就像这里的简单解决方案

boolean shouldExit = false;
while (!shouldExit) {
    Scanner in = new Scanner(System.in);     
    menu();
    System.out.println("\n");
    option = in.nextInt();
    switch (option) {
        case 1:
          chooseTeam();
          break;
        case 2: 
          createProfile();
          break;
        case 3:
          loadSave();
          break;
        case 4:
          credits();  
          break;
        case 5:
          System.out.println("Goodbye!");
          shouldExit=true; 
          break;
        default:
         System.out.println("invalid selection");
    }
}

如何将字母和错误字符作为输入停止

1 个答案: