在int字段中输入String时如何重复菜单？

debugcn 发表于 Dev

艾伦·特兰

我在下面有一个菜单，我希望在输入字符串而不是整数时重复菜单。我知道何时在“ in / nextInt（）;”中输入字符串。它立即崩溃。我想知道如何才能阻止现在的情况。

    Scanner in = new Scanner(System.in);

    do{
        System.out.println("");
        System.out.println("Please choose from the following options. " );
        System.out.println("");
        System.out.println("1. Do you want to use the default rotor settings?  ");
        System.out.println("2. Do you want to use the custom rotor settings?  ");
        System.out.println("3. Start over. ");
        System.out.println("");


        menuOneAnwser = in.nextInt();

    }while(menuOneAnwser < 0 || menuOneAnwser > 3);


    try{

        switch(menuOneAnwser){
            case 1:

                Enigma.defaultSwitch = true;
                break;
            case 2:
                Enigma.defaultSwitch = false;
                g.customRotor();

                break;  
            case 3:
                introduction();
                break;
            default:
                break;
        }

    }catch(InputMismatchException e){
        System.out.println("That is not a  integer.... Please enter a interger between 1 and 2!" );
        System.out.println("Please try again.." );
        System.out.println("");

    }

ΦXocę웃Пepeúpatsu

而不是直接调用scan.nextInt，而是尝试将该字符串转换为一个捕获异常菜单的整数，因为输入无效，然后将menuOneAnwser设置为-1

do{
        System.out.println("");
        System.out.println("Please choose from the following options. " );
        System.out.println("");
        System.out.println("1. Do you want to use the default rotor settings?  ");
        System.out.println("2. Do you want to use the custom rotor settings?  ");
        System.out.println("3. Start over. ");
        System.out.println("");

         try {
           menuOneAnwser = Integer.parseInt(input);
        } catch (NumberFormatException e) {
        menuOneAnwser = -1;
        }


    }while(menuOneAnwser < 0 || menuOneAnwser > 3);

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