重新提示用户在Java中输入有效输入

问题描述：

我有一个请求用户输入的代码，它运行得很好，但是我想再次提示用户输入有效的响应，而不是继续运行.

I have a code that requests input from the user, it runs just fine however I want to re-prompt the user to input a valid response instead of continuing to run.

代码如下:

import java.io.*;
public class SkiLodge {

    public static void main(String[] args) throws Exception
    {

        InputStreamReader ui = new InputStreamReader (System.in);
        BufferedReader inputReader = new BufferedReader(ui);

        System.out.println("Select Membership Type: (Gold/Silver/Bronze)");
        String membership = inputReader.readLine();

        double x = 0d;

        if (membership.equals("Gold"))
            System.out.println("Gold Membership Selected: £" + (x = 750));
        else if (membership.equals("Silver"))
            System.out.println("Silver Membership Selected: £" + (x = 450));
        else if (membership.equals("Bronze"))
            System.out.println("Bronze Membership Selected: £" + (x = 250));
        else System.out.println("Invalid Membership");



        System.out.println("Do you require snow tyre rental? (yes/no)");
        String tyreRental = inputReader.readLine();


        if (tyreRental.equals("yes"))
            System.out.println("The total so far with tyre rental: £" + (x = x * 1.1));
        else if (tyreRental.equals("no"))
            System.out.println("The total so far without tyre rental: £" + x);
        else System.out.println("Invalid response");

        System.out.println("Would you like to reserve parking? (yes/no)");
        String parking = inputReader.readLine();

        if (parking.equals("yes"))
        System.out.println("Membership total: £" + (x = x * 1.08));
        else if (parking.equals("no"))
        System.out.println("Membership total: £" + x);
        else System.out.println("Invalid response");
    }

}

例如，如果用户输入Gold，程序将打印出750，否则输入无效的会员资格，并要求提供有效的会员资格.

So for example if the user inputs Gold, the program prints out 750, if not then it prints out invalid membership and asks for a valid one.

以下问题相同，因此该程序仅接受是和否作为有效响应.

Same goes for the following questions, so the program only accepts yes and no as valid responses.

预先感谢

答

您可以使用do-while循环.

You can use a do-while loop.

do{
    //Some code here

    //if block
    else { // last else block.
         System.out.println("Invalid Membership");
         continue;  // This will skip the rest of the code and move again to the beginning of the while loop.
    }

    //More code

    break; // If the condition was correct, then you need not worry. This statement will pull out of the loop.
}while(true);

您可以对其进行修改，以在需要的任何地方放置一个do-while循环.

You can modify this to put a do-while loop any where you have such requirement.

这将使您的整个代码成为:

This would make your whole code to:

public static void main(String[] args) throws Exception
{

    InputStreamReader ui = new InputStreamReader (System.in);
    BufferedReader inputReader = new BufferedReader(ui);
    String membership, tyreRental,parking;
    double x = 0d;
    do
    {
        System.out.println("Select Membership Type: (Gold/Silver/Bronze)");
        membership = inputReader.readLine();

        if (membership.equals("Gold"))
            System.out.println("Gold Membership Selected: £" + (x = 750));
        else if (membership.equals("Silver"))
            System.out.println("Silver Membership Selected: £" + (x = 450));
        else if (membership.equals("Bronze"))
            System.out.println("Bronze Membership Selected: £" + (x = 250));
        else{
            System.out.println("Invalid Membership");
            continue;
        }
        break;
    }while(true);

    do{
        System.out.println("Do you require snow tyre rental? (yes/no)");
        tyreRental = inputReader.readLine();

        if (tyreRental.equals("yes"))
            System.out.println("The total so far with tyre rental: £" + (x = x * 1.1));
        else if (tyreRental.equals("no"))
            System.out.println("The total so far without tyre rental: £" + x);
        else{ System.out.println("Invalid response"); continue;}
        break;
    }while(true);

    do{
        System.out.println("Would you like to reserve parking? (yes/no)");
        parking = inputReader.readLine();

        if (parking.equals("yes"))
            System.out.println("Membership total: £" + (x = x * 1.08));
        else if (parking.equals("no"))
            System.out.println("Membership total: £" + x);
        else {System.out.println("Invalid response"); continue;}
        break;
    }while(true);
}

重新提示用户在Java中输入有效输入

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