java - 使用 if 语句的用户提示

Question

我正在尝试编写一个程序来询问用户是否怀孕。我遇到的问题是，如果该人输入“可能”或“是”或“否”以外的任何其他响应，我希望程序说“这是一个是或否的问题”，然后提示用户再次回答问题。相反，它会打印“这是一个是或否的问题”和“你怀孕了吗？”但它不能接受另一个回答。这是我想要做的正确格式吗？换句话说，我希望我的程序一直询问用户她是否怀孕，直到我得到是或否的答案。

import acm.program.*;

public class AskProgram extends ConsoleProgram{
    public void run(){

        String answer = readLine(" are you pregnant? ");

        if (answer.equals("yes")) {
            println("Great! Congratulations ");
        } else if (answer.equals("no")) {
            println("keep trying it will happen."); 
        } else {
            println("Its a yes or no question");
            readline("are you pregnant? ");
        }          
    }
}

Answer 1

这将重复该块，直到用户输入“是”或“否”：

String answer = "";
while (!answer.equalsIgnoreCase("yes") && !answer.equalsIgnoreCase("no")) {
    answer = readLine("Are you pregnant?");
    if (answer.equalsIgnoreCase("yes")) {
        println("Great! Congratulations ");
        break;
    } else if (answer.equalsIgnoreCase("no")) {
        println("keep trying it will happen."); 
        break;
    } else {
        println("Its a yes or no question");
        readline("are you pregnant? ");
    }    
}

Answer 2

这是一个使用递归（和返回值）的版本：

private static boolean isPregnant() {
    String answer = readLine("Are you pregnant?");
    if (answer.equalsIgnoreCase("yes")) {
        println("Great! Congratulations ");
        return true;
    } else if (answer.equalsIgnoreCase("no")) {
        println("keep trying it will happen.");
        return false;
    } else {
        println("It's a yes or no question");
        return isPregnant();
    }

}