司机考试多选题数组同时循环提示学生答题方法

Question

在这里寻找一些帮助。我正在尝试让这个方法起作用。每当我运行该方法时，即使我键入A、B、C或D，它也会抛出IllegalArgumentException。我使用的是inputReader类。下面是我的DriverExam类的代码。请告诉我哪里出错了。我喜欢它，这样唯一有效的答案是a，b，c或d。我必须使用while循环，但我尝试的所有东西都不能帮助我匹配driverAnswers。

public class DriverExam
{
    // instance variables
    public static final String[] ANSWERS = {"B","D","A","A","C","A","B","A","C","D","B","C","D","A","D","C","C","B","D","A"};

    private String [] driverAnswers;
    private InputReader inputReader;

    public DriverExam(){
        driverAnswers = new String[20];
        inputReader = new InputReader();
    }

    public void promptStudentAnswers(){
        int index = 0;

        while(index < driverAnswers.length){
            System.out.println("enter answer");
            String driverAnswers = inputReader.readString();
            if(driverAnswers != ANSWERS[index]){
                throw new IllegalArgumentException(" answers can only be A,B,C or D");
            } else{ 
                index++;
            }
        }
    }
}

Answer 1

首先，您希望测试答案是A、B、C或D中的一个(不是该答案与正确答案数组中的某项匹配)。此外，您的driverAnswers会被屏蔽，因为您创建了另一个同名的局部变量。基本上，我认为你想要的东西

public void promptStudentAnswers() {
    int index = 0;

    while (index < driverAnswers.length) {
        System.out.println("enter answer");
        String answer = inputReader.readString().trim().toUpperCase();
        if (answer.length() == 1 && "ABCD".indexOf(answer) != -1) {
            driverAnswers[index] = answer;
            index++;
        } else {
            System.out.println("Answers can only be A,B,C or D");
        }
    }
}