驾驶员考试多选数组同时循环提示学生答案方法

Question

在此处寻求帮助。我正在努力使这种方法奏效。每当我运行该方法时，即使我键入了A、B、C或D，它也会抛出IllegalArgumentException。我使用的是inputReader类。这是我的DriverExam类的代码。请告诉我哪里出了问题。我想要它，所以唯一有效的答案是a、b、c或d。我必须使用while循环，我所尝试的一切都无法帮助我匹配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，您想测试答案是A、B、C还是D中的一个(而不是说答案与正确答案数组中的某个匹配(。此外，您的driverAnswers被屏蔽，因为您创建了另一个具有该名称的局部变量。基本上，我认为你想要类似的东西

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");
}
}
}