如何使反应时间在我的 while 循环中工作

Question

我正在编写一个项目来计算用户写答案所需的时间。 所以我会显示一个问题，你会回答它。 之后，我将显示您解决它所需的时间。

但是当我将变量放在我的 while 循环中时，反应时间不起作用。

这是代码：

long startTime = System.currentTimeMillis();
long endTime = System.currentTimeMillis();
long reactionTime = endTime - startTime;
//Q1
System.out.println("Q1");
while (true) {
    System.out.println("What is 1+1: ");
    int ans = scanner.nextInt();
    if (ans == 2) {
        System.out.println("Correct");
        System.out.println(reactionTime + "ms");
        break;
    } else {
        System.out.println("incorrect please try again");

    }
}

Answer 1

问题是你的结束时间和开始时间基本上是相等的，因为你甚至在问题被问到之前就把它们都拿走了。

要解决它，只需在用户的答案正确时计算所花费的时间。

// take the start time once before the user gets to answer your question
long startTime = System.currentTimeMillis();

//Q1
System.out.println("Q1");
while (true) {
    System.out.println("What is 1+1: ");
    int ans = scanner.nextInt();
    if (ans == 2) {
        System.out.println("Correct");

        // take the end time here, only if the answer of the user is correct
        long endTime = System.currentTimeMillis();
        long reactionTime = endTime - startTime;

        System.out.println(reactionTime + "ms");
    } else {
        System.out.println("incorrect please try again");
    }
}

Answer 2

public class Questionnaire {
    
    public static void main(String... args) {
        int totalQuestions = 10;
        Scanner scan = new Scanner(System.in);
        
        for (int i = 0; i < totalQuestions; i++) {
            String title = "What is 1+1: ";
            String correctAnswer = "2";
            long reactionTime = askQuestionAndGetReactionTimeMs(scan, title, correctAnswer);
            System.out.format("Reaction time: %dms\n\n", reactionTime);
        }
    }
    
    private static long askQuestionAndGetReactionTimeMs(Scanner scan, String title, String correctAnswer) {
        long beginTime = System.currentTimeMillis();
        
        while (true) {
            System.out.print(title);
            String answer = scan.next();
            
            if(correctAnswer.equals(answer))
                return System.currentTimeMillis() - beginTime;
            
            System.out.println("incorrect please try again")
        }
    }
}