尝试使用方法创建驾驶执照考试程序

Question

我正在尝试创建一个 Java 程序，用于对驾驶执照考试的书面部分进行评分，用户需要正确回答 20 个问题中的 15 个才能通过。应该有一种方法可以让用户输入他们的选择。包括输入验证，并且只接受字母 A、B、C 或 D。

还应该有第二种方法来评估学生的答案，显示正确回答的问题数量，学生是否通过了考试，并填充另一个数组来保存错误回答的问题编号。

第三种方法将显示错过的问题编号。

到目前为止我所拥有的：

import java.util.Scanner;

public class DriverLicenseExam 
{
   public static void main(String[] args)
   {
   // Arrays
   String[] correctAnswers = {"B", "D", "A", "A", "C", 
                              "A", "B", "A", "C", "D", 
                              "B", "C", "D", "A", "D", 
                              "C", "C", "B", "D", "A"};
   String[] userAnswers; 
   int[] missed = new int[correctAnswers.length];
   String[] answers = new String[20]; 
   String answer; 

   // User's input
   System.out.println("Enter your answers for the exam here: "); 
   Scanner input = new Scanner(System.in);
      for (int x = 0; x < 20; x++)
      {
         do
         {
            System.out.print((x+1) + ": "); 
            answer = input.nextLine(); 
         } 
         while (!isValidAnswer(answer)); 

         answers[x] = answer; 
      }

      //Process the user's answers
          userAnswers = new String[answers.length]; 

          for (int x = 0; x < answers.length; x++)
          {
             userAnswers[x] = answers[x]; 
          }


      //Results 
      int correctCount = totalCorrect();
      int incorrectCount = totalIncorrect();
      int missedCount = questionsMissed();

      //Outputting total correct
      System.out.println("Total Correct: " + correctCount); 

      //Outputting total incorrect
      System.out.println("Total Incorrect: " + incorrectCount);

      //Outputting missed questions
      System.out.println("Total missed: " + missed);
   }

   // Determines total correct answers
      public static int totalCorrect()
   {
      int correctCount = 0; 

          for (int x = 0; x < correctAnswers.length; x++)
          {
             if (userAnswers[x].equalsIgnoreCase(correctAnswers[x]))
             {
                correctCount++; 
             }
          }
          return correctCount;
   }

   // Determines total incorrect answers
   public static int totalIncorrect()
       {
          int incorrectCount = 0; 

          for (int x = 0; x < correctAnswers.length; x++)
          {
             if (!userAnswers[x].equalsIgnoreCase(correctAnswers[x]))
             {
                missedCount[incorrectCount] = x; 
                incorrectCount++; 
             }
          }
          return incorrectCount; 
       }

       // Determines total questions missed
       public int[] questionsMissed()
       {
          return missedCount; 
       }

       // Returns if user's answer is valid
       public static boolean isValidAnswer (String answer)
   {
      return "A".equalsIgnoreCase(answer) || 
         "B".equalsIgnoreCase(answer)
         || "C".equalsIgnoreCase(answer) || 
         "D".equalsIgnoreCase(answer); 
   }
}

输出：

DriverLicenseExam.java:48: error: non-static method questionsMissed() cannot be referenced from a static context
      int missedCount = questionsMissed();
                        ^
DriverLicenseExam.java:48: error: incompatible types: int[] cannot be converted to int
      int missedCount = questionsMissed();
                                       ^
DriverLicenseExam.java:65: error: cannot find symbol
          for (int x = 0; x < correctAnswers.length; x++)
                              ^
  symbol:   variable correctAnswers
  location: class DriverLicenseExam
DriverLicenseExam.java:67: error: cannot find symbol
             if (userAnswers[x].equalsIgnoreCase(correctAnswers[x]))
                                                 ^
  symbol:   variable correctAnswers
  location: class DriverLicenseExam
DriverLicenseExam.java:67: error: cannot find symbol
             if (userAnswers[x].equalsIgnoreCase(correctAnswers[x]))
                 ^
  symbol:   variable userAnswers
  location: class DriverLicenseExam
DriverLicenseExam.java:80: error: cannot find symbol
          for (int x = 0; x < correctAnswers.length; x++)
                              ^
  symbol:   variable correctAnswers
  location: class DriverLicenseExam
DriverLicenseExam.java:82: error: cannot find symbol
             if (!userAnswers[x].equalsIgnoreCase(correctAnswers[x]))
                                                  ^
  symbol:   variable correctAnswers
  location: class DriverLicenseExam
DriverLicenseExam.java:82: error: cannot find symbol
             if (!userAnswers[x].equalsIgnoreCase(correctAnswers[x]))
                  ^
  symbol:   variable userAnswers
  location: class DriverLicenseExam
DriverLicenseExam.java:84: error: cannot find symbol
                missed[incorrectCount] = x; 
                ^
  symbol:   variable missed
  location: class DriverLicenseExam
DriverLicenseExam.java:94: error: cannot find symbol
          return missedCount; 
                 ^
  symbol:   variable missedCount
  location: class DriverLicenseExam
10 errors

我遇到了这些错误，不知道如何解决。感谢您的帮助！

Answer 1

有几个建议，我想给你： 1.正如ggorlen在评论部分提到的，不要试图一次写大代码然后测试它。在编写代码时继续测试代码。 2. 使用编辑器，有很多免费的 JAVA 编辑器可以帮助您调试或识别代码中的错误。 3. 请尝试阅读一些基本概念，如作用域、静态关键字、返回类型。

您遇到的错误之一：

DriverLicenseExam.java:48: error: incompatible types: int[] cannot be converted to int
      int missedCount = questionsMissed();

因为您的方法返回一个数组，而您将其捕获到一个 int 变量中。

Answer 2

因为你的参数不是全局的，所以我做了一些修改， 你可以看到：

修复你的三个方法：

    int[] missedCount = questionsMissed(missed);
    int correctCount = totalCorrect(correctAnswers,userAnswers);
    int incorrectCount = totalIncorrect(correctAnswers,userAnswers,missedCount);

import java.util.Scanner;
public class DriverLicenseExam
{

public static void main(String[] args)
{
    // Arrays
    String[] correctAnswers = {"B", "D", "A", "A", "C",
            "A", "B", "A", "C", "D",
            "B", "C", "D", "A", "D",
            "C", "C", "B", "D", "A"};
    String[] userAnswers;
    int[] missed = new int[correctAnswers.length];
    String[] answers = new String[20];
    String answer;

    // User's input
    System.out.println("Enter your answers for the exam here: ");
    Scanner input = new Scanner(System.in);
    for (int x = 0; x < 20; x++)
    {
        do
        {
            System.out.print((x+1) + ": ");
            answer = input.nextLine();
        }
        while (!isValidAnswer(answer));

        answers[x] = answer;
    }

    //Process the user's answers
    userAnswers = new String[answers.length];

    for (int x = 0; x < answers.length; x++)
    {
        userAnswers[x] = answers[x];
    }



    int[] missedCount = questionsMissed(missed);

    //Results
    int correctCount = totalCorrect(correctAnswers,userAnswers);
    int incorrectCount = totalIncorrect(correctAnswers,userAnswers,missedCount);

    //Outputting total correct
    System.out.println("Total Correct: " + correctCount);

    //Outputting total incorrect
    System.out.println("Total Incorrect: " + incorrectCount);

    //Outputting missed questions
    System.out.println("Total missed: " + missed);
}

// Determines total correct answers
public static int totalCorrect(String[] correctAnswers,String[] userAnswers)
{
    int correctCount = 0;

    for (int x = 0; x < correctAnswers.length; x++)
    {
        if (userAnswers[x].equalsIgnoreCase(correctAnswers[x]))
        {
            correctCount++;
        }
    }
    return correctCount;
}

// Determines total incorrect answers
public static int totalIncorrect(String[] correctAnswers,String[] userAnswers,int[] missedCount)
{
    int incorrectCount = 0;

    for (int x = 0; x < correctAnswers.length; x++)
    {
        if (!userAnswers[x].equalsIgnoreCase(correctAnswers[x]))
        {
            missedCount[incorrectCount] = x;
            incorrectCount++;
        }
    }
    return incorrectCount;
}

// Determines total questions missed
public static int[] questionsMissed(int[] missedCount)
{
    return missedCount;
}

// Returns if user's answer is valid
public static boolean isValidAnswer (String answer)
{
    return "A".equalsIgnoreCase(answer) ||
            "B".equalsIgnoreCase(answer)
            || "C".equalsIgnoreCase(answer) ||
            "D".equalsIgnoreCase(answer);
}
}