java - 为什么我的计数器没有计数，并且我的 ArrayList 没有将新的整数值添加到数组中？

Question

我的问题的主要来源来 self 的方法“add”和数组“mathAnswers”以及计数器“score”。

我正在尝试比较数组值，使它们执行数学函数，然后检查用户输入是否与答案匹配。我还希望将正确的答案添加到数组中，然后打印出该数组以及验证用户分数的计数器。

我遇到了一个问题，我的计数器没有递增，我的值没有输入到我的数组中，并且所有内容都保持为 0。这是我的代码。

    import java.util.Scanner;
import java.util.ArrayList;
public class Program7 {

    public static void main(String[] args) {
        int [] mathQuizLeft = {
                8,  //0
                14, //1
                16, //2
                8,  //3
                17, //4
                5,  //5
                27, //6
                4,  //7
                20, //8
                13, //9
        };

        int [] mathQuizRight = {
                13, //0
                12, //1
                4,  //2
                18, //3
                4,  //4
                4,  //5
                9,  //6
                7,  //7
                4,  //8
                4,  //9
        };


        Scanner scanner = new Scanner(System.in);

        double userAns = 0;
        double answer = 6;

        System.out.println("Welcome to the 3rd Grade Math Quiz. \n");
        System.out.println("The Quiz begins now: \n"
                + "1. 8 - 13\n2. 14 + 12\n3. 16 / 4\n4. 8 + 18\n5. 17 % 4\n6. 5 x 4\n"
                + "7. 27 / 9\n8. 4 - 7\n9. 20 x 4\n10. 13 - 4");

        for(int i = 0; i <= 10; i++) {
            if (i < 10) {
                System.out.printf("%d. ", (i + 1));
                userAns = Double.valueOf(scanner.nextDouble());
                add(mathQuizLeft, mathQuizRight, i, answer, userAns);
            }
            else {
                add(mathQuizLeft, mathQuizRight, i, answer, userAns);
            }
        }
    }



    public static void add(int[] array1, int[] array2, int i, double answer, double userAns) {
        ArrayList<Integer> mathAnswers = new ArrayList<>(); //for storing functions

        int score = 0;

        if (i == 1 || i == 3) { //addition
            answer = array1[i] + array2[i];
            if (userAns == answer) {
                score++;
                mathAnswers.add(i);
            }
        } else if (i == 0 || i == 7 || i == 9) { //subtraction
            answer = array1[i] - array2[i];
            if (userAns == answer) {
                score++;
                mathAnswers.add(i);
            }
        } else if (i == 5 || i == 8) { //multiplication
            answer = array1[i] - array2[i];
            if (userAns == answer) {
                score++;
                mathAnswers.add(i);
            }
        } else if (i == 2 || i == 6) { //multiplication
            answer = array1[i] - array2[i];
            if (userAns == answer) {
                score++;
                mathAnswers.add(i);
            }
        } else if (i == 4) { //multiplication
            answer = array1[i] - array2[i];
            if (userAns == answer) {
                score++;
                mathAnswers.add(i);
            }
        } else if (i == 10) {
            for (double array: mathAnswers) {
                System.out.println(array);
            }
            System.out.println(score);
        }
    }
}

Answer 1

您的错误在于 add() 方法。您在每个正确答案后计算分数并将 i 添加到 ArrayList，但您并没有保护 arraylist 和分数。您必须将 ArrayList 和分数声明为全局，或者必须返回它并将其保存在 main() 方法中。

public class Program7 {
  private static int score = 0;
  private static ArrayList<Integer> mathAnswers = new ArrayList<>();

  public static void main(String[] args) {
    ...
  }

  public static void add(...) {
    if(...) {
      ...
    }
    ...
  }
}