你如何使用一种方法来计算成绩的1个数组参数并返回数组的总数？

Question

我的作业要求我编写一个 Java 程序。我没有得到完全正确的东西。

基本上，我必须创建一个 Java 方法，让用户输入 x 数量的成绩（用户选择），将成绩存储在数组中，然后将成绩添加到数组中以在 main 方法中调用。

这是我的代码：

import java.util.Scanner;

public class Sample {

    public static void main(String[] args) {
        Scanner keyboard = new Scanner(System.in);

        System.out.println("Hello Drews, how many total grades do you want to process?");
        int numberOfGrades = keyboard.nextInt();

        int [] storeGrades = new int[numberOfGrades];
    }

    public static int getTotalScore(int numberOfGrades[]) {
        Scanner keyboard = new Scanner(System.in);
        int getTotalScore;
        int []storeGrades;

        for (int i = 0; i < getTotalScore; i++) {
            System.out.println("Please enter grade " + (i + 1) + ": ");
            int userGradeNumbers = keyboard.nextInt();
            storeGrades[i] = userGradeNumbers;
            sum += userGradeNumbers;
        }
    }
}

我在“sum”处收到一个错误，它没有被解析为变量？它不会让我在 for 循环中初始化 sum，也不会让 getTotalScore 方法初始化。为什么不呢？

Answer 1

首先，获取成绩。然后调用方法获取sum。在循环之前声明sum 并将其初始化为0。之后退还。喜欢，

public static void main(String[] args) {
    Scanner keyboard = new Scanner(System.in);
    System.out.println("Hello Drews, how many total grades do you want to process?");
    int numberOfGrades = keyboard.nextInt();
    int[] storeGrades = new int[numberOfGrades];
    for (int i = 0; i < numberOfGrades; i++) {
        System.out.println("Please enter grade " + (i + 1) + ": ");
        storeGrades[i] = keyboard.nextInt();
    }
    System.out.println(getTotalScore(storeGrades));
}

public static int getTotalScore(int[] storeGrades) {
    int sum = 0;
    for (int i = 0; i < storeGrades.length; i++) {
        sum += storeGrades[i];
    }
    return sum;
}

Answer 2

您的代码有正确的意图，但有些事情的顺序有点不对劲，而且目前存在语法问题。

我主张将您的代码拆分为两种方法（除非根据分配明确禁止您这样做）。一种从用户那里获取成绩的方法，另一种方法是对成绩求和。这样做的原因是您最终尝试同时存储和汇总成绩（这在技术上更有效），但这并没有教您如何通过迭代数组来计算运行总数（很可能是本课的重点）。

我要指出的另一件事（这可能超出了您现在在课程中的位置），即当您使用扫描仪时，您需要验证用户是否输入了您认为的内容我打字了。您希望用户输入一个数字，然后他们输入“Avocado”，这是完全合理的。因为Java是强类型的，这会导致你的程序抛出异常并崩溃。我已经添加了一些基本的输入验证作为如何做到这一点的示例；总体思路是：

1) 检查 Scanner 是否有一个 int 2）如果没有int，请用户再试一次 3）否则，它有一个 int ，你可以继续。存储值。

关于扫描仪的最后一件事。 记得关闭它们！如果不这样做，您可能会在扫描程序继续运行时导致内存泄漏。

以下是我将如何修改您的代码以执行您想要的操作。如果有什么不明白的地方给我留言，我会进一步解释。我将 cmets 留在内联，因为我认为这更容易消化！

package executor;

import java.util.Scanner;

public class StudentGrades {

    public static void main(String[] args) {
        Scanner keyboard = new Scanner(System.in);

        // Initial prompt to the user
        System.out.println("Hello Drews, how many total grades do you want to process?");

        // This loop validates that the user has actually entered an integer, and prevents
        // an InputMismatchException from being thrown and blowing up the program.
        int numberOfGrades = 0;
        while (!keyboard.hasNextInt()) {
            System.out.println("Sorry, please enter a valid number!");
            keyboard.next();
        }

        // If the program makes it through the while loop, we know that the Scanner has an int, and can assign it.
        numberOfGrades = keyboard.nextInt();

        // Creating the array using the method getGrades().
        int[] storedGrades = getGrades(numberOfGrades, keyboard);

        // Calculating the total score using the method getTotalScore().
        int totalScore = getTotalScore(storedGrades);

        System.out.println("Total Score is: " + totalScore);
        keyboard.close();
    }

    /**
     * Asks the user to provide a number of grades they wish to sum.
     * @param numberOfGrades the total number of grades that will be requested from the user.
     * @param keyboard the scanner that the user will use to provide the grades.
     * @return the summed grades as an int.
     */
    public static int[] getGrades(int numberOfGrades, Scanner keyboard) {
        int[] grades = new int[numberOfGrades];

        // Asking the user i number of times, to enter a grade to store.
        for (int i = 0; i < numberOfGrades; i++) {
            System.out.println("Please enter grade " + (i + 1) + ":");

            // More input validation to ensure the user can't store "Cat."
            while (!keyboard.hasNextInt()) {
                System.out.println("Sorry, please enter a valid number!");
                keyboard.next();
            }

            int userEnteredGrade = keyboard.nextInt();

            // Storing the user's entry.
            grades[i] = userEnteredGrade;
        }
        return grades;
    }

    /**
     * Sums all of the grades stored within an integer array.
     * @param storedGrades the grades to be summed.
     * @return the total value of summed grades.
     */
    public static int getTotalScore(int[] storedGrades) {
        int totalScore = 0;
        for (int i = 0; i < storedGrades.length; i++) {
            totalScore += storedGrades[i];
        }
        return totalScore;
    }
}