Java：查找数组中双打的平均值

Question

我正在为Java类简介做作业。 作业的一部分是将文本文件中的双精度读入数组，然后使用其他方法来计算平均值。 到目前为止，我已经将双精度数读入了数组，但是我不确定如何在另一种方法中引用该数组来计算平均值。 我一直在网上搜索，但未找到任何结果，可能是因为我的术语不正确导致我没有相关的答案。 我从netbeans中收到一个错误，指出找不到符号classGrades（因为它仅在main方法中）。我尝试将它定义为全局变量，但这没有用，而且我们还没有学到这些必须有另一种方式来做到这一点。

总结一下：我不知道如何在方法之间引用变量。

这是我的代码

import java.io.File;
import java.util.Arrays;
import java.util.Scanner;

public class GradeChecker {

public static void main(String[] args) {
    // TODO code application logic here
    double[] classGrades = new double[76];
    double classAverage = calculateAverageGrade();


    fillArray(classGrades);
    for (int i = 0; i < classGrades.length; i++) {
        System.out.println(classGrades[i]);
    }
    //System.out.print(Arrays.toString(classGrades));
    System.out.print(classGrades.length);

}
    public static void fillArray(double[] ary) {
    try {
        File arrayInput = new File("ClassGrades.txt");
        Scanner in = new Scanner(arrayInput);
        in.useDelimiter("\r\n");

        int i = 0;
        while (in.hasNextLine()) {
            ary[i++] = in.nextDouble();
        }
        in.close();
    } catch (Exception exception) {
        System.out.println("Error: " + exception.getMessage());
    }
}

    private static double calculateAverageGrade(double[] classGrades) {
    double gradeSum = 0;
    double gradeAverage = 0;
    for (int i = 0.0; i < classGrades.length; i++) {
        gradeSum = gradeSum + classGrades[i];
    }
    gradeAverage = gradeSum/classGrades.length;
    return gradeAverage;
}
}

Answer 1

您可以将数组classGrades传递给该函数：

    double[] classGrades = new double[76];
    double classAverage = calculateAverageGrade(classGrades);

这里：

import java.io.File;
import java.util.Arrays;
import java.util.Scanner;

public class GradeChecker {

    public static void main(String[] args) {
        // TODO code application logic here
        double[] classGrades = new double[76];
        double classAverage = calculateAverageGrade(classGrades);


        fillArray(classGrades);
        for (int i = 0; i < classGrades.length; i++) {
            System.out.println(classGrades[i]);
        }
        //System.out.print(Arrays.toString(classGrades));
        System.out.print(classGrades.length);

    }

    public static void fillArray(double[] ary) {
        try {
            File arrayInput = new File("ClassGrades.txt");
            Scanner in = new Scanner(arrayInput);
            in.useDelimiter("\r\n");

            int i = 0;
            while (in.hasNextLine()) {
                ary[i++] = in.nextDouble();
            }
            in.close();
        } catch (Exception exception) {
            System.out.println("Error: " + exception.getMessage());
        }
    }

    private static double calculateAverageGrade(double[] classGrades) {
        double gradeSum = 0;
        double gradeAverage = 0;
        for (int i = 0; i < classGrades.length; i++) {
            gradeSum = gradeSum + classGrades[i];
        }
        gradeAverage = gradeSum / classGrades.length;
        return gradeAverage;
    }
}

Answer 2

我已经编辑了您的代码。

import java.io.File;
import java.util.Arrays;
import java.util.Scanner;

public class GradeChecker {

    public static void main(String[] args) {
        // TODO code application logic here
        double[] classGrades = new double[76];
        fillArray(classGrades);

        double classAverage = calculateAverageGrade(classGrades);

        for (int i = 0; i < classGrades.length; i++) {
            System.out.println(classGrades[i]);
        }
        //System.out.print(Arrays.toString(classGrades));
        System.out.print(classGrades.length);

    }
    public static void fillArray(double[] ary) {
        try {
            File arrayInput = new File("ClassGrades.txt");
            Scanner in = new Scanner(arrayInput);
            in.useDelimiter("\r\n");

            int i = 0;
            while (in.hasNextLine()) {
                ary[i++] = in.nextDouble();
            }
            in.close();
        } catch (Exception exception) {
            System.out.println("Error: " + exception.getMessage());
        }
    }

    private static double calculateAverageGrade(double[] classGrades) {
        double gradeSum = 0;
        double gradeAverage = 0;
        for (int i = 0; i < classGrades.length; i++) {
            gradeSum = gradeSum + classGrades[i];
        }
        gradeAverage = gradeSum/classGrades.length;
        return gradeAverage;
    }
}

请尝试这个，让我知道

编辑1

• 很多编译问题。
• 找到fillArray之后调用fillArray