Question

我创建此代码来平均测试分数，但是我将每个学生test1，test2，test3等放在一个数组中。现在我怎么能得到一个测试的测试分数的总体平均值（例如q1在数组索引0中，但它们是8个不同的q1。我如何获得它们的平均值？）

import java.io.File;
import java.io.IOException;
import java.util.*;

public class Project3 {

    public static void main(String[] args) throws IOException  {



        ReadFile r = new ReadFile();
        r.openFile();
        r.readFile();
        r.closeFile();

-

import java.io.*;
import java.lang.*;
import java.util.*;

public class Grades {

    private  Formatter x;
    //Formatter variable- output string to file


    public void openFile(){
        //method to open file
        try{
            x = new Formatter("grades.txt");


        }
        catch(Exception e){
            System.out.println("Could not find file.");
        }
    }

        public void addRecords(){
        x.format("%d",8);
        x.format(" %s %s, %d, %d, %d, %d, %d, %d, %d", " Thui", "Bhu", 100, 90, 80, 100, 89, 99, 88);
        x.format(" %s %s, %d, %d, %d, %d, %d, %d, %d", "\n ArianaB", "Smith", 90, 90, 100, 100, 99, 100, 95);
        x.format(" %s %s, %d, %d, %d, %d, %d, %d, %d", "\n Emily", "Gonzales", 100, 90, 100, 70, 78, 78, 80);
        x.format(" %s %s, %d, %d, %d, %d, %d, %d, %d", "\n Jenifer", "L", 80, 90, 90, 100, 89, 99, 85);
        x.format(" %s %s, %d, %d, %d, %d, %d, %d, %d", "\n Maria", "Jones", 65, 72, 77, 68, 62, 70, 65);
        x.format(" %s %s, %d, %d, %d, %d, %d, %d, %d", "\n Bill", "Gates", 60, 54, 38, 62, 65, 60, 50);
        x.format(" %s %s, %d, %d, %d, %d, %d, %d, %d", "\n Escobar", "Morris", 83, 77, 88, 76, 79, 72, 76  );
        x.format(" %s %s, %d, %d, %d, %d, %d, %d, %d", "\n Anne", "Latner", 80, 90, 85, 95, 90, 95, 90  );


        }
        public void closeFile(){
            x.close();
        }
        //



}

-

import java.io.*;
import java.util.InputMismatchException;

import java.util.*;
public class ReadFile {

private Scanner x;

        public void openFile(){
    try{
        x = new Scanner (new File ("grades.txt"));
    }
    catch(Exception e){
        System.out.println("could not find file");
    }}



public void createFile()throws IOException {


    try{
        File file = new File("grades.txt");
        Scanner s = new Scanner(file);




    while(s.hasNext()){

        {   

        double q1average = 0.0, q2average = 0.0, q3average = 0.0, q4average = 0.0;
        double proji = 0.0, projii =0.0, projiii = 0.0;
        double q1sum = 0.0, q2sum = 0.0, q3sum = 0.0, q4sum = 0.0;
        double proji_sum = 0.0, projii_sum = 0.0, projiii_sum =0.0;
        while(s.hasNext()) {
            String[] split = s.nextLine().split(", ");

            q1sum += Double.parseDouble(split[1]); // add all first grades
            q1average++;

            q2sum += Double.parseDouble(split[2]); // add all first grades
            q2average++;

            q3sum += Double.parseDouble(split[3]); // add all first grades
            q3average++;

            q4sum += Double.parseDouble(split[4]); // add all first grades
            q4average++;

            proji_sum += Double.parseDouble(split[5]); // add all first grades
            proji++;

            projii_sum += Double.parseDouble(split[6]); // add all first grades
            projii++;

            projiii_sum += Double.parseDouble(split[7]); // add all first grades
            projiii++;
            int maxq1 =0;
            if(Double.parseDouble(split[1]) > maxq1) 
                maxq1 = (int) Double.parseDouble(split[1]);
            System.out.println(maxq1);
        }

        double q1_average =  (q1sum/q1average);
        double q2_average = (q2sum / q2average);
        double q3_average = (q3sum / q3average);
        double q4_average = (q4sum / q4average);
        double p1_average = (proji_sum/proji);
        double p2_average = (projii_sum/projii);
        double p3_average = (projiii_sum/projiii);
    }



    }}catch(Exception e){
        e.printStackTrace();
    }



}
public void closeFile(){
    x.close();
}
}

Answer 1

与获得纸面平均值的方式相同：添加所有单独的测试分数并除以总数。因此，创建一个临时变量，然后在循环中，将各个测试分数相加，除以循环后的学生总数。

Answer 2

这不是很好的方法，但它应该工作。因此，您的数组为split[]，它存储由,（逗号）拆分的所有数据。因此，如果您注意到，如果您向第一位学生+8 index添加q（例如q1存储在split[1]中，那么+8，第二{{1} }} Student将存储在q1）中，您将获得第二个学生q。所以可以这样做：

split[9]

你可以和其他人一起做q。但正如我所说，这是样板代码。

Answer 3

基本上你拥有的是一个多维数组。您在多行（“列”）上有多个测试分数（“行”）。你需要将每一行放在某处，以便以后再调用它们。

你可以做这样简单的事情：

double grades = 0.0;
double sum = 0.0;
while(s.hasNext()) {
    String[] split = s.nextLine().split(", ");

    sum += Double.parseDouble(split[1]); // add all first grades
    grades++;
}
System.out.println(sum / grades);

或更复杂的事情：

List<ArrayList<String>> allGrades = new ArrayList<ArrayList<String>>();
while(s.hasNext()) {
    allGrades.add(Arrays.asList(s.nextLine().split(", ")));
}

StringBuilder results = new StringBuilder();
int cols = allGrades.get(0).size();
for(int c = 1; ;) { // outer for every test

    double sum = 0.0;
    double count = 0.0;
    double max = 0.0;
    for(int r = 0; r < allGrades.size(); r++) { // inner for every person
        count++;
        double grade = Double.parseDouble(allGrades.get(r).get(c));
        sum += grade;
        if(grade > max) {
            max = grade;
        }
    }

    results.append("[test ");
    results.append(c);
    results.append(": avg = ");
    results.append(sum / count);
    results.append(", max = ");
    results.append(max);
    results.append(']');

    if(++c < cols) { // fence post logic...
        results.append(", ");
    } else {
        break;
    }
}

System.out.println(results);

或者也许是这样：

double[] avgs = new double[7];
double count = 0.0;
while(s.hasNext()) {
    String[] split = s.nextLine().split(", ");

    for(int i = 0, k = 1; k < split.length; i++, k++) {
        avgs[i] += Double.parseDouble(split[k]);
    }

    count++;
}

for(int i = 0; i < avgs.length; i++) {
    System.out.println("test avg " + (i + 1) + ": " + (avgs[i] / count));
}

文件阅读平均值

3 个答案: