从文本文件创建二维阵列并查找平均值

Question

我正试图从文本文件中的数字创建一个2D数组，该数组可以打印出来，并可以找到每列的平均值。注意：在"int行"one_answers"int列"上，我收到一个错误，说"类型不匹配：无法从java.lang.String转换为int"。如有任何反馈，我们将不胜感激。

示例文本文件：

3

4

6 4 2 12

3 5 6 0

11 0 3 0

输出示例：

分数数组：

[6，4，2，12]

[3,5,6,0]

[11,0,3,0]

每次作业平均得分：

作业#1平均值：6.66666666666

作业#2平均：9.0

作业#3平均值：3.66666666666

作业#4平均：4.0

import java.util.Scanner;
import java.io.File;  
import java.io.FileNotFoundException; 
import java.util.Arrays;
public class Scores {
public static void main(String[] args) throws FileNotFoundException {
Scanner keyboard = new Scanner(System.in);
System.out.println("What is the name of the file containing the scores?");
String fileName = keyboard.nextLine();
Scanner fileScan = new Scanner(new File(fileName));
//TODO: read in the values for the number of students and number of assignments using the Scanner on the file
//TODO: create a 2-D to store all the scores and read them all in using the Scanner on the file
int rows = fileScan.nextLine();
int columns = fileScan.nextLine();
int [][] myArray = new int[rows][columns];
while(fileScan.hasNextLine()) {
for (int i=0; i<myArray.length; i++) {
String[] line = fileScan.nextLine().trim().split(" ");
for (int j=0; j<line.length; j++) {
myArray[i][j] = Integer.parseInt(line[j]);
}
}
}

System.out.println("Array of scores:");
//TODO: print the entire array, row by row, using Arrays.toString()
System.out.println(Arrays.deepToString(myArray));
System.out.println("Average score of each assignment:");
//TODO: compute and print the average on each assignment
double total=0;
int totallength,assignment;
for(int i=0;i<myArray.length;i++) {
for(int j=0;j<myArray[i].length;j++) {
total+=myArray[i][j];
totallength++;
System.out.println("Assignment #" + assignment++ + " Average: " + (total/totallength));
}
}
fileScan.close(); 
}
}

Answer 1

Scanner.nextLine((返回一个String，而不是int。您可以尝试类似int rows = fileScan.nextInt()或int rows = Integer.parseInt(fileScan.nextLine());的方法

Answer 2

您的问题是从文件中读取rows和columns时它们是字符串。您需要将它们转换为整数，然后才能将它们用作数组索引。所以这样做吧：

int rows = Integer.parseInt(fileScan.nextLine());
int columns = Integer.parseInt(fileScan.nextLine());