java - 从文本文件创建二维数组并查找平均值

Question

我正在尝试从文本文件中的数字创建一个二维数组，可以打印该数组并找到每列的平均值。注意:我收到一条错误消息，指出“int rows”和“int columns”上的“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

示例输出:

分数数组:

[6,4,2,12]

[3,5,6,0]

[11, 0, 3, 0]

每项作业的平均分:

作业 #1 平均值:6.66666666666

作业 #2 平均分:9.0

作业 #3 平均值:3.66666666666

作业 #4 平均分: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() 返回一个字符串，而不是一个整数。您可以尝试类似 int rows = fileScan.nextInt() 或 int rows = Integer.parseInt(fileScan.nextLine());