求二维数组java的总和

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我正在一个项目中，我必须读取文件并将内容输入2D数组.然后，我必须对每一行，每一列以及矩阵的周长求和.到目前为止，除外围功能外，我一切正常.我正在尝试为两个外部列的顶行，底行和中间创建单独的for循环.

I am working on a project where I have to read a file and enter the content into a 2D array. Then I have to sum each row, each column, and the perimeter of the matrix. I have everything working so far except the perimeter. I am trying to create separate for loops for the top row, bottom row, and middle of the two outside columns.

矩阵文件如下:

1 2 3 4 2 4 6 8 2 4 6 8 3 2 3 4

因此，周长总计应为42. 现在，我可以成功地将第一行和最后一行添加为等于22.但是，当我将列添加到总数中时，我得到32.

Therefore the perimeter should add up to 42. Right now I can successfully add the first row and the last row to equal 22. However, when I add the columns to that total I get 32.

这是代码:

import java.util.*; // Scanner class import java.io.*; // File class public class Lab10 { static public void main( String [ ] args ) throws Exception { if ( args.length != 1 ) { System.out.println("Error -- usage is: java Lab10 matdataN.txt"); System.exit( 0 ); } //Requirement #1: first int value: # of rows, second int value: # of cols File newFile = new File(args[0]); Scanner in = new Scanner(newFile); int numRows = in.nextInt(); int numCols = in.nextInt(); //Requirement #2: declare two-d array of ints int[][] matrix; matrix = new int[numRows][numCols]; //Requirement #3 & 4: read file one line at a time (nested for loops //and nextInt()) and print for (int i = 0; i < numRows; i++) { for (int j = 0; j < numCols; j++) { matrix[i][j] = in.nextInt(); System.out.print(matrix[i][j]+ " "); } System.out.println(); } //Requirement #5: traverse each row and sum the values and display the sums int rowTotal = 0; for (int i = 0; i < numRows; i++) { rowTotal = 0; for (int j = 0; j < numCols; j++) { rowTotal += matrix[i][j]; } System.out.println("Sum for row = " + rowTotal); } //Requirement #6: traverse each column and sum the values and display the sums int colTotal = 0; for (int i = 0; i < numRows; i++) { colTotal = 0; for (int j = 0; j < numCols; j++) { colTotal += matrix[j][i]; } System.out.println("Sum for col = " + colTotal); } //Requirement #7: traverse the perimeter and sum the values and display the sum //sum bottom row matrix int perTotal = 0; for (int i = (numRows-1); i < numRows; i++) { perTotal = 0; for (int j = 0; j < numCols; j++) { perTotal += matrix[i][j]; } } //sum + top row matrix for (int i = 0; i < numRows - (numRows-1); i++) { for (int j = 0; j < numCols; j++) { perTotal += matrix[i][j]; } System.out.println("Sum of perimeter = " + perTotal); } // sum + first col middle for (int i = 1; i < (numRows-1); i++) { for (int j = 0; j < numCols - (numCols-1); j++) { perTotal += matrix[j][i]; } System.out.println("Sum = " + perTotal); } // sum + last col middle for (int i = 1; i < (numRows-1); i++) { for (int j = (numCols-1); j < numCols; j++) { perTotal += matrix[j][i]; } System.out.println(perTotal); } }

如果有人能帮助我将第一列和最后一列的总和设为2 + 2和8 + 8，我将非常感激.或者，如果您有一种更好的方法来寻找周长.预先感谢！

I would be hugeeeeeely appreciative if anyone could help me total the middle of the first and last column (should be 2+2 and 8+8). Or if you have an altogether better way of finding the perimeter. Thanks in advance!

推荐答案

我建议您这样做:

int perTotal = 0; // top and bottom row for (int c = 0; c < numCols; c++) perTotal += matrix[0][c] + matrix[numRows-1][c]; // left and right column for (int r = 1; r < numRows-1; r++) perTotal += matrix[r][0] + matrix[r][numCols-1]; // output System.out.println("Perimeter=" + perTotal);