2D阵列的列和行之和 [英] Sum of columns and rows of 2D array
问题描述
我已经在向上和向下搜索以解决我的问题，但是似乎没有任何效果。一个特定的参考-此和此，尤其是此。但是，无论我如何实现它们，我都会收到一个OutOfBoundsError，这是我无法理解的。
I've searched up and down for the fix to my issue, but none seem to work. One particular reference-- this and this, and especially this. However, no matter how I implement them, I receive an OutOfBoundsError, which I can't understand.
该程序对于某堂课来说是额外的功劳。实际上，这非常简单-
The program is extra credit for a class. In truth, it is very simple--
程序说明：使用二维数组可以解决以下问题。一个公司有四个销售人员（1-4），他们销售五个不同的产品（1-5）。每天一次，每个销售员都会针对每种不同类型的产品传递一张纸条。每张纸条包含：
Program Description: Use a two dimensional array to solve the following problem. A company has four sales persons (1 to 4) who sell five different products (1 to 5). Once a day, each salesperson passes in a slip for each different type of product sold. Each slip contains:
销售人员编号
产品编号
当天销售的产品的总价值
The sales persons number
The product number
The total dollar value of that product sold that day
因此，每个销售员每天传递0到5个销售单。假设上个月所有票据的信息均可用。每个数据行包含3个数字（销售人员编号，产品编号，销售量）。
Thus, each salesperson passes in between 0 and 5 sales slips per day. Assume that the information from all of the slips for last month is available. Each data line contains 3 numbers (the sales person number, product number, sales).
编写一个程序，该程序将读取上个月销售的所有这些信息，并汇总销售人员的总销售额
Write a program that will read all this information for last month’s sales, and summarize the total sales by salesperson by product.
提供的数据：
1 2 121.77
1 4 253.66
1 5 184.22
1 1 97.55
2 1 152.44
2 2 104.53
2 4 189.97
2 5 247.88
3 5 235.87
3 4 301.33
3 3 122.15
3 2 301.00
3 1 97.55
4 1 125.66
4 2 315.88
4 4 200.10
4 3 231.45
仅在尝试计算列时才会出现错误。我的行工作；无论我如何更改数组的行或列中的for循环或任何indes，它都行不通。首先，我分别计算了行数，然后对列求和，这也不起作用。
The error only comes when it tries to calculate the columns. My rows work; no matter how I change the for-loop or any of the indeces in the row or column of the array, it doesn't work. I at first had my rows calculated separately, then my column sums, and it didn't work either. There is something that I'm missing that I'm clearly overlooking.
这是我的代码：
import java.io.File;
import java.io.FileNotFoundException;
import java.text.DecimalFormat;
import java.util.Scanner;
public class prog480u {
static Scanner inFile = null;
public static void main(String[] args) {
try {
// create scanner to read file
inFile = new Scanner(new File ("prog480u.dat"));
} catch (FileNotFoundException e) {
System.out.println("File not found!");
System.exit(0);
}
// make the array
int x = 0;
int y = 0;
double[][] profits = new double[4][5];
while (inFile.hasNext()) {
x = inFile.nextInt(); // use sales numbers as coordinates
y = inFile.nextInt();
profits[x - 1][y - 1] = inFile.nextDouble();
}
// check if it's okay
System.out.println("");
double[][] columnProfits = sums(profits);
for (int a = 0; a < columnProfits.length; a++) {
System.out.print((a+1) + "\t");
for (int b = 0; b < columnProfits[a].length; b++) {
System.out.print(columnProfits[a][b] + "\t");
}
System.out.println("");
}
double[] bottomRow = columnSums(columnProfits);
for (int a = 0; a < bottomRow.length; a++) {
System.out.print("Total:" + bottomRow + "\t");
}
}
public static double[][] sums (double[][] q) {
double[][] array = new double[5][6];
array = q;
double sum = 0;
for (int a = 0; a < array.length; a++) {
for (int b = 0; b < array[0].length; b ++) {
sum += array[a][b]; // add everything in the row
}
array[a][4] = sum; // set that row to the last column
sum = 0; // reset sum to 0
}
return array;
}
public static double[] columnSums (double[][]q) {
double[][] array = new double[5][6];
array = q;
double sum2 = 0;
double[] columns = new double [5];
for (int a = 0; a < array.length; a++) {
for (int b = 0; b < array[0].length; b ++) {
sum2 += array[b][a];
columns[b] = sum2;
}
sum2 = 0; // reset sum to 0
}
return columns;
}
}
非常感谢您的宝贵时间。我感觉我的程序快要运行了，但是这个小错误把我逼到了极限。
Thank you very much for your time. I have a feeling my program is close to working, but this small mistake is pushing me over the edge.
推荐答案
代码（我做了一点清理）：
Here's the working code (I cleaned it up a bit):
您非常接近，您只需要在for循环中交换最大索引。这就是为什么您得到 java.lang.ArrayIndexOutOfBoundsException
You were very close, you just needed to swap your max indicies in the for loops. That's why you were getting a java.lang.ArrayIndexOutOfBoundsException
public static double[] columnSums(double[][] q)
{
double[][] array = q;
double[] columns = new double[5];
for (int a = 0; a < array[0].length; a++)
{
for (int b = 0; b < array.length; b++)
{
columns[a] += array[b][a];
}
}
return columns;
}
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