如何在 2D Arraylist 中找到最大值/秒？

Question

I'm trying to rewrite an old program by using Arraylists instead of just arrays. The program was a database of the top 5 video game sales in 2017, and one of the methods the program does is finding the maximum values per location (4 locations in all: NA, EU, JP, & Other Sales).

(Note: There are 5 columns of sales in all (NA, EU, JP, Other Sales, Global Sales), and I only wanted the method to find the maximum values in the first four columns.)

These are snippets of the 2D array and its corresponding method for finding the maximum values:

double[][] Sales ={ {41.49,29.02,3.77,8.46,82.74},{29.08,3.58,6.81,0.77,40.24},
        {15.85,12.88,3.79,3.31,35.83},{15.75,11.01,3.28,2.96,33},
        {11.27,8.89,10.22,1,31.38} };


// maximum value
public static void hiSales(double[][] sales) {
    double max1;
    double[] max = new double[sales.length];
    for(int j=0; j<sales[0].length-1;j++) { //WILL WORK AS LONG AS IT IS SQUARE MATRIX
        
        for (int i = 0; i < sales.length; i++) {
            max1 = sales[0][j];
            if (sales[i][j] > max1) {
                max1 = sales[i][j];
            }
            if (i == sales.length - 1) {
                max[j] = max1;
            }
        }
    }
    System.out.println("\n                | HIGHEST SALES PER LOCATION |");
    System.out.println("\n | NA Sales |    | EU Sales |    | JP Sales |   "
            + "| Other Sales |   \n");
    System.out.println("— — — — — — — — — — — — — — — — — — — — — — — — — — — — — — — —\n");
    System.out.print("     ");
    for(int i=0; i<max.length-1; i++) {
        System.out.print(max[i] + "\t");
        System.out.print("     ");
    } 
    System.out.println("\n");
    System.out.println("— — — — — — — — — — — — — — — — — — — — — — — — — — — — — — — —");
}

Now, I've converted the 2D array into a 2D Arraylist, and the method cannot function anymore, which is the problem I would like to address.

This is the new 2D Arraylist I've converted:

ArrayList<VGSdata> sales = new ArrayList<>();
VGSdata wii = new VGSdata(41.49,29.02,3.77,8.46,82.74);
VGSdata bros = new VGSdata(29.08,3.58,6.81,0.77,40.24);
VGSdata kart = new VGSdata(15.85,12.88,3.79,3.31,35.83);
VGSdata res = new VGSdata(15.75,11.01,3.28,2.96,33);
VGSdata prb = new VGSdata(11.27,8.89,10.22,1,31.38);
    
sales.add(wii);
sales.add(bros);
sales.add(kart);
sales.add(res);
sales.add(prb);

So.. how will the method be rewritten in order for it to utilize the data in the ArrayList while still performing the same function?

Answer 1

If you do not want to rewrite the hiSales method then you could create a 2d array from the arraylist and then pass it on to the hiSales method.

double[][] dataArray = new double[sales.size()][4];
int i=0;
for(VGSdata data : sales) {
    dataArray[i][0] = data.displayNA();
    dataArray[i][1] = data.displayEU();
    dataArray[i][2] = data.displayJP();
    dataArray[i][3] = data.displayOS();

    i++;
}

// now invoke hiSales
hiSales(dataArray);