Thread: Hey guys I need some help

import java.util.Scanner;
public class Matrix {
 
 
public static void main(String[] args) {
 
Scanner scan = new Scanner(System.in);
 
double[][] matrix = new double[3][4];
System.out.println("Enter a " + matrix.length + "-by-" + matrix[0].length + " matrix row by row:"  );
 
for (int row = 0; row < matrix.length; row++) {
for (int column = 0; column < matrix[row].length; column++) {
 
 
matrix[row][column] = scan.nextDouble();
System.out.print(matrix[row][column] + " ");
}
System.out.println();
}                        
for (int i = 0; i < 4; i++) {
System.out.println("Sum of column " + i + " is " + sumColumn(matrix, i));
}
}
 
public static double sumColumn(double[][] m, int columnIndex) {
double sum = 0;
for (int i = 0; i < m.length; i++) {
sum += m[i][columnIndex];
}
return sum;
}
}

what did I do wrong?