Java Matrices Matrices

Ce programme ajoute deux matrices 3x3. Il compile et s'exécute, mais la sortie, au lieu d'être:

1.0  2.0  3.0       0.0  2.0  4.0       1.0  4.0  7.0
4.0  5.0  6.0   +   1.0  4.5  2.2   =   5.0  9.5  8.2
7.0  8.0  9.0       1.1  4.3  5.2       8.1  12.3 14.2

Il produit:

1.0  2.0  3.0       0.0  2.0  4.0       0.0  0.0  0.0
4.0  5.0  6.0   +   1.0  4.5  2.2   =   0.0  0.0  0.0
7.0  8.0  9.0       1.1  4.3  5.2       0.0  0.0  0.0

Je ne suis pas sûr pourquoi, la sortie s'affiche comme tous les zéros? Les mathématiques dans le programme "semble" le droit de me... il y a une chose qui me manque ici?

import java.util.Scanner;
public class AddMatrices{
public static void main(String[] args){
Scanner input = new Scanner(System.in);
int N = 3;
//get the users input and store it in the two arrays
System.out.println("\nEnter matrix1: \n");
//declare 2 arrays with the appropriate number of rows and columns in 
//them to store the numbers in each matrix.
//this is the first one.
double[][] matrix1 = new double[N][N];
for (int i = 0; i < matrix1.length; i++) {
for (int j = 0; j < matrix1[i].length; j++) {
matrix1[i][j] = input.nextDouble();
}
}
//get the users input and store it in the two arrays
System.out.println("\nEnter matrix2: \n");
//declare 2 arrays with the appropriate number of rows and columns in 
//them to store the numbers in each matrix.
//this is the second one.
double[][] matrix2 = new double[3][3];
for (int i = 0; i < matrix1.length; i++) {
for (int j = 0; j < matrix1[i].length; j++) {
matrix2[i][j] = input.nextDouble();
}
}
//call the addMatrix method and pass it the two arrays
double[][] resultingMatrix = addMatrix(matrix1, matrix2);
System.out.println("The addition of the matrices is ");
}//end of main method
//write the addMatrix method to add the two matrices and display the result
public static double[][] addMatrix(double[][] m1, double[][] m2){
double[][] result = new double[m1.length][m1[0].length];
for (int i = 0; i < result.length; i++) {
for (int j = 0; j < result[0].length; j++){
m1[i][j] += m2[i][j];
}
}
for (int i = 0; i < m1.length; i++) {
char plus = '+';
for (int j = 0; j < m1[0].length; j++) {
System.out.print("  " + m1[i][j]);
}
if (i == m1.length / 2)
System.out.print("  " + plus + "  ");
else {
System.out.print("  ");
}
for (int j = 0; j < m2[0].length; j++) {
System.out.print("  " + m2[i][j]);
}
if (i == m1.length / 2)
System.out.print("  =  ");
else {
System.out.print("  ");
}
for (int j = 0; j < result[0].length; j++) {
System.out.print("  " + result[i][j]);
}
System.out.println();
}
return result;
}//end of add matrices
}//end of class