How to successfully add up 2d matrices?

Question

Sorry guys, I'm a beginner in Java and I was wondering if I could get some help.

import java.util.Scanner;
import java.util. Arrays;

public class Matrices_Lab
{
    public static int sumMat( int[][] matty )
    {
      //code

}

   public static void main(String[] args) 
   {
       int[][] mat = {{2,3,4},{55,66,77},{22,11}};

       System.out.println( sumMat( mat ) );

   }
}

the //code part is what I have to fill in. This is what I have so far but it is not working.

 int[] finished_array;
       for(int i=0; i<matty.length;i++){
           for(int j=0; j<matty.length;j++){
             int[] temp+=  matty[j][i];

             finished_array=temp;

Can someone help me out? How do I fill in the function to successfully make it work?

In the second for loop, you need to use i index: `for(int j=0; j — B.J. Smegma, Aug 18 '14 at 15:22
Related / Possible Duplicate of http://stackoverflow.com/questions/15638550/finding-sum-of-two-dimensional-array-java — Unihedron, Aug 25 '14 at 04:48
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Adam · Answer 1 · 2014-08-18T15:28:58.287

Get your first matrix, and your second matrix. Think, how do you add up matrices...you need the same (row, column) point for each of them. Then, loop through each point in the matrix and do it.

Rows and Columns should be given, use your own values

NOTE: This obviously works for 2 matrices. Make a function and just keep looping through making all the matrices you want.

Ex.

private void makeMatrix()
{
    while("condition")
       //code below for matrix
}

       //First matrix
       for (int i = 0; i < rows; i++) {
           for (int j = 0; j < columns; j++) {
               a[i][j] = foo.nextInt();
           }
       }
       //Second Matrix
       for (int i = 0; i < rows; i++) {
           for (int j = 0; j < columns; j++) {
               b[i][j] = foo.nextInt();
           }
       }
       int[][] c = new int[rows][columns];
       for (int i = 0; i < rows; i++) {
           for (int j = 0; j < columns; j++) {
               c[i][j] = a[i][j] + b[i][j];
           }
       }
       //Sum of the 2 matrixes
       for (int i = 0; i < rows; i++) {
           for (int j = 0; j < columns; j++) {
               System.out.print(c[i][j] + " ");
           }
           System.out.println();

How to successfully add up 2d matrices?

1 Answers1