# Sum of row in 2d array java – Java Program to Find the Sum of Each Row and Each Column of a Matrix

Sum of row in 2d array java: In the previous article, we have discussed Java Program to Check Whether a Given Matrix is an Identity Matrix

In this article we are going to see how we can write a program to find the sum of each row and column of a matrix in JAVA language.

## Java Program to Find the Sum of Each Row and Each Column of a Matrix

A 3*3 Matrix is having 3 rows and 3 columns where this 3*3 represents the dimension of the matrix. Means there are 3*3 i.e. total 9 elements in a 3*3 Matrix.

Let’s understand it in more simpler way.

                   | A00   A01   A02 |
Matrix A =  | A10   A11   A12 |
| A20   A21   A22 | 3*3
• Matrix A represents a 3*3 matrix.
• A‘ represents the matrix element
• Aij‘ represents the matrix element at it’s matrix position/index.
• i‘ represents the row index
• j‘ represents the column index
• Means A00=Aij  where i=0 and j=0A01=aij where i=0 and j=1 and like this.
• Here we have started row value from 0 and column value from 0.

Let’s see different ways to check sum of each row and each column of a matrix.

### Method-1: Java Program to Find the Sum of Each Row and Each Column of a Matrix By Static Initialization of Array Elements

Approach:

• Initialize and declare three arrays of, one with size 3×3 which is for matrix, rest empty with size 3 each which is for holding each row and each column sum.
• Use two for loops to iterate the rows and columns .
• Inside the for loops calculate the row and column sum together and store them in the blank arrays.
• Print the result using a for loop.

Program:

public class Matrix
{
public static void main(String args[])
{

// Initializing the 3X3 matrix i.e. 2D array
int arr[][] = {{19,25,32},{40,54,62},{70,20,60}};
int rowSum[] = new int[3],colSum[] = new int[3];
int row, col ;

System.out.print("The matrix elements are : ");
printMatrix(arr);

// Loops to calculate the row and column sums
for(row=0;row<3;row++)
{
for(col=0;col<3;col++)
{
rowSum[row] += arr[row][col];
colSum[row] += arr[col][row];
}
}
// Loop to print the rows and column sums
for(row=0;row<3;row++)
{
System.out.print("\nSum of "+(row+1)+" row = "+rowSum[row]);
System.out.print("\nSum of "+(row+1)+" column = "+colSum[row]);
}
}

// Function to print the matrix
static void printMatrix(int arr[][])
{
int row, col;
// Loop to print the elements
for(row=0;row<3;row++)
{
// Used for formatting
System.out.print("\n");
for(col=0;col<3;col++)
{
System.out.print(arr[row][col]+" ");
}
}
}
}


Output:

The matrix elements are :
19 25 32
40 54 62
70 20 60
Sum of 1 row = 76
Sum of 1 column = 129
Sum of 2 row = 156
Sum of 2 column = 99
Sum of 3 row = 150
Sum of 3 column = 154

### Method-2: Java Program to Find the Sum of Each Row and Each Column of a Matrix By Dynamic Initialization of Array Elements

Approach:

• Declare three arrays of, one with size 3×3 which is for matrix, rest empty with size 3 each which is for holding each row and each column sum.
• Ask the user for input and store them in the one array using two for loops
• Use two for loops to iterate the rows and columns .
• Inside the for loops calculate the row and column sum together and store them in the blank arrays.
• Print the result using a for loop.

Program:

import java.util.Scanner;
public class matrix{
public static void main(String args[])
{
//Scanner class to take input
Scanner scan = new Scanner(System.in);

// Initializing the 3X3 matrix i.e. 2D array
int arr[][] = new int[3][3];
//Arrays declared toholfd row andcolumn sum
int rowSum[] = new int[3],colSum[] = new int[3];
int row, col ;

// Taking matrix1 input
System.out.println("\nEnter matrix elements : ");
for(row=0;row<3;row++)
for(col=0;col<3;col++)
arr[row][col] = scan.nextInt();

System.out.print("The matrix elements are : ");
printMatrix(arr);

// Loops to calculate the row and column sums
for(row=0;row<3;row++)
{
for(col=0;col<3;col++)
{
rowSum[row] += arr[row][col];
colSum[row] += arr[col][row];
}
}
// Loop to print the rows and column sums
for(row=0;row<3;row++)
{
System.out.print("\nSum of "+(row+1)+" row = "+rowSum[row]);
System.out.print("\nSum of "+(row+1)+" column = "+colSum[row]);
}
}

// Function to print the matrix
static void printMatrix(int arr[][])
{
int row, col;
// Loop to print the elements
for(row=0;row<3;row++)
{
// Used for formatting
System.out.print("\n");
for(col=0;col<3;col++)
{
System.out.print(arr[row][col]+" ");
}
}
System.out.print("\n");
}
}


Output:

Enter matrix elements :
The matrix elements are :
11 21 31
10 12 11
13 14 15

Sum of 1 row = 63
Sum of 1 column = 34
Sum of 2 row = 33
Sum of 2 column = 47
Sum of 3 row = 42
Sum of 3 column = 57

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