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

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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=0,  A01=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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