Java Program to Count the Numbers of 1’s in a Binary Matrix

In the previous article, we have discussed Java Program to Find the Product Between Sums of Two Diagonals of a Matrix

In this article we are going to see how we can write a program to count number of one’s in a binary matrix in JAVA language. A binary matrix is a matrix that has only 0 or 1 as its elements.

Java Program to Count the Numbers of 1’s in a Binary 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.

A binary matrix is a matrix that has only 0 or 1 as its elements.

Let’s see different ways to count the Numbers of 1’s in a Binary Matrix.

Method-1: Java Program to Count the Numbers of 1’s in a Binary Matrix By Static Initialization of Array Elements

Approach:

  • Initialize and an array of size 3×3, with elements.
  • Use two for loops to iterate the rows and columns .
  • Inside the for loops count all ones’ using a counter.
  • Print the result.

Program:

public class matrix
{
    public static void main(String args[])
    {
        // Initializing the 3X3 matrix i.e. 2D array
        int arr[][] = {{1,0,0},{0,1,0},{1,1,1}};
        int row, col, count = 0;

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

        // Loops to total number of one's in a binary matrix
        for(row=0;row<3;row++)
            for(col=0;col<3;col++)
            {
                if(arr[row][col]==1)
                    count++;
            }   
        
        System.out.println("\nNumber of ones' in the binary matrix are : "+count);
    }

    // Method 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:

The matrix elements are : 
1 0 0 
0 1 0 
1 1 1

Number of ones' in the binary matrix are : 5

Method-2: Java Program to Count the Numbers of 1’s in a Binary Matrix By Dynamic Initialization of Array Elements

Approach:

  • Declare one array of size 3×3.
  • Ask the user for input of array elements and store them in the array using two for loops.
  • Use two for loops to iterate the rows and columns .
  • Inside the for loops count all ones’ using a counter.
  • Print the result.

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];
        int row, col ,count = 0;

        // Taking matrix1 input
        System.out.println("Enter 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 total number of ones' in a binary matrix
        for(row=0;row<3;row++)
            for(col=0;col<3;col++)
            {
                if(arr[row][col]==1)
                    count++;
            }   
        
        System.out.println("\nNumber of ones' in the binary matrix are : "+count);
    }

    // Method 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 : 1 1 1 1 1 1 1 0 0
The matrix elements are:
1 1 1 
1 1 1 
1 0 0

Number of ones' in the binary matrix are : 7

Want to excel in java coding? Practice with these Java Programs examples with output and write any kind of easy or difficult programs in the java language.

Related Java Programs: