Java Program to Print Boundary Elements of a Matrix

Java Program to Print Boundary Elements of a Matrix

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In the previous article, we have discussed Java Program to Print Boundary Elements of a Matrix

In this article we are going to see how we can print boundary elements in JAVA language.

Java Program to Print Boundary Elements 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 print boundary elements of a matrix.

Method-1: Java Program to Print Boundary Elements of a Matrix By Static Initialization of Array Elements

Approach:

  • Initialize and declare two one array of size 3×3 with elements.
  • Use two for loops to iterate the rows and columns .
  • Print the elements that are present in the first and last row and column. Rest print spaces.

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 row, col;

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

        System.out.print("\nThe boundary elements are : ");
        
        //Printing the boundary elements of a matrix
        for(row=0;row<3;row++)
        {
                // Used for formatting
            System.out.print("\n");
            for(col=0;col<3;col++)
                if(row==0||col==0||row==2||col==2)
                    System.out.print(arr[row][col]+" ");
                else
                    System.out.print("   ");
        }
    }

    // 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 : 
19 25 32 
40 54 62 
70 20 60

The boundary elements are : 
19 25 32 
40      62 
70 20 60

Method-2: Java Program to Print Boundary Elements of a 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 one array using two for loops.
  • Use two for loops to iterate the rows and columns .
  • Print the elements that are present in the first and last row and column. Rest print spaces.

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], temp[] = new int[3];
        int row, col;
        
        // Taking matrix 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);

        System.out.println("\n\nThe boundary elements are-");
        //Printing the boundary elements of a matrix
        for(row=0;row<3;row++)
        {
                // Used for formatting
            System.out.print("\n");
            for(col=0;col<3;col++)
                if(row==0||col==0||row==2||col==2)
                    System.out.print(arr[row][col]+" ");
                else
                    System.out.print("  ");
        }
    }

    // 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]+" ");
            }
        }
    }

}


Output:

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

The boundary elements are-

1 0 1 
1    1 
1 0 1

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