# Java Program to Print Boundary Elements of a Matrix

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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