Java Program to Create a Matrix and Fill it with Prime Numbers

Prime Numbers are the number which can be divisible by only 1 and itself, it cannot be divisible by any other number. The task here is to find the prime numbers and store them in the form of a matrix.

Example:  

Prime numbers are: 2, 3, 5, 7

Output:
2    3
5    7

Prime numbers : 2, 3, 5, 7, 9, 11, 13, 17, 19

Output:
2    3     5
7    9     11
13    17    19

Approach: 

• First, the class should be created and inside the class a method is created to check the prime number.
• This method will take the number as input and then check whether it is prime or not. If it is prime then it will return true and if not then return false.
• Now, the main method will be created, inside the main method the object of Matrix class is made so that the isPrime() method can be accessed from the main.
• The number of rows and number of columns will be taken from the user and then using this, the another array will be created which is of size rows * columns.
• The prime numbers will be stored in this array.
• Now, by iterating through result[] array, the prime numbers will gets stored into the Matrix[] array. After that the result will gets printed.

Java

// Java Program to Create a Matrix and Fill
// it with Prime Numbers

import java.util.Scanner;

public class MatrixWithPrimeNumbers {
    // Function to check a number is prime or not
    boolean isPrime(int num)
    {
        int counter = 0;
        for (int i = 1; i <= num; i++)
        {
            if (num % i == 0)
                counter = counter + 1;
        }

        if (counter == 2)
            return true;
        else
            return false;
    }

    public static void main(String args[])
    {
        // creating object of Matrix With Prime Numbers
        // class
        MatrixWithPrimeNumbers mwp
            = new MatrixWithPrimeNumbers();

        // Enter the number of rows and column.
        int row = 4;
        int col = 4;

        // 2D array for storing prime numbers
        int Matrix[][] = new int[row][col];

        // size of resultant matrix
        int res = row * col;

        // 1D array for storing prime numbers
        int Result[] = new int[res];

        int i = 0, j;
        int k = 1;

        // Calling the method to check prime and
        // then result will be stored into the array
        while (i < res)
        {
            if (mwp.isPrime(k) == true)
            {
                Result[i] = k;
                i++;
            }
            k++;
        }

        // the result is now stored into the form
        // of matrix (in 2D array)
        int x = 0;
        for (i = 0; i < row; i++)
        {
            for (j = 0; j < col; j++)
            {
                Matrix[i][j] = Result[x];
                x++;
            }
        }

        // printing the result in 2D Array.
        System.out.println("The Resultant Matrix is : ");

        for (i = 0; i < row; i++)
        {
            for (j = 0; j < col; j++)
            {
                System.out.print(Matrix[i][j] + " ");
            }
            System.out.println();
        }
    }
}

Output

The Resultant Matrix is : 
2 3 5 7 
11 13 17 19 
23 29 31 37 
41 43 47 53