Matrix addition 3X3 in java

//Matrix in java
import java.util.Scanner;
class Matrix_Ex
{
    Scanner sc=new Scanner(System.in);
    int i,j;
    int a[][]=new int[3][3];
    int b[][]=new int[3][3];
    int c[][]=new int[3][3];
    void get_matrix_a()
    {
        for(i=0;i<3;i++)
        {
            for(j=0;j<3;j++)
            {
                a[i][j]=sc.nextInt();
            }
        }
    }

    void get_matrix_b()
    {
        for(i=0;i<3;i++)
        {
            for(j=0;j<3;j++)
            {
                b[i][j]=sc.nextInt();
            }
        }
    }

    void print_a()
    {
        for(i=0;i<3;i++)
        {
            for(j=0;j<3;j++)
            {
                System.out.print(a[i][j]+" ");
            }
            System.out.println(" ");
        }
    }

    void print_b()
    {
        for(i=0;i<3;i++)
        {
            for(j=0;j<3;j++)
            {
                System.out.print(b[i][j]+" ");
            }
            System.out.println(" ");
        }
    }

    void sum_matrix()
    {
        for(i=0;i<3;i++)
        {
            for(j=0;j<3;j++)
            {
                c[i][j]=a[i][j]+b[i][j];
            }
        }
    }

    void print_c()
    {
        for(i=0;i<3;i++)
        {
            for(j=0;j<3;j++)
            {
                System.out.print(c[i][j]+" ");
            }
            System.out.println(" ");
        }
    }
}
class Arr_ex2
{
    public static void main(String args[])
    {
        Matrix_Ex o1=new Matrix_Ex();
        System.out.println("==>Enter 1st Matrix<==");
        o1.get_matrix_a();
        System.out.println("==>Enter 2nd Matrix<==");
        o1.get_matrix_b();
        System.out.println("==>Print 1st Matrix<==");
        o1.print_a();
        System.out.println("==>Enter 2nd Matrix<==");
        o1.print_b();
        o1.sum_matrix();
        System.out.println("==>Sum of matrix is <==");
        o1.print_c();
    }
}