JAVA Help

import java.util.*;
class midpoint
{
    int x,y;
    midpoint()
    {
        x=0;
        y=0;
    }
    void get()
    {
        Scanner s=new Scanner(System.in);
        System.out.println("Enter the absicca and ordinate");
        x=s.nextInt();
        y=s.nextInt();
    }
    void calculate(midpoint A, midpoint B)
    {
        this.x=(A.x + B.x)/2;
        this.y=(A.y + B.y)/2;
    }
    void show()
    {
        System.out.println("x="+x);
        System.out.println("y="+y);
    }
    public static void main()
    {
        midpoint A = new midpoint();
        midpoint B = new midpoint();
        midpoint M = new midpoint();
        System.out.println("Point A");
        A.get();
        System.out.println("Point B");
        B.get();
        M.calculate(A,B);
        System.out.println("Mid Point co-ordinates");
        M.show();
    }
}
      

import java.util.*;
class addmatrix
{
    int dda[][];
    int row;
    int col;
    addmatrix(int v1, int v2)
    {
        row=v1;
        col=v2;
        dda=new int[row][col];
    }
    void input()
    {
        Scanner s=new Scanner(System.in);
        System.out.println("Enter the elements of the array");
        for (int i=0; i< row; i++)
        {
            for (int j=0; j< col; j++)
            {
                dda[i][j]=s.nextInt();
            }
        }
    }
    void add(addmatrix a, addmatrix b)
    {
        for (int i=0; i< row; i++)
        {
            for (int j=0; j< col; j++)
            {
                this.dda[i][j]=a.dda[i][j]+b.dda[i][j];
            }
        }
    }
    void display()
    {
        for (int i=0; i< row; i++)
        {
            for (int j=0; j< col; j++)
            {
                System.out.print(dda[i][j]+"\t");
            }
            System.out.println();
        }
    }
    public static void main()
    {
        Scanner s=new Scanner(System.in);
        System.out.println("Enter the rows and colums of the matrices");
        int r=s.nextInt();
        int c=s.nextInt();
        addmatrix a= new addmatrix(r,c);
        addmatrix b= new addmatrix(r,c);
        addmatrix m= new addmatrix(r,c);
        System.out.println("For Matrix A[][]");
        a.input();
        System.out.println("For Matrix B[][]");
        b.input();
        m.add(a,b);
        System.out.println("For Matrix A[][]");
        a.display();
        System.out.println("For Matrix B[][]");
        b.display();
        System.out.println("Resultant Matrix C[][]");
        m.display();
    }
}