Multiply two n*n matrices

matrix.java

/*
 * Multiplies two n*n matrices.
 *
 * @author Gaurav Narula
 * */
import java.util.Scanner;

public class matrix {
    private int[][] arr;
    private int n;

    public matrix(int n){
        this.n = n;
        arr = new int[n][n];
    }

    public void multiply(matrix ob) {
        if(ob.n != this.n) {
            System.out.println("Matrices should be of same order");
            return;
        }

        int[][] product = new int[n][n];

        for(int i = 0; i < n; i++) {
            for(int j = 0; j < n; j++) {
                int sum = 0;
                for(int k = 0; k < n; k++) {
                    sum = sum + arr[i][k] * ob.arr[k][j];
                }
                product[i][j] = sum;
            }
        }

        display(product);
    }

    public void display(int[][] x) {
        for(int i = 0; i < n; i++) {
            for(int j = 0; j < n; j++) {
                System.out.print(x[i][j] + " ");
            }
            System.out.println();
        }
    }

    Scanner scan = new Scanner(System.in);

    public void input() {
        for(int i = 0; i < n; i++) {
            for(int j = 0; j < n; j++) {
                System.out.println("Enter value for row " + i + " column " + j);
                arr[i][j] = scan.nextInt();
            }
        }
    }

    public static void main(String[] args) {
        matrix ob = new matrix(3);
        ob.input();

        matrix ob2 = new matrix(3);
        ob2.input();

        ob.multiply(ob2);
    }
}