The solution for the Mars Rover problem

Constants.java

package com.app.eyepax;

public class Constants {

    public static final Integer N = 1;
    public static final Integer E = 2;
    public static final Integer S = 3;
    public static final Integer W = 4;

}

MarsRoverProblem.java

package com.app.eyepax;

import java.util.Objects;

public class MarsRoverProblem {

    Integer x = 0;
    Integer y = 0;
    Integer front = 1;

    public void setRoverPosition(Integer x, Integer y, Integer front) {
        this.x = x;
        this.y = y;
        this.front = front;
    }

    //    print the rover position
    public void printRoverPosition() {
     
        char direction = 'N';

        switch (front) {
            case 1:
                direction = 'N';
                break;
            case 2:
                direction = 'E';
                break;
            case 3:
                direction = 'S';
                break;
            case 4:
                direction = 'W';
                break;
            default:
                break;
        }
        System.out.println(x + " " + y + " " + direction);
    }

    //    turn the rover left
    private void turnRoverLeft() {
        if (front - 1 < Constants.N)
            front = Constants.W;
        else
            front = front - 1;
    }

    //    turn the rover right
    private void turnRoverRight() {
        if (front + 1 > Constants.W)
            front = Constants.N;
        else
            front = front + 1;
    }

    //    move the rover
    private void move() {
        if (Objects.equals(front, Constants.N)) {
            this.y++;
        } else if (Objects.equals(front, Constants.E)) {
            this.x++;
        } else if (Objects.equals(front, Constants.S)) {
            this.y--;
        } else if (Objects.equals(front, Constants.W)) {
            this.x--;
        }
    }

    public void process(String input) {
        if (input != null) {
            for (int i = 0; i < input.length(); i++) {
                process(input.charAt(i));
            }
        }
    }

    //    process the rover position
    private void process(Character command) {
        if (command.equals('L')) {
            turnRoverLeft();
        } else if (command.equals('R')) {
            turnRoverRight();
        } else if (command.equals('M')) {
            move();
        } else {
            System.err.println("Error occurred");
        }
    }

    public static void main(String args[]) {
        MarsRoverProblem roverProblem = new MarsRoverProblem();

        roverProblem.setRoverPosition(1, 2, Constants.N);
        roverProblem.process("LMLMLMLMM");
        roverProblem.printRoverPosition();

        roverProblem.setRoverPosition(3, 3, Constants.E);
        roverProblem.process("MMRMMRMRRM");
        roverProblem.printRoverPosition();
    }
}