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Low Level Design (LLD) Coding

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Design (LLD) Google Maps - Machine Coding

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techlinks.in
·Dec 31, 2022·

5 min read

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Table of contents

  • Classes/Objects

Low-level design (LLD) for Google Maps:

  1. Geospatial data: Google Maps will need to store and manage large amounts of geospatial data, including information about roads, landmarks, and businesses. This will likely involve creating a database or data structure to store this information, as well as algorithms to process and index the data.

  2. Map rendering: Google Maps will need to render the map and display it to the user. This will involve implementing algorithms to project the geospatial data onto a 2D map and generate the necessary graphics and styling to display the map.

  3. Location services: Google Maps will need to determine the user's location and provide directions and other location-based services. This will involve integrating with location APIs and implementing algorithms to determine the user's location and generate directions.

  4. Search and discovery: Google Maps will need to allow users to search for places and businesses, and provide recommendations and reviews for nearby points of interest. This will involve implementing search algorithms and integrating with third-party APIs to provide the necessary data.

  5. User accounts and authentication: Google Maps will need to allow users to create accounts, log in, and log out. We will also need to implement measures to ensure the security of user accounts, such as password hashing and potentially two-factor authentication.

  6. User interface: Finally, Google Maps will need to design the user interface for the service, including the layout, navigation, and any necessary graphics or styling. This will involve creating wireframes and mockups, as well as implementing the front-end code to bring the design to life.

Classes/Objects

  1. Location: This class represents a geographic location on a map, typically defined by latitude and longitude coordinates.

  2. Place: This class represents a physical location on a map, such as a business, landmark, or other point of interest. It includes information such as the place's name, address, location, categories, and tags.

  3. Route: This class represents a path between two locations on a map, including information such as the start and end locations, mode of transportation, waypoints, and estimated travel time and distance.

  4. TransportationMode: This class represents the mode of transportation that can be used to travel a route, such as driving, walking, or taking public transportation.

  5. DistanceCalculator: This class includes utility methods for calculating the distance between two locations on a map.

  6. MapService: This is the main class that provides the interface for searching and manipulating routes and places on the map. It includes methods such as searchRoutes, searchPlaces, addRoute, getRoute, and others.

Here is a possible low-level design for a Google Maps-like service in Java:

public class Location {
    private double latitude;
    private double longitude;

    public Location(double latitude, double longitude) {
        this.latitude = latitude;
        this.longitude = longitude;
    }

    public double getLatitude() {
        return latitude;
    }

    public double getLongitude() {
        return longitude;
    }
}
public class Place {
    private long id;
    private String name;
    private String address;
    private Location location;
    private String phoneNumber;
    private String website;
    private List<String> categories;
    private List<String> tags;
    private double rating;
    private int reviewCount;

    public Place(String name, String address, Location location, String phoneNumber, String website, List<String> categories, List<String> tags, double rating, int reviewCount) {
        this.id = IdGenerator.generateId();
        this.name = name;
        this.address = address;
        this.location = location;
        this.phoneNumber = phoneNumber;
        this.website = website;
        this.categories = categories;
        this.tags = tags;
        this.rating = rating;
        this.reviewCount = reviewCount;
    }

    public long getId() {
        return id;
    }

    public String getName() {
        return name;
    }

    public String getAddress() {
        return address;
    }

    public Location getLocation() {
        return location;
    }

    public String getPhoneNumber() {
        return phoneNumber;
    }

    public String getWebsite() {
        return website;
    }

    public List<String> getCategories() {
        return categories;
    }

    public List<String> getTags() {
        return tags;
    }

    public double getRating() {
        return rating;
    }

    public int getReviewCount() {
        return reviewCount;
    }
}
public class Route {
    private long id;
    private List<Location> waypoints;
    private List<Place> places;
    private double distance;
    private double duration;

    public Route(List<Location> waypoints, List<Place> places, double distance, double duration) {
        this.id = IdGenerator.generateId();
        this.waypoints = waypoints;
        this.places = places;
        this.distance = distance;
        this.duration = duration;
    }

    public long getId() {
        return id;
    }

    public List<Location> getWaypoints() {
        return waypoints;
    }

    public List<Place> getPlaces() {
        return places;
    }

    public double getDistance() {
        return distance;
    }

    public double getDuration() {
        return duration;
    }
}
public class MapService {
    private Map<Long, Place> places;
    private Map<Long, Route> routes;

    public MapService() {
        this.places = new HashMap<>();
        this.routes = new HashMap<>();
    }

    public void addPlace(Place place) {
        places.put(place.getId(), place);
    }

    public Place getPlace(long id) {
        return places.get(id);
    }

    public List<Place> searchPlaces(String query, Location location, int radius, List<String> categories, List<String> tags) {
        List<Place> results = new ArrayList<>();
        for (Place place : places.values()) {
            if (placeMatchesQuery(place, query) && placeIsWithinRadius(place, location, radius) && placeHasMatchingCategories(place, categories) && placeHasMatchingTags(place, tags)) {
                results.add(place);
            }
        }
        return results;
    }

    private boolean placeMatchesQuery(Place place, String query) {
        return place.getName().toLowerCase().contains(query.toLowerCase()) || place.getAddress().toLowerCase().contains(query.toLowerCase());
    }

    private boolean placeIsWithinRadius(Place place, Location location, int radius) {
        return DistanceCalculator.calculateDistance(place.getLocation(), location) <= radius;
    }

    private boolean placeHasMatchingCategories(Place place, List<String> categories) {
        if (categories == null || categories.isEmpty()) {
            return true;
        }
        for (String category : categories) {
            if (place.getCategories().contains(category)) {
                return true;
            }
        }
        return false;
    }

    private boolean placeHasMatchingTags(Place place, List<String> tags) {
        if (tags == null || tags.isEmpty()) {
            return true;
        }
        for (String tag : tags) {
            if (place.getTags().contains(tag)) {
                return true;
            }
        }
        return false;
    }

    public void addRoute(Route route) {
        routes.put(route.getId(), route);
    }

    public Route getRoute(long id) {
        return routes.get(id);
    }

    public List<Route> searchRoutes(Location start, Location end, List<Location> waypoints, TransportationMode mode) {
        List<Route> results = new ArrayList<>();
        for (Route route : routes.values()) {
            if (route.getStart().equals(start) && route.getEnd().equals(end) && routeContainsWaypoints(route, waypoints) && route.getMode().equals(mode)) {
                results.add(route);
            }
        }
        return results;
    }

    private boolean routeContainsWaypoints(Route route, List<Location>                     waypoints) {
            if (waypoints == null || waypoints.isEmpty()) {
                return true;
            }
            for (Location waypoint : waypoints) {
                if (!route.getWaypoints().contains(waypoint)) {
                    return false;
                }
            }
            return true;
    }
}
public class TransportationMode {
  private String mode;

  public TransportationMode(String mode) {
    this.mode = mode;
  }

  public String getMode() {
    return mode;
  }
}
public class DistanceCalculator {
  private static final int EARTH_RADIUS_IN_KILOMETERS = 6371;

  public static double calculateDistance(Location location1, Location location2) {
    double lat1 = Math.toRadians(location1.getLatitude());
    double lon1 = Math.toRadians(location1.getLongitude());
    double lat2 = Math.toRadians(location2.getLatitude());
    double lon2 = Math.toRadians(location2.getLongitude());

    double deltaLat = lat2 - lat1;
    double deltaLon = lon2 - lon1;

    double a = Math.pow(Math.sin(deltaLat / 2), 2) +
               Math.cos(lat1) * Math.cos(lat2) *
               Math.pow(Math.sin(deltaLon / 2), 2);
    double c = 2 * Math.atan2(Math.sqrt(a), Math.sqrt(1 - a));

    return EARTH_RADIUS_IN_KILOMETERS * c;
  }
}

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