Low-level design (LLD) for Google Maps:

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.
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.
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.
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.
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.
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.

Code

// Enum for different Map Layers
public enum MapLayer {
    TRAFFIC,
    SATELLITE,
    TERRAIN,
    TRANSIT,
    DEFAULT
}

// Interface for map layers management
public interface LayerManagement {
    void enableLayer(MapLayer layer);
    void disableLayer(MapLayer layer);
}

// Implementation of Layer Management
public class DefaultLayerManagement implements LayerManagement {
    private final Set<MapLayer> enabledLayers;

    public DefaultLayerManagement() {
        this.enabledLayers = new HashSet<>();
    }

    @Override
    public void enableLayer(MapLayer layer) {
        enabledLayers.add(layer);
    }

    @Override
    public void disableLayer(MapLayer layer) {
        enabledLayers.remove(layer);
    }

    public Set<MapLayer> getEnabledLayers() {
        return enabledLayers;
    }
}

// MapRenderer class to handle rendering logic and user interactions (panning/zooming)
public class MapRenderer {
    private final TileCachingService tileCachingService;
    private final LayerManagement layerManagement;

    public MapRenderer(TileCachingService tileCachingService, LayerManagement layerManagement) {
        this.tileCachingService = tileCachingService;
        this.layerManagement = layerManagement;
    }

    public void render(Location center, int zoomLevel) {
        List<MapTile> tiles = tileCachingService.getTiles(center, zoomLevel, layerManagement.getEnabledLayers());
        for (MapTile tile : tiles) {
            // Render each map tile on the UI
            displayTile(tile);
        }
    }

    public void zoomIn(Location center) {
        int newZoomLevel = Math.min(TileCachingService.MAX_ZOOM_LEVEL, tileCachingService.getZoomLevel() + 1);
        render(center, newZoomLevel);
    }

    public void zoomOut(Location center) {
        int newZoomLevel = Math.max(TileCachingService.MIN_ZOOM_LEVEL, tileCachingService.getZoomLevel() - 1);
        render(center, newZoomLevel);
    }

    public void pan(Location newCenter) {
        render(newCenter, tileCachingService.getZoomLevel());
    }

    private void displayTile(MapTile tile) {
        // Code to display the tile on the map canvas (e.g., via a UI library)
        System.out.println("Displaying tile at " + tile.getX() + ", " + tile.getY());
    }
}

// MapTile class representing a single tile on the map
public class MapTile {
    private final int x;
    private final int y;
    private final String imageUrl;
    private final MapLayer layer;

    public MapTile(int x, int y, String imageUrl, MapLayer layer) {
        this.x = x;
        this.y = y;
        this.imageUrl = imageUrl;
        this.layer = layer;
    }

    public int getX() {
        return x;
    }

    public int getY() {
        return y;
    }

    public String getImageUrl() {
        return imageUrl;
    }

    public MapLayer getLayer() {
        return layer;
    }
}

// Tile Caching Service for optimizing map rendering
public class TileCachingService {
    public static final int MAX_ZOOM_LEVEL = 20;
    public static final int MIN_ZOOM_LEVEL = 0;

    private final Map<String, MapTile> tileCache;
    private int zoomLevel;

    public TileCachingService() {
        this.tileCache = new HashMap<>();
        this.zoomLevel = 10; // Default zoom level
    }

    public List<MapTile> getTiles(Location center, int zoomLevel, Set<MapLayer> enabledLayers) {
        // Calculate visible tiles based on the center location and zoom level
        // Return cached tiles if available, otherwise fetch them from the server
        this.zoomLevel = zoomLevel;
        return fetchTilesFromServer(center, enabledLayers);
    }

    private List<MapTile> fetchTilesFromServer(Location center, Set<MapLayer> layers) {
        List<MapTile> tiles = new ArrayList<>();
        for (MapLayer layer : layers) {
            // Fetch and cache the tiles for each layer (e.g., from a server)
            String url = generateTileUrl(center, layer, zoomLevel);
            MapTile tile = new MapTile(center.hashCode(), layer.hashCode(), url, layer);
            tileCache.put(url, tile);
            tiles.add(tile);
        }
        return tiles;
    }

    public int getZoomLevel() {
        return zoomLevel;
    }

    private String generateTileUrl(Location location, MapLayer layer, int zoomLevel) {
        // Generate a URL to fetch the map tile from the server
        return "https://mapserver.com/tiles/" + layer.name().toLowerCase() + "/" + zoomLevel + "/" + location.getLatitude() + "/" + location.getLongitude() + ".png";
    }
}

// Service for interacting with the map and rendering logic
public class MapService {
    private final MapRenderer mapRenderer;
    private final LayerManagement layerManagement;

    public MapService(MapRenderer mapRenderer, LayerManagement layerManagement) {
        this.mapRenderer = mapRenderer;
        this.layerManagement = layerManagement;
    }

    public void enableLayer(MapLayer layer) {
        layerManagement.enableLayer(layer);
        mapRenderer.render(new Location(0, 0), 10); // Re-render map with new layer enabled
    }

    public void disableLayer(MapLayer layer) {
        layerManagement.disableLayer(layer);
        mapRenderer.render(new Location(0, 0), 10); // Re-render map with the layer disabled
    }

    public void zoomIn(Location center) {
        mapRenderer.zoomIn(center);
    }

    public void zoomOut(Location center) {
        mapRenderer.zoomOut(center);
    }

    public void panMap(Location newCenter) {
        mapRenderer.pan(newCenter);
    }
}

// Model for Location
public class Location {
    private final double latitude;
    private final double longitude;

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

    public double getLatitude() {
        return latitude;
    }

    public double getLongitude() {
        return longitude;
    }
}

// Base interface for Place creation
public interface PlaceFactory {
    Place createPlace(String name, String address, Location location, String phoneNumber, String website, List<String> categories, List<String> tags, double rating, int reviewCount);
}

// Concrete implementation of Place creation
public class DefaultPlaceFactory implements PlaceFactory {
    public Place createPlace(String name, String address, Location location, String phoneNumber, String website, List<String> categories, List<String> tags, double rating, int reviewCount) {
        return new Place(IdGenerator.generateId(), name, address, location, phoneNumber, website, categories, tags, rating, reviewCount);
    }
}

// Entity representing a Place
public class Place {
    private final long id;
    private final String name;
    private final String address;
    private final Location location;
    private final String phoneNumber;
    private final String website;
    private final List<String> categories;
    private final List<String> tags;
    private final double rating;
    private final int reviewCount;

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

    // Getters...
}

// Enum for different transportation modes, applying the Strategy Pattern
public enum TransportationMode {
    DRIVING(new DrivingModeStrategy()),
    WALKING(new WalkingModeStrategy()),
    CYCLING(new CyclingModeStrategy());

    private final RouteStrategy strategy;

    TransportationMode(RouteStrategy strategy) {
        this.strategy = strategy;
    }

    public RouteStrategy getStrategy() {
        return strategy;
    }
}

// Strategy Pattern for Route Calculation based on different modes
public interface RouteStrategy {
    double calculateDuration(Route route);
}

public class DrivingModeStrategy implements RouteStrategy {
    public double calculateDuration(Route route) {
        // Calculate duration for driving
        return route.getDistance() / 50.0; // Assuming average speed of 50 km/h
    }
}

public class WalkingModeStrategy implements RouteStrategy {
    public double calculateDuration(Route route) {
        // Calculate duration for walking
        return route.getDistance() / 5.0; // Assuming average walking speed of 5 km/h
    }
}

public class CyclingModeStrategy implements RouteStrategy {
    public double calculateDuration(Route route) {
        // Calculate duration for cycling
        return route.getDistance() / 15.0; // Assuming average cycling speed of 15 km/h
    }
}

// Service for calculating distances between locations
public class DistanceCalculatorService {
    private static final int EARTH_RADIUS_KM = 6371;

    public double calculateDistance(Location loc1, Location loc2) {
        double lat1 = Math.toRadians(loc1.getLatitude());
        double lon1 = Math.toRadians(loc1.getLongitude());
        double lat2 = Math.toRadians(loc2.getLatitude());
        double lon2 = Math.toRadians(loc2.getLongitude());

        double dLat = lat2 - lat1;
        double dLon = lon2 - lon1;

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

        return EARTH_RADIUS_KM * c;
    }
}

// Route class representing a specific path between locations
public class Route {
    private final long id;
    private final List<Location> waypoints;
    private final List<Place> places;
    private final double distance;
    private final TransportationMode mode;

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

    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 mode.getStrategy().calculateDuration(this);
    }

    public TransportationMode getMode() {
        return mode;
    }
}

// Service responsible for route planning
public class RoutePlannerService {
    private final DistanceCalculatorService distanceCalculator;
    private final CacheService cacheService;

    public RoutePlannerService(DistanceCalculatorService distanceCalculator, CacheService cacheService) {
        this.distanceCalculator = distanceCalculator;
        this.cacheService = cacheService;
    }

    public Route planRoute(Location start, Location end, List<Location> waypoints, TransportationMode mode) {
        // Check cache first for precomputed routes
        Route cachedRoute = cacheService.getCachedRoute(start, end, waypoints, mode);
        if (cachedRoute != null) {
            return cachedRoute;
        }

        // Otherwise, calculate a new route
        double distance = distanceCalculator.calculateDistance(start, end);
        Route route = new Route(waypoints, new ArrayList<>(), distance, mode);
        cacheService.cacheRoute(route);

        return route;
    }
}

// Service responsible for searching places and routes
public class SearchService {
    private final Map<Long, Place> places;
    private final Map<Long, Route> routes;

    public SearchService(Map<Long, Place> places, Map<Long, Route> routes) {
        this.places = places;
        this.routes = routes;
    }

    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 new DistanceCalculatorService().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;
    }
}

// Cache Service to store frequently used routes and distance calculations
public class CacheService {
    private final Map<String, Route> routeCache = new HashMap<>();

    public Route getCachedRoute(Location start, Location end, List<Location> waypoints, TransportationMode mode) {
        String key = generateCacheKey(start, end, waypoints, mode);
        return routeCache.get(key);
    }

    public void cacheRoute(Route route) {
        String key = generateCacheKey(route.getWaypoints().get(0), route.getWaypoints().get(route.getWaypoints().size() - 1), route.getWaypoints(), route.getMode());
        routeCache.put(key, route);
    }

    private String generateCacheKey(Location start, Location end, List<Location> waypoints, TransportationMode mode) {
        return start.getLatitude() + "," + start.getLongitude() + "->" + end.getLatitude() + "," + end.getLongitude() + ":" + mode.getMode();
    }
}

Design (LLD) Google Maps - Machine Coding

Table of contents