Mobile Weather App Class Diagram

This class diagram outlines the structure of a mobile weather app, integrating weather data management, user interface (UI) components, and system interactions to deliver real-time weather information.

Core Classes & Attributes

1. WeatherData
   • Attributes: Timestamp, Temperature, Humidity, WindSpeed, PrecipitationProbability, SkyCondition (e.g., "Sunny", "Rainy"), Location (City, Country).
   • Methods: fetchDataFromAPI(), updateForecast().
   • Role: Represents raw weather information retrieved from external APIs (e.g., OpenWeatherMap, AccuWeather).
2. Forecast
   • Attributes: ForecastID, DayOfWeek, MinTemperature, MaxTemperature.
   • Associations:
     • One-to-Many with WeatherData: Aggregates hourly WeatherData into daily forecasts (e.g., 24-hour data for "Day 1").
3. LocationManager
   • Methods: getCurrentLocation(), saveFavoriteLocation(String), loadFavoriteLocations().
   • Role: Manages user locations (current GPS or saved favorites), integrating with device APIs for geolocation.
4. UIComponent
   • Subclasses:
     • HomeScreen: Displays current weather, hourly forecast, and favorite locations.
     • DetailedForecastScreen: Shows extended 7-day forecast with Forecast data.
     • SettingsScreen: Allows theme customization (e.g., Dark Mode) and unit preferences (Celsius/Fahrenheit).
   • Common Attributes: Theme (Light/Dark), Units (TemperatureUnit, SpeedUnit).
   • Methods: renderWeather(WeatherData), updateUIOnRefresh().
5. WeatherService
   • Methods: fetchCurrentWeather(Location), fetchExtendedForecast(Location).
   • Role: Acts as an abstract interface for weather data providers, implemented by concrete classes like OpenWeatherAPIService.
6. NotificationManager
   • Methods: sendAlert(String message), scheduleDailyForecastNotification().
   • Role: Triggers weather alerts (e.g., severe storm warnings) and daily forecast updates.

Key Relationships

1. WeatherService ↔ WeatherData: Dependency
   • WeatherService retrieves data and populates WeatherData objects (e.g., OpenWeatherAPIService returns JSON parsed into WeatherData).
2. LocationManager ↔ UIComponent: Association
   • HomeScreen uses LocationManager to display current or favorite locations (e.g., "Fetching location for UI...").
3. Forecast ↔ WeatherData: Composition
   • A Forecast day consists of multiple WeatherData entries (e.g., hourly data points for temperature throughout the day).
4. UIComponent ↔ NotificationManager: Dependency
   • SettingsScreen allows users to configure notifications, triggering NotificationManager methods.

Data Flow & Workflow

1. Data Retrieval:
   • LocationManager gets the user’s current location or a saved favorite.
   • WeatherService (e.g., OpenWeatherAPIService) calls external APIs to fetch WeatherData and Forecast for the location.
2. UI Rendering:
   • HomeScreen uses WeatherData to display current conditions (temperature, sky icon) and Forecast for hourly previews.
   • DetailedForecastScreen iterates through Forecast objects to show 7-day trends, leveraging WeatherData for each day’s details.
3. User Interaction:
   • Users switch between UIComponent screens (e.g., tapping "Settings" to change units), updating preferences stored in UIComponent.
   • Pull-to-refresh triggers WeatherService.fetchCurrentWeather() to reload WeatherData and update the UI.
4. Notifications:
   • NotificationManager sends alerts based on WeatherData (e.g., high precipitation probability) or user-scheduled daily updates.

Design Principles

• Separation of Concerns:
  • WeatherService handles data fetching, LocationManager manages geolocation, and UIComponent focuses on display logic.
• Abstraction:
  • The WeatherService interface allows swapping API providers (e.g., from OpenWeatherMap to a custom backend) without altering UI classes.
• Reusability:
  • WeatherData and Forecast classes are shared across HomeScreen and DetailedForecastScreen, reducing code duplication.