Weather Forecast App Assignment

Task

Create an Android app that displays the weather forecast.

Requirements

1. Display the weather forecast for the current day.
2. Display the weather forecast for the week.
3. Display the weather forecast for the current city.
4. Allow the user to choose any other city and view its weather forecast.
5. The solution must contain at least one feature module.

Implementation

The developed app is called F☀️recast. The following sections detail its features, design decisions, tech stack, architecture, and development tools used.

Screenshots

Features

• Display the current weather forecast for the user's location (Requirements: 1, 2)
• Search for cities and display their current weather forecast (Requirements: 3, 4)
• Select a city or location and view the weekly weather forecast (Requirement 2)
• Switch between Celsius and Fahrenheit temperature units

Design

• Material 3 design system
• "Warm Coastal" app theme
• Light mode ("midday sun on warm sand") and dark mode ("beach fire at night")
• Temperature-reactive color scheme — the UI adapts its colors to reflect the current temperature

Tech Stack

Category	Library
Language	Kotlin
UI	Jetpack Compose, Material 3
Navigation	Jetpack Navigation Compose
Dependency Injection	Hilt
Concurrency	Coroutines, Flow
Networking	Ktor
Serialization	Kotlin Serialization
Lifecycle	AndroidX Lifecycle, ViewModel
Collections	KotlinX Immutable Collections
Logging	Timber
Testing	JUnit
Weather Data	Open Meteo — open source, free for non-commercial use, no API key required
Geocoding	Nominatim — open source, free for non-commercial use, no API key required

Architecture

The app follows Clean Architecture principles, with modules organized into three horizontal layers — presentation, domain, and data. The domain layer sits between presentation and data, and dependencies always point inward toward the domain.

Module	Description
:app	Entry point — assembles modules and wires navigation
:common	Shared utilities across all layers
:domain	Highest level module — contains business logic and use cases, no dependencies on other modules
:domain:dataapi	Contracts (interfaces) between the data layer and domain layer
:domain:presentationapi	Contracts (interfaces) between the domain layer and presentation layer
:data:weather	Data layer — retrieves weather forecasts for coordinates
:data:geocoding	Data layer — retrieves geographic coordinates from search strings
:data:location	Data layer — retrieves the device's geographic coordinates
:data:common	Shared data layer utilities
:ui:common	Shared UI theme and components across the presentation layer
:feature:cityforecast	Feature module in the presentation layer — city list and detail screens (Requirement 5)

CityForecast Feature Module

This feature module delivers the features listed above — displaying weather forecasts for cities, using an MVVM architecture with unidirectional data flow.

The public interface is intentionally minimal. The feature registers its screens via a NavGraphBuilder extension:

fun NavGraphBuilder.cityForecastNavGraph(appContainerState: AppContainerState)

Call this within a NavHost block (in AppContainerNavHost in :app) to add the city list and detail screens to the navigation graph.

Tools & Assistance

• Project was bootstrapped from my existing repo RickAndMortyInterviewCoding and developed from there
• Material Theme Builder — inspiration for the app's color scheme
• Image Asset Studio (built into Android Studio) — generated the launch icon from a source image
• Claude — used as a development assistant throughout the project:
  • Recommended the free APIs used for weather data and geocoding
  • Jetpack Compose patterns and best practices
  • Architecture decisions and code review
  • Generating unit tests
  • App icon image generation
  • Theme design and color system
  • The :data:location module and location permission UI were fully generated by Claude Code — boilerplate I had no interest in writing by hand. The only manual change was converting the location service from a suspend function to a Flow.

Note

All code was reviewed, understood, and integrated by the author.