Simple Weather CLI Application

A command-line application written in Java that fetches the current weather information for a specified city using the OpenWeatherMap API.

Features

• Fetches current weather conditions (temperature, description).
• Accepts city name as a command-line argument.
• Displays weather information directly in the console.
• Uses Maven for dependency management and building.

Prerequisites

Before you begin, ensure you have the following installed on your system (macOS instructions provided based on prior discussion):

1. Java Development Kit (JDK): Version 11 or later is required.
   • Verify installation: java -version
   • Install using Homebrew (recommended): brew install openjdk@17 (or brew install openjdk for latest)
   • Ensure JAVA_HOME is set correctly if installed manually.
2. Apache Maven: Used for building the project and managing dependencies.
   • Verify installation: mvn -version
   • Install using Homebrew (recommended): brew install maven

Setup

1. Clone the Repository:

   git clone <your-repository-url>
   cd <repository-directory>

2. Get an OpenWeatherMap API Key:

   • Sign up for a free API key at OpenWeatherMap Free Tier.

3. Configure API Key:

   • This application requires the OpenWeatherMap API key to function. Do not hardcode your API key in the source code.
   • The recommended way is to set an environment variable named OPENWEATHERMAP_API_KEY.
   • In your terminal session (or add to your ~/.zshrc or ~/.bash_profile for persistence):

     export OPENWEATHERMAP_API_KEY="<Your_API_Key>"

   • Replace <Your_API_Key> with the actual key you obtained. The application code will read this environment variable.

Building the Project

Maven is used to compile the source code, run tests, and package the application into an executable JAR file.

1. Compile and Package:
   • Navigate to the project's root directory (where pom.xml is located) in your terminal.
   • Run the following Maven command:

     mvn clean package

   • This command will:
     • Clean previous builds.
     • Compile the source code.
     • Run unit tests (via Surefire plugin).
     • Package the application into an executable JAR file with all dependencies included (using the Assembly plugin).
   • The resulting JAR file will be located in the target/ directory, typically named something like weather-app-1.0-SNAPSHOT-jar-with-dependencies.jar.

Running the Application

Once the project is built, you can run the application from the command line using the packaged JAR file.

1. Execute the JAR:

   • Make sure you are in the project's root directory.

   • Run the application using java -jar, providing the city name as an argument:

     java -jar target/weather-app-1.0-SNAPSHOT-jar-with-dependencies.jar "<CityName>"

   • Replace <CityName> with the desired city (use quotes if the city name contains spaces, e.g., "New York").

   • Example:

     java -jar target/weather-app-1.0-SNAPSHOT-jar-with-dependencies.jar "London"

   • The application will output the current weather information for the specified city or an error message if something goes wrong.

Running Tests

The project includes unit and integration tests.

1. Run Unit Tests Only:

   • This executes tests that do not require network access or external dependencies (using mocks).
   • Command:

     mvn test

2. Run Unit and Integration Tests:

   • This executes both unit tests and integration tests (which might hit the actual OpenWeatherMap API).
   • Requires: The OPENWEATHERMAP_API_KEY environment variable must be set correctly for integration tests to pass.
   • Command (uses the Failsafe plugin, typically bound to the verify phase):

     mvn verify

Project Structure

The project follows standard Maven directory layout:

• src/main/java: Contains the main application source code.
  • com.weather.app: Contains all application classes:
    • WeatherApp.java: Main application class.
    • WeatherService.java: Service layer.
    • WeatherApiClient.java: API client interface.
    • OpenWeatherMapClient.java: OpenWeatherMap implementation of the API client.
    • WeatherData.java: Data model.
    • WeatherApiException.java: Custom exception class.
    • ConfigUtil.java: Configuration utility for API key management.
• src/test/java: Contains the test source code (JUnit/Mockito tests).
  • test.java.com.weather.app: Contains all test classes.
• pom.xml: Maven project configuration file (dependencies, plugins, build settings).
• target/: Directory where compiled code and packaged JARs are placed by Maven.

Configuration

• API Key: The OpenWeatherMap API key is configured via the OPENWEATHERMAP_API_KEY environment variable (see Setup section).