This guide covers how to build and run the Currency Converter application from source code.
Prerequisites
You need Java Development Kit (JDK) 17 or higher installed on your system.
java -version
javac -version
Project Structure
The project follows a standard Java package structure:
source/
├── lib/
│ └── gson-2.10.1.jar # JSON parsing library
├── src/
│ └── lad/com/alura/conversormoneda/
│ ├── controladores/
│ │ └── ConversorApp.java # Main application entry point
│ ├── modelos/
│ │ ├── ConsultaMoneda.java # API communication service
│ │ └── RegistroConversion.java # Conversion history record
│ └── vista/
│ └── Conversor.java # User interface menu
Package Organization
- controladores: Application controller and main entry point
- modelos: Business logic and data models
- vista: User interface components
Building from Source
Navigate to project directory
Compile all Java source files with Gson in the classpath:
javac -cp "lib/gson-2.10.1.jar" -d out src/lad/com/alura/conversormoneda/**/*.java
-cp "lib/gson-2.10.1.jar" - Adds Gson library to classpath
-d out - Places compiled .class files in the out directory
src/lad/com/alura/conversormoneda/**/*.java - Compiles all Java files in the package
Check that the out directory was created with compiled classes:
ls -la out/lad/com/alura/conversormoneda/
Running the Application
After successful compilation, run the application:
java -cp "out:lib/gson-2.10.1.jar" lad.com.alura.conversormoneda.controladores.ConversorApp
On Windows, use semicolon (;) instead of colon (:) as the classpath separator:java -cp "out;lib/gson-2.10.1.jar" lad.com.alura.conversormoneda.controladores.ConversorApp
Output Directory Structure
After compilation, the out directory mirrors the package structure:
out/
└── lad/
└── com/
└── alura/
└── conversormoneda/
├── controladores/
│ └── ConversorApp.class
├── modelos/
│ ├── ConsultaMoneda.class
│ └── RegistroConversion.class
└── vista/
└── Conversor.class
Cleaning Build Files
To remove compiled classes and start fresh:
Troubleshooting
ClassNotFoundException
If you see ClassNotFoundException for Gson classes, ensure:
- The
lib/gson-2.10.1.jar file exists
- You included
-cp "lib/gson-2.10.1.jar" during compilation
- You included both
out and lib/gson-2.10.1.jar in the classpath when running
Package Does Not Exist
If compilation fails with “package does not exist” errors:
- Verify all source files are in the correct package directories
- Check that package declarations match the directory structure
Wrong Java Version
The application uses modern Java features (records, text blocks, switch expressions). Ensure you’re using JDK 17+.