Skip to main content

​
Prerequisites

Before installing the Currency Converter, ensure you have the following:

Java JDK

Java Development Kit 11 or higher

Git

Git for cloning the repository
The application requires Java 11+ because it uses modern features like HttpClient, var, switch expressions with yield, and records.

​
Verify Java Installation

Check your Java version: 
java -version
javac -version
You should see output indicating Java 11 or higher. If not, download and install the latest JDK from Oracle or OpenJDK.

​
Installation Steps

1

Clone the Repository

Clone the Currency Converter repository to your local machine:
git clone https://github.com/yourusername/currency-converter.git
cd currency-converter
Replace yourusername with the actual GitHub username or organization where the repository is hosted.
2

Verify Project Structure

Ensure the project structure is correct:
ls -la
You should see:
├── lib/
│   └── gson-2.10.1.jar
├── src/
│   └── lad/com/alura/conversormoneda/
├── .gitignore
└── Conversor_de_Moneda_Challenge_ONE_Java_Backend.iml
3

Compile the Application

Compile the Java source files with the Gson dependency:
javac -cp "lib/gson-2.10.1.jar" -d out src/lad/com/alura/conversormoneda/**/*.java
This command:
  • -cp "lib/gson-2.10.1.jar" - Adds Gson library to the classpath
  • -d out - Outputs compiled .class files to the out directory
  • src/lad/com/alura/conversormoneda/**/*.java - Compiles all Java files in the package
If you’re on Windows, use semicolons instead of colons in the classpath: -cp "lib/gson-2.10.1.jar"
4

Verify Compilation

Check that the compilation was successful:
ls out/lad/com/alura/conversormoneda/
You should see the compiled directories:
controladores/
modelos/
vista/

​
Alternative: Using an IDE

You can also open the project in your favorite Java IDE:
  1. Open IntelliJ IDEA
  2. Select File > Open
  3. Navigate to the project directory and select it
  4. IntelliJ will automatically detect the .iml file
  5. Right-click on lib/gson-2.10.1.jar and select Add as Library
  6. Run the application from ConversorApp.java

​
Troubleshooting

This error means the Gson library is not in your classpath.Solution: Make sure to include -cp "lib/gson-2.10.1.jar" when compiling and running:
javac -cp "lib/gson-2.10.1.jar" -d out src/lad/com/alura/conversormoneda/**/*.java
java -cp "out:lib/gson-2.10.1.jar" lad.com.alura.conversormoneda.controladores.ConversorApp
Your Java version is too old.Solution: Upgrade to Java 11 or higher. The application uses modern Java features like:
  • java.net.http.HttpClient (Java 11+)
  • Records (Java 14+, used in RegistroConversion)
  • Switch expressions with yield (Java 13+)
The path to source files is incorrect.Solution: Make sure you’re in the project root directory and the src folder exists:
pwd  # Should show the project root
ls src/lad/com/alura/conversormoneda/  # Should list the package directories
The application includes an API key for ExchangeRate-API in the source code. For production use, you should:
  1. Register for your own API key at exchangerate-api.com
  2. Store the key in an environment variable
  3. Load it from configuration instead of hardcoding

​
Next Steps

Quick Start Guide

Learn how to run the application and perform your first currency conversion

Build docs developers (and LLMs) love

Get started for freeTalk to us