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The Currency Converter has minimal dependencies and uses manual compilation without build tools like Maven or Gradle.

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External Dependencies

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Gson 2.10.1

Location: lib/gson-2.10.1.jar Purpose: JSON parsing and serialization for API responses Usage: The ConsultaMoneda class uses Gson to parse JSON responses from the ExchangeRate-API: 
import com.google.gson.JsonElement;
import com.google.gson.JsonObject;
import com.google.gson.JsonParser;

// Parsing API response
JsonElement elemento = JsonParser.parseString(respuesta.body());
JsonObject objectRoot = elemento.getAsJsonObject();
return objectRoot.get("conversion_result").getAsDouble();
Why Gson?
  • Lightweight and reliable
  • Simple API for parsing JSON
  • No additional dependencies
  • Widely used in Java projects

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Java Standard Library

The application relies on several Java standard library packages:

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HTTP Client (java.net.http)

Introduced: Java 11 Usage: Making HTTP requests to the ExchangeRate-API 
import java.net.URI;
import java.net.http.HttpClient;
import java.net.http.HttpRequest;
import java.net.http.HttpResponse;

HttpClient cliente = HttpClient.newHttpClient();
HttpRequest request = HttpRequest.newBuilder()
    .uri(URI.create(url))
    .GET()
    .build();
Referenced in: src/lad/com/alura/conversormoneda/modelos/ConsultaMoneda.java:6-9

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Scanner (java.util)

Usage: Reading user input from console 
import java.util.Scanner;

Scanner sc = new Scanner(System.in);
int opcion = sc.nextInt();
double cantidad = sc.nextDouble();
Referenced in: src/lad/com/alura/conversormoneda/controladores/ConversorApp.java:10

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LocalDateTime (java.time)

Usage: Timestamping conversion history records 
import java.time.LocalDateTime;
import java.time.format.DateTimeFormatter;

RegistroConversion registro = new RegistroConversion(
    base, objetivo, cantidad, resultado, LocalDateTime.now()
);
Referenced in: src/lad/com/alura/conversormoneda/controladores/ConversorApp.java:7

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Collections (java.util)

Usage: Managing conversion history 
import java.util.ArrayList;
import java.util.List;

List<RegistroConversion> historial = new ArrayList<>();
Referenced in: src/lad/com/alura/conversormoneda/controladores/ConversorApp.java:8-9

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No Build Tool Required

This project intentionally does not use Maven or Gradle. It demonstrates pure Java compilation with manual dependency management.

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Why No Build Tool?

  • Educational simplicity: Focus on Java fundamentals
  • Minimal setup: No build configuration files needed
  • Single dependency: Only Gson JAR required
  • Transparent process: See exactly what happens during compilation

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Comparison with Build Tools

AspectManual CompilationMaven/Gradle
Setup complexityMinimalRequires build file
Dependencies1 JAR fileAutomatic download
Learning curveLowMedium-High
Build reproducibilityManualAutomated
Best forLearning, small projectsProduction, large teams

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Updating Gson

If you need to update Gson to a newer version:
1
Download the new version
2
Visit the Gson releases page and download the desired JAR file.
3
Replace the JAR file
4
cd source/lib
rm gson-2.10.1.jar
# Copy your new gson-X.X.X.jar to this directory
5
Update compilation commands
6
Modify the classpath in your build commands:
7
javac -cp "lib/gson-X.X.X.jar" -d out src/lad/com/alura/conversormoneda/**/*.java
java -cp "out:lib/gson-X.X.X.jar" lad.com.alura.conversormoneda.controladores.ConversorApp
8
Test the application
9
Run the application and verify all conversions work correctly.
Gson maintains backward compatibility across minor versions. Updating from 2.10.1 to 2.10.x should be seamless.

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Dependency Verification

Verify the Gson JAR is present: 
ls -lh source/lib/gson-2.10.1.jar
Expected output: ~277 KB file size

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API Dependency

External Service: ExchangeRate-API (v6) Endpoint: https://v6.exchangerate-api.com/v6/ Usage: Real-time currency conversion rates
The application requires an active internet connection to fetch current exchange rates. The API key is embedded in the source code for demonstration purposes.
Referenced in: src/lad/com/alura/conversormoneda/modelos/ConsultaMoneda.java:17

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