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The Currency Converter automatically tracks all your conversions in a history log, allowing you to review past transactions with detailed timestamps.

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Accessing History

To view your conversion history:
  1. From the main menu, select option 7
  2. The application displays all conversions made during the current session
  3. Press any key to return to the main menu
7) Historial de conversiones
History viewing is implemented in ConversorApp.java:32-41 and uses Java streams with lambda expressions for efficient display

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History Format

Each conversion record follows this format: 
[DD-MM-YYYY HH:mm:ss] AMOUNT BASE_CURRENCY =>> RESULT TARGET_CURRENCY

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Format Components

Timestamp

Date and time when the conversion was performed, formatted as day-month-year with 24-hour time

Original Amount

The amount you entered for conversion

Base Currency

The currency you converted from (e.g., USD, ARS, BRL, COP)

Result

The converted amount in the target currency

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Example History Output

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With Conversions

When you have performed conversions, the history displays: 
--- HISTORIAL DE CONVERSIONES ---
[05-03-2026 14:23:45] 100.0 USD =>> 35000.0 ARS
[05-03-2026 14:25:12] 50.0 USD =>> 247.75 BRL
[05-03-2026 14:27:33] 200.0 USD =>> 760000.0 COP
[05-03-2026 14:29:01] 500.0 ARS =>> 1.43 USD
---------------------------------
This shows four conversions performed during the session, each with its precise timestamp.

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Empty History

If no conversions have been performed yet, you’ll see: 
--- HISTORIAL DE CONVERSIONES ---
No hay conversiones recientes.
---------------------------------
Empty history check is handled in ConversorApp.java:34-36

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RegistroConversion Record Structure

History entries are stored using the RegistroConversion record class, which is a Java record type providing immutable data storage.

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Record Fields

record RegistroConversion(
    String monedaBase,      // Base currency code (e.g., "USD")
    String monedaObjetivo,  // Target currency code (e.g., "ARS")
    double cantidad,        // Amount converted
    double resultado,       // Conversion result
    LocalDateTime fechaHora // Timestamp of conversion
)
The RegistroConversion record is defined in /workspace/source/src/lad/com/alura/conversormoneda/modelos/RegistroConversion.java:6

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Custom toString() Method

The record overrides the toString() method to provide formatted output: 
@Override
public String toString() {
    DateTimeFormatter formato = DateTimeFormatter.ofPattern("dd-MM-yyyy HH:mm:ss");
    return "[" + fechaHora.format(formato) + "] " + cantidad + " " + 
           monedaBase + " =>> " + resultado + " " + monedaObjetivo;
}
This custom formatting ensures consistent, readable history output.
Custom toString() implementation is in RegistroConversion.java:9-13

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How History is Created

After each successful conversion:
  1. A new RegistroConversion object is created with:
    • Base currency code
    • Target currency code
    • Original amount
    • Conversion result
    • Current timestamp (LocalDateTime.now())
  2. The record is added to the historial ArrayList
  3. The list persists for the entire session 
RegistroConversion registro = new RegistroConversion(
    base, objetivo, cantidad, resultado, LocalDateTime.now()
);
historial.add(registro);
History creation happens in ConversorApp.java:83-84 after each conversion

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History Persistence

The history is stored in memory using an ArrayList<RegistroConversion> and persists only during the current application session. When you exit the application (option 8), the history is cleared.
The history list is initialized at application startup: 
List<RegistroConversion> historial = new ArrayList<>();
History list initialization is in ConversorApp.java:18

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Using Lambda Expressions

The history display uses Java’s functional programming features: 
historial.forEach(System.out::println);
This lambda expression iterates through all records and prints each one using the custom toString() method, providing clean and efficient code.
Lambda-based display is implemented in ConversorApp.java:37

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