> For the complete documentation index, see [llms.txt](https://docs.payments.thalescloud.io/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://docs.payments.thalescloud.io/nfc-wallet-sdk-android/es/implement-nfc-wallet/make-payment/implement-contactless-payments/6.-display-transaction-context.md).

# 6. Mostrar el contexto de la transacción

## Resumen

Después de cada transacción, su **aplicación de billetera digital** puede mostrar los detalles de la transacción.

El SDK de Billetera NFC proporciona un `TransactionContext` en estos callbacks:

* `ContactlessPaymentServiceListener.onTransactionCompleted()`
* `ContactlessPaymentServiceListener.onError()`

{% hint style="warning" %}
Trate `TransactionContext` como datos sensibles.

Llamar `TransactionContext.wipe()` después de que haya terminado de usarlo.
{% endhint %}

## Integración del SDK

### Leer y formatear los detalles de la transacción

Lea los valores que necesita del contexto y luego formátelos para mostrarlos.

{% code title="MyPaymentListener.java" expandable="true" %}

```java
@Override
public void onTransactionCompleted(TransactionContext ctx) {
    try {
        TransactionData data = TransactionData.from(ctx);
        // Mostrar datos en su UI.
    } finally {
        ctx.wipe();
    }
}

@Override
public void onError(
        TransactionContext ctx,
        PaymentServiceErrorCode errorCode,
        String message) {

    if (ctx == null) {
        // Manejar el error cuando no hay contexto de transacción disponible.
        return;
    }

    try {
        TransactionData data = TransactionData.from(ctx);
        // Mostrar datos y detalles del error en su UI.
    } finally {
        ctx.wipe();
    }
}

/**
 * Clase de datos de conveniencia para la visualización de transacciones.
 */
public class TransactionData {

    private final String currencyCode;
    private final double amount;
    private final String transactionDate;
    private final String transactionType;
    private final String transactionId;

    private TransactionData(
            String currencyCode,
            double amount,
            String transactionDate,
            String transactionType,
            String transactionId) {
        this.currencyCode = currencyCode;
        this.amount = amount;
        this.transactionDate = transactionDate;
        this.transactionType = transactionType;
        this.transactionId = transactionId;
    }

    public static TransactionData from(TransactionContext ctx) {
        String currencyCode = TransactionDisplayUtils.bcdToString(ctx.getCurrencyCode());
        String transactionDate = TransactionDisplayUtils.bcdToString(ctx.getTrxDate());
        String transactionType = TransactionDisplayUtils.getTransactionType(ctx.getTrxType());

        return new TransactionData(
                currencyCode,
                ctx.getAmount(),
                transactionDate,
                transactionType,
                ctx.getTrxId());
    }

    public String getCurrencyCode() {
        return currencyCode;
    }

    public double getAmount() {
        return amount;
    }

    public String getTransactionDate() {
        return transactionDate;
    }

    public String getTransactionType() {
        return transactionType;
    }

    public String getTransactionId() {
        return transactionId;
    }
}
```

{% endcode %}

### Convertir valores BCD para su visualización (utilidad)

La siguiente utilidad convierte valores codificados en BCD a cadenas.

Ajuste el formato para que coincida con su UI y con los requisitos de su red de pagos.

{% code title="TransactionDisplayUtils.java" expandable="true" %}

```java
public final class TransactionDisplayUtils {

    private TransactionDisplayUtils() {
        // Clase de utilidad.
    }

    public static String bcdToString(byte[] bcd) {
        if (bcd == null) {
            return "";
        }

        StringBuilder sb = new StringBuilder();
        for (byte b : bcd) {
            sb.append(bcdToString(b));
        }
        return sb.toString();
    }

    public static String bcdToString(byte bcd) {
        int high = (bcd & 0xF0) >>> 4;
        int low = (bcd & 0x0F);
        return String.valueOf(high) + low;
    }

    public static String getTransactionType(byte trxType) {
        switch (trxType) {
            case 0:
                return "PAY";
            case 32:
                return "REFUND";
            default:
                return "TRANSACTION";
        }
    }
}
```

{% endcode %}


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