// A client for interacting with the Google Pay API.

private final PaymentsClient paymentsClient;

// LiveData with the result of whether the user can pay using Google Pay

private final MutableLiveData<Boolean> _canUseGooglePay = new MutableLiveData<>();

public CheckoutViewModel(@NonNull Application application) {

super(application);

paymentsClient = PaymentsUtil.createPaymentsClient(application);

fetchCanUseGooglePay();

}

public final LiveData<Boolean> canUseGooglePay = _canUseGooglePay;

/**

* Determine the user's ability to pay with a payment method supported by your app and display

* a Google Pay payment button.

*/

private void fetchCanUseGooglePay() {

final JSONObject isReadyToPayJson = PaymentsUtil.getIsReadyToPayRequest();

if (isReadyToPayJson == null) {

_canUseGooglePay.setValue(false);

return;

}

// The call to isReadyToPay is asynchronous and returns a Task. We need to provide an

// OnCompleteListener to be triggered when the result of the call is known.

IsReadyToPayRequest request = IsReadyToPayRequest.fromJson(isReadyToPayJson.toString());

Task<Boolean> task = paymentsClient.isReadyToPay(request);

task.addOnCompleteListener(

completedTask -> {

if (completedTask.isSuccessful()) {

_canUseGooglePay.setValue(completedTask.getResult());

} else {

Log.w("isReadyToPay failed", completedTask.getException());

_canUseGooglePay.setValue(false);

}

});

}

/**

* Creates a Task that starts the payment process with the transaction details included.

*

* @param priceCents the price to show on the payment sheet.

* @return a Task with the payment information.

*/

public Task<PaymentData> getLoadPaymentDataTask(final long priceCents) {

JSONObject paymentDataRequestJson = PaymentsUtil.getPaymentDataRequest(priceCents);

if (paymentDataRequestJson == null) {

return null;

}

PaymentDataRequest request =

PaymentDataRequest.fromJson(paymentDataRequestJson.toString());

return paymentsClient.loadPaymentData(request);

}

}