Tutorial

Follow the steps in this tutorial to add Google Pay to your Android application and configure it to accept payment cards.

Step 1: Define your payment configuration

Configure your Google Pay API version

Declare the version of the Google Pay API that your application uses. The major and minor versions affect the fields expected in each passed object and are included in the response.

Create a base request object that contains properties that are present in all other request objects.

KotlinJava
private val baseRequest = JSONObject()
    .put("apiVersion", 2)
    .put("apiVersionMinor", 0)
PaymentsUtil.kt

    
private static JSONObject getBaseRequest() throws JSONException {
  return new JSONObject()
      .put("apiVersion", 2)
      .put("apiVersionMinor", 0);
}
PaymentsUtil.java

Request a payment token for your payment provider

Google encrypts information about a payer's selected card for secure processing by a payment provider.

KotlinJava
private fun gatewayTokenizationSpecification(): JSONObject {
    return JSONObject().apply {
        put("type", "PAYMENT_GATEWAY")
        put("parameters", JSONObject(mapOf(
                "gateway" to "example",
                "gatewayMerchantId" to "exampleGatewayMerchantId")))
    }
}
    
private static JSONObject getGatewayTokenizationSpecification() throws JSONException {
  return new JSONObject()
      .put("type", "PAYMENT_GATEWAY")
      .put("parameters", new JSONObject()
          .put("gateway", "example")
          .put("gatewayMerchantId", "exampleGatewayMerchantId")
      );
}
PaymentsUtil.java

Replace example and exampleGatewayMerchantId with the appropriate values for your payment provider. Use the following table to find the specific gateway and gatewayMerchantId values for your payment provider:

Gateway Parameters and documents
ABA PayWay 
  "gateway": "ababank"
  "gatewayMerchantId": "YOUR_GATEWAY_MERCHANT_ID"

Developer docs
accept.blue 
  "gateway": "acceptblue"
  "gatewayMerchantId": "YOUR_GATEWAY_MERCHANT_ID"

Developer docs
ACI 
  "gateway": "aciworldwide"
  "gatewayMerchantId": "YOUR_ENTITY_ID"

Developer docs
ACpay 
  "gateway": "acpay"
  "gatewayMerchantId": "YOUR_GATEWAY_MERCHANT_ID"

Developer docs
Acquired.com 
  "gateway": "acquired"
  "gatewayMerchantId": "YOUR_GATEWAY_MERCHANT_ID"

Developer docs
12345…91

The PAYMENT_GATEWAY tokenization type is the most common merchant implementation of the card payment method in the Google Pay API. If your payment provider isn't supported, you might be able to accept Google Pay by a DIRECT integration. For more information, see the Direct tokenization documentation.

Define supported payment card networks

Define the card networks that your application accepts.

KotlinJava
private val allowedCardNetworks = JSONArray(listOf(
        "AMEX",
        "DISCOVER",
        "INTERAC",
        "JCB",
        "MASTERCARD",
        "VISA"))
    
private static JSONArray getAllowedCardNetworks() {
  return new JSONArray()
      .put("AMEX")
      .put("DISCOVER")
      .put("INTERAC")
      .put("JCB")
      .put("MASTERCARD")
      .put("VISA");
}

The Google Pay API might return cards on file from your account (PAN_ONLY) or a device token on an Android-powered device authenticated with a 3-D Secure cryptogram (CRYPTOGRAM_3DS). You can configure the API to return the methods that your application supports.

Before you set allowedCardAuthMethods, confirm with your payment processor and acquirer on whether device tokens (CRYPTOGRAM_3DS) are supported in your region.

KotlinJava
private val allowedCardAuthMethods = JSONArray(listOf(
        "PAN_ONLY",
        "CRYPTOGRAM_3DS"))
    
private static JSONArray getAllowedCardAuthMethods() {
  return new JSONArray()
      .put("PAN_ONLY")
      .put("CRYPTOGRAM_3DS");
}

For more information, see the reference documentation for the CardParameters object. For Android device tokens support, check with your gateway or processor for the card networks supported.

Describe your allowed payment methods

In order to describe your application's support for the CARD payment method, combine your supported authentication methods and card networks.

KotlinJava
private fun baseCardPaymentMethod(): JSONObject =
    JSONObject()
        .put("type", "CARD")
        .put("parameters", JSONObject()
                .put("allowedAuthMethods", allowedCardAuthMethods)
                .put("allowedCardNetworks", allowedCardNetworks)
                .put("billingAddressRequired", true)
                .put("billingAddressParameters", JSONObject()
                        .put("format", "FULL")
                )
        )
PaymentsUtil.kt

    
private static JSONObject getBaseCardPaymentMethod() throws JSONException {
  return new JSONObject()
      .put("type", "CARD")
      .put("parameters", new JSONObject()
          .put("allowedAuthMethods", getAllowedCardAuthMethods())
          .put("allowedCardNetworks", getAllowedCardNetworks())
          .put("billingAddressRequired", true)
          .put("billingAddressParameters", new JSONObject()
              .put("format", "FULL")
          )
      );
}
PaymentsUtil.java

Extend your configuration with information about how to tokenize the payment method.

KotlinJava
private val cardPaymentMethod: JSONObject = baseCardPaymentMethod()
    .put("tokenizationSpecification", gatewayTokenizationSpecification)
PaymentsUtil.kt

    
private static JSONObject getCardPaymentMethod() throws JSONException {
  return getBaseCardPaymentMethod()
      .put("tokenizationSpecification", getGatewayTokenizationSpecification());
}
PaymentsUtil.java

For more information, see the reference documentation for the CardParameters object.

Step 2: Create a PaymentsClient instance

Create a PaymentsClient instance to interact with the Google Pay API.

KotlinJava
fun createPaymentsClient(context: Context): PaymentsClient {
    val walletOptions = Wallet.WalletOptions.Builder()
        .setEnvironment(Constants.PAYMENTS_ENVIRONMENT)
        .build()

    return Wallet.getPaymentsClient(context, walletOptions)
}
PaymentsUtil.kt

    
public static PaymentsClient createPaymentsClient(Context context) {
  Wallet.WalletOptions walletOptions =
      new Wallet.WalletOptions.Builder().setEnvironment(Constants.PAYMENTS_ENVIRONMENT).build();
  return Wallet.getPaymentsClient(context, walletOptions);
}
PaymentsUtil.java

Step 3: Determine readiness to pay with the Google Pay API

Add your allowed payment methods to your base request object with the following code snippet:

KotlinJava
fun isReadyToPayRequest(): JSONObject? =
    try {
        baseRequest
            .put("allowedPaymentMethods", JSONArray().put(baseCardPaymentMethod()))
    } catch (e: JSONException) {
        null
    }
PaymentsUtil.kt

    
public static JSONObject getIsReadyToPayRequest() {
  try {
    return getBaseRequest()
        .put("allowedPaymentMethods", new JSONArray().put(getBaseCardPaymentMethod()));
  } catch (JSONException e) {
    return null;
  }
}
PaymentsUtil.java

Before you display the Google Pay button, call the isReadyToPay API to determine if the user can make payments with the Google Pay API. For a full list of configuration properties, see the IsReadyToPayRequest JSON object documentation.

KotlinKotlinJava
private fun possiblyShowGooglePayButton() {

    val isReadyToPayJson = PaymentsUtil.isReadyToPayRequest() ?: return
    val request = IsReadyToPayRequest.fromJson(isReadyToPayJson.toString()) ?: 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.
    val task = paymentsClient.isReadyToPay(request)
    task.addOnCompleteListener { completedTask ->
        try {
            completedTask.getResult(ApiException::class.java)?.let(::setGooglePayAvailable)
        } catch (exception: ApiException) {
            // Process error
            Log.w("isReadyToPay failed", exception)
        }
    }
}
CheckoutActivity.kt

      
private suspend fun fetchCanUseGooglePay(): Boolean {
    val request = IsReadyToPayRequest.fromJson(PaymentsUtil.isReadyToPayRequest().toString())
    return paymentsClient.isReadyToPay(request).await()
}
CheckoutViewModel.kt

      
private void possiblyShowGooglePayButton() {

  final Optional<JSONObject> isReadyToPayJson = PaymentsUtil.getIsReadyToPayRequest();
  if (!isReadyToPayJson.isPresent()) {
    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.get().toString());
  Task<Boolean> task = paymentsClient.isReadyToPay(request);
  task.addOnCompleteListener(this,
      new OnCompleteListener<Boolean>() {
        @Override
        public void onComplete(@NonNull Task<Boolean> task) {
          if (task.isSuccessful()) {
            setGooglePayAvailable(task.getResult());
          } else {
            Log.w("isReadyToPay failed", task.getException());
          }
        }
      });
}
CheckoutActivity.java

Step 4: Add a Google Pay payment button

Add a Google Pay payment button to your app to encourage shoppers to check out with payment methods that are supported by the Google Pay API and your app.

For more information about available button types, colors, and display requirements, see the ButtonOptions reference.

Add the PayButton layout to your application's checkout layout:

KotlinXML
PayButton(
    modifier = Modifier
        .testTag("payButton")
        .fillMaxWidth(),
    onClick = onGooglePayButtonClick,
    allowedPaymentMethods = PaymentsUtil.allowedPaymentMethods.toString()
CheckoutLayout.kt

      
<com.google.android.gms.wallet.button.PayButton
        android:id="@+id/googlePayButton"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:layout_marginBottom="20dp"/>
">activity_checkout.xml

If you are adding the Google Pay button using XML...

Go to the Android activity and initialize the Google Pay button alongside other UI elements:

KotlinJava
override fun onCreate(savedInstanceState: Bundle?) {
  super.onCreate(savedInstanceState)

  // Use view binding to access the UI elements
  layout = ActivityCheckoutBinding.inflate(layoutInflater)
  setContentView(layout.root)

  // Setup buttons
  googlePayButton = layout.googlePayButton
  googlePayButton.initialize(
      ButtonOptions.newBuilder()
          .setAllowedPaymentMethods(PaymentsUtil.allowedPaymentMethods.toString()).build()
  )
  googlePayButton.setOnClickListener { requestPayment() }

  // Check Google Pay availability
  model.canUseGooglePay.observe(this, Observer(::setGooglePayAvailable))
}
      
private void initializeUi() {

  // Use view binding to access the UI elements
  ActivityCheckoutBinding layoutBinding = ActivityCheckoutBinding.inflate(getLayoutInflater());
  setContentView(layoutBinding.getRoot());

  // The Google Pay button is a layout file – take the root view
  googlePayButton = layoutBinding.googlePayButton;
  try {
    googlePayButton.initialize(
        ButtonOptions.newBuilder()
            .setAllowedPaymentMethods(PaymentsUtil.getAllowedPaymentMethods().toString()).build()
    );
    googlePayButton.setOnClickListener(this::requestPayment);
  } catch (JSONException e) {
    // Keep Google Pay button hidden (consider logging this to your app analytics service)
  }
}
CheckoutActivity.java

Step 5: Create a PaymentDataRequest object

A PaymentDataRequest JSON object describes the information that you request from a payer in a Google Pay payment sheet. This includes information about the transaction price and the status of the provided price. For more information, see TransactionInfo JSON object documentation.

The following blocks add information about the merchant and the transaction to the PaymentDataRequest object needed to start the payment process with Google Pay.

KotlinJava
private fun getTransactionInfo(price: String): JSONObject =
    JSONObject()
        .put("totalPrice", price)
        .put("totalPriceStatus", "FINAL")
        .put("countryCode", Constants.COUNTRY_CODE)
        .put("currencyCode", Constants.CURRENCY_CODE)
PaymentsUtil.kt

    
private static JSONObject getTransactionInfo(String price) throws JSONException {
  return new JSONObject()
      .put("totalPrice", price)
      .put("totalPriceStatus", "FINAL")
      .put("countryCode", Constants.COUNTRY_CODE)
      .put("currencyCode", Constants.CURRENCY_CODE)
      .put("checkoutOption", "COMPLETE_IMMEDIATE_PURCHASE");
}
PaymentsUtil.java
KotlinJava
private val merchantInfo: JSONObject =
    JSONObject().put("merchantName", "Example Merchant")
PaymentsUtil.kt

    
private static JSONObject getMerchantInfo() throws JSONException {
  return new JSONObject().put("merchantName", "Example Merchant");
}
PaymentsUtil.java

Assign your base request object to a new PaymentDataRequest JSON object. Then, add the payment methods supported by your application, such as any configuration of additional data expected in the response. Finally, add information about the transaction and the merchant who makes the request:

KotlinJava
fun getPaymentDataRequest(priceLabel: String): JSONObject =
    baseRequest
        .put("allowedPaymentMethods", allowedPaymentMethods)
        .put("transactionInfo", getTransactionInfo(priceLabel))
        .put("merchantInfo", merchantInfo)
        .put("shippingAddressRequired", true)
        .put("shippingAddressParameters", JSONObject()
                .put("phoneNumberRequired", false)
                .put("allowedCountryCodes", JSONArray(listOf("US", "GB")))
        )
PaymentsUtil.kt

    
public static JSONObject getPaymentDataRequest(String priceLabel) {
  try {
    return PaymentsUtil.getBaseRequest()
        .put("allowedPaymentMethods", getAllowedPaymentMethods())
        .put("transactionInfo", getTransactionInfo(priceLabel))
        .put("merchantInfo", getMerchantInfo())
        .put("shippingAddressRequired", true)
        .put("shippingAddressParameters", new JSONObject()
            .put("phoneNumberRequired", false)
            .put("allowedCountryCodes", new JSONArray(Constants.SHIPPING_SUPPORTED_COUNTRIES))
        );

  } catch (JSONException e) {
    return null;
  }
}
PaymentsUtil.java

The PaymentDataRequest object is a Parcelable that represents a payment data request. The PaymentDataRequest provides information that's necessary in order to support a payment.

For more information, see the PaymentDataRequest JSON object documentation.

Step 6: Initiate the payment process with Google Pay

To start the payment process, call the loadPaymentData request using the PaymentsClient object. This call returns a Task object with the result of the operation.

First, create the loadPaymentData task, using the request created in the previous step:

KotlinJava
fun getLoadPaymentDataTask(priceLabel: String): Task<PaymentData> {
    val paymentDataRequestJson = PaymentsUtil.getPaymentDataRequest(priceLabel)
    val request = PaymentDataRequest.fromJson(paymentDataRequestJson.toString())
    return paymentsClient.loadPaymentData(request)
}
CheckoutViewModel.kt

    
public Task<PaymentData> getLoadPaymentDataTask(String priceLabel) {
    JSONObject paymentDataRequestJson = PaymentsUtil.getPaymentDataRequest(priceLabel);
    if (paymentDataRequestJson == null) {
        return null;
    }

    PaymentDataRequest request =
            PaymentDataRequest.fromJson(paymentDataRequestJson.toString());
    return paymentsClient.loadPaymentData(request);
}
 getLoadPaymentDataTask">CheckoutViewModel.java

To process the result, use one of the activity result contracts in the API. This example uses GetPaymentDataResult which yields an object with information about the operation in addition to the result itself:

KotlinJava
private val paymentDataLauncher = registerForActivityResult(GetPaymentDataResult()) { taskResult ->
    when (taskResult.status.statusCode) {
        CommonStatusCodes.SUCCESS -> {
            taskResult.result!!.let {
                Log.i("Google Pay result:", it.toJson())
                model.setPaymentData(it)
            }
        }
        //CommonStatusCodes.CANCELED -> The user canceled
        //CommonStatusCodes.DEVELOPER_ERROR -> The API returned an error (it.status: Status)
        //else -> Handle internal and other unexpected errors
    }
}
CheckoutActivity.kt

    
private final ActivityResultLauncher<Task<PaymentData>> paymentDataLauncher =
    registerForActivityResult(new GetPaymentDataResult(), result -> {
      int statusCode = result.getStatus().getStatusCode();
      switch (statusCode) {
        case CommonStatusCodes.SUCCESS:
          handlePaymentSuccess(result.getResult());
          break;
        //case CommonStatusCodes.CANCELED: The user canceled
        case CommonStatusCodes.DEVELOPER_ERROR:
          handleError(statusCode, result.getStatus().getStatusMessage());
          break;
        default:
          handleError(statusCode, "Unexpected non API" +
              " exception when trying to deliver the task result to an activity!");
          break;
      }
    });
> paymentDataLauncher">CheckoutActivity.java

Before presenting the user with a confirmation of their purchase, extract the payment token from the PaymentData result object, and use this token to create the payment transaction with your gateway.

For more information about the result object, see the PaymentData JSON object reference.

Now, use the activity result launcher and the task to show the Google Pay payment selector:

KotlinKotlinJava
private fun requestPayment() {
    val task = model.getLoadPaymentDataTask(priceLabel = "50.2")
    task.addOnCompleteListener(paymentDataLauncher::launch)
}
CheckoutActivity.kt

      
private fun requestPayment() {
    lifecycleScope.launch {
        val task = model.getLoadPaymentDataTask(priceLabel = "50.2")
        paymentDataLauncher.launch(task.awaitTask())
    }
}
CheckoutActivity.kt

      
public void requestPayment(View view) {
  // The price provided to the API should include taxes and shipping.
  final Task<PaymentData> task = model.getLoadPaymentDataTask("50.2");
  task.addOnCompleteListener(paymentDataLauncher::launch);
}
CheckoutActivity.java

Put it all together

The following snippet shows a complete example for a properly configured project. For the project-level setup steps, see Configure your project.

Kotlin

ActivityUtilView modelConstants
/*
 * Copyright 2024 Google Inc.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package com.google.android.gms.samples.pay.activity

import android.os.Bundle
import android.util.Log
import androidx.activity.ComponentActivity
import androidx.activity.compose.setContent
import androidx.activity.viewModels
import androidx.compose.runtime.getValue
import androidx.lifecycle.compose.collectAsStateWithLifecycle
import androidx.lifecycle.lifecycleScope
import com.google.android.gms.common.api.CommonStatusCodes
import com.google.android.gms.wallet.contract.TaskResultContracts.GetPaymentDataResult
import com.google.android.gms.samples.pay.R
import com.google.android.gms.samples.pay.ui.ProductScreen
import com.google.android.gms.samples.pay.viewmodel.CheckoutViewModel
import com.google.android.gms.samples.pay.viewmodel.PaymentUiState
import com.google.android.gms.samples.pay.viewmodel.awaitTask
import kotlinx.coroutines.launch

class CheckoutActivity : ComponentActivity() {

    private val paymentDataLauncher = registerForActivityResult(GetPaymentDataResult()) { taskResult ->
        when (taskResult.status.statusCode) {
            CommonStatusCodes.SUCCESS -> {
                taskResult.result!!.let {
                    Log.i("Google Pay result:", it.toJson())
                    model.setPaymentData(it)
                }
            }
            //CommonStatusCodes.CANCELED -> The user canceled
            //CommonStatusCodes.DEVELOPER_ERROR -> The API returned an error (it.status: Status)
            //else -> Handle internal and other unexpected errors
        }
    }

    private val model: CheckoutViewModel by viewModels()
    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)

        setContent {
            val payState: PaymentUiState by model.paymentUiState.collectAsStateWithLifecycle()
            ProductScreen(
                title = "Men's Tech Shell Full-Zip",
                description = "A versatile full-zip that you can wear all day long and even...",
                price = "$50.20",
                image = R.drawable.ts_10_11019a,
                payUiState = payState,
                onGooglePayButtonClick = this::requestPayment,
            )
        }
    }

    private fun requestPayment() {
        val task = model.getLoadPaymentDataTask(priceLabel = "50.2")
        task.addOnCompleteListener(paymentDataLauncher::launch)
    }
}
CheckoutActivity.kt

    
/*
 * Copyright 2024 Google Inc.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package com.google.android.gms.samples.pay.util

import android.content.Context
import com.google.android.gms.samples.pay.Constants
import com.google.android.gms.wallet.PaymentsClient
import com.google.android.gms.wallet.Wallet
import org.json.JSONArray
import org.json.JSONException
import org.json.JSONObject
import java.math.BigDecimal
import java.math.RoundingMode

/**
 * Contains helper static methods for dealing with the Payments API.
 *
 * Many of the parameters used in the code are optional and are set here merely to call out their
 * existence. Please consult the documentation to learn more and feel free to remove ones not
 * relevant to your implementation.
 */
object PaymentsUtil {

    /**
     * Create a Google Pay API base request object with properties used in all requests.
     *
     * @return Google Pay API base request object.
     * @throws JSONException
     */
    private val baseRequest = JSONObject()
        .put("apiVersion", 2)
        .put("apiVersionMinor", 0)

    /**
     * Gateway Integration: Identify your gateway and your app's gateway merchant identifier.
     *
     *
     * The Google Pay API response will return an encrypted payment method capable of being charged
     * by a supported gateway after payer authorization.
     *
     *
     * TODO: Check with your gateway on the parameters to pass and modify them in Constants.java.
     *
     * @return Payment data tokenization for the CARD payment method.
     * @throws JSONException
     * See [PaymentMethodTokenizationSpecification](https://developers.google.com/pay/api/android/reference/object.PaymentMethodTokenizationSpecification)
     */
    private val gatewayTokenizationSpecification: JSONObject =
        JSONObject()
            .put("type", "PAYMENT_GATEWAY")
            .put("parameters", JSONObject(Constants.PAYMENT_GATEWAY_TOKENIZATION_PARAMETERS))

    /**
     * Card networks supported by your app and your gateway.
     *
     *
     * TODO: Confirm card networks supported by your app and gateway & update in Constants.java.
     *
     * @return Allowed card networks
     * See [CardParameters](https://developers.google.com/pay/api/android/reference/object.CardParameters)
     */
    private val allowedCardNetworks = JSONArray(Constants.SUPPORTED_NETWORKS)

    /**
     * Card authentication methods supported by your app and your gateway.
     *
     *
     * TODO: Confirm your processor supports Android device tokens on your supported card networks
     * and make updates in Constants.java.
     *
     * @return Allowed card authentication methods.
     * See [CardParameters](https://developers.google.com/pay/api/android/reference/object.CardParameters)
     */
    private val allowedCardAuthMethods = JSONArray(Constants.SUPPORTED_METHODS)

    /**
     * Describe your app's support for the CARD payment method.
     *
     *
     * The provided properties are applicable to both an IsReadyToPayRequest and a
     * PaymentDataRequest.
     *
     * @return A CARD PaymentMethod object describing accepted cards.
     * @throws JSONException
     * See [PaymentMethod](https://developers.google.com/pay/api/android/reference/object.PaymentMethod)
     */
    // Optionally, you can add billing address/phone number associated with a CARD payment method.
    private fun baseCardPaymentMethod(): JSONObject =
        JSONObject()
            .put("type", "CARD")
            .put("parameters", JSONObject()
                    .put("allowedAuthMethods", allowedCardAuthMethods)
                    .put("allowedCardNetworks", allowedCardNetworks)
                    .put("billingAddressRequired", true)
                    .put("billingAddressParameters", JSONObject()
                            .put("format", "FULL")
                    )
            )

    /**
     * Describe the expected returned payment data for the CARD payment method
     *
     * @return A CARD PaymentMethod describing accepted cards and optional fields.
     * @throws JSONException
     * See [PaymentMethod](https://developers.google.com/pay/api/android/reference/object.PaymentMethod)
     */
    private val cardPaymentMethod: JSONObject = baseCardPaymentMethod()
        .put("tokenizationSpecification", gatewayTokenizationSpecification)

    val allowedPaymentMethods: JSONArray = JSONArray().put(cardPaymentMethod)

    /**
     * An object describing accepted forms of payment by your app, used to determine a viewer's
     * readiness to pay.
     *
     * @return API version and payment methods supported by the app.
     * See [IsReadyToPayRequest](https://developers.google.com/pay/api/android/reference/object.IsReadyToPayRequest)
     */
    fun isReadyToPayRequest(): JSONObject? =
        try {
            baseRequest
                .put("allowedPaymentMethods", JSONArray().put(baseCardPaymentMethod()))
        } catch (e: JSONException) {
            null
        }

    /**
     * Information about the merchant requesting payment information
     *
     * @return Information about the merchant.
     * @throws JSONException
     * See [MerchantInfo](https://developers.google.com/pay/api/android/reference/object.MerchantInfo)
     */
    private val merchantInfo: JSONObject =
        JSONObject().put("merchantName", "Example Merchant")

    /**
     * Creates an instance of [PaymentsClient] for use in an [Context] using the
     * environment and theme set in [Constants].
     *
     * @param context from the caller activity.
     */
    fun createPaymentsClient(context: Context): PaymentsClient {
        val walletOptions = Wallet.WalletOptions.Builder()
            .setEnvironment(Constants.PAYMENTS_ENVIRONMENT)
            .build()

        return Wallet.getPaymentsClient(context, walletOptions)
    }

    /**
     * Provide Google Pay API with a payment amount, currency, and amount status.
     *
     * @return information about the requested payment.
     * @throws JSONException
     * See [TransactionInfo](https://developers.google.com/pay/api/android/reference/object.TransactionInfo)
     */
    private fun getTransactionInfo(price: String): JSONObject =
        JSONObject()
            .put("totalPrice", price)
            .put("totalPriceStatus", "FINAL")
            .put("countryCode", Constants.COUNTRY_CODE)
            .put("currencyCode", Constants.CURRENCY_CODE)

    /**
     * An object describing information requested in a Google Pay payment sheet
     *
     * @return Payment data expected by your app.
     * See [PaymentDataRequest](https://developers.google.com/pay/api/android/reference/object.PaymentDataRequest)
     */
    fun getPaymentDataRequest(priceLabel: String): JSONObject =
        baseRequest
            .put("allowedPaymentMethods", allowedPaymentMethods)
            .put("transactionInfo", getTransactionInfo(priceLabel))
            .put("merchantInfo", merchantInfo)
            .put("shippingAddressRequired", true)
            .put("shippingAddressParameters", JSONObject()
                    .put("phoneNumberRequired", false)
                    .put("allowedCountryCodes", JSONArray(listOf("US", "GB")))
            )
}

PaymentsUtil.kt

      
/*
 * Copyright 2024 Google Inc.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package com.google.android.gms.samples.pay.viewmodel

import android.app.Application
import android.util.Log
import androidx.lifecycle.AndroidViewModel
import androidx.lifecycle.viewModelScope
import com.google.android.gms.common.api.ApiException
import com.google.android.gms.common.api.CommonStatusCodes
import com.google.android.gms.samples.pay.util.PaymentsUtil
import com.google.android.gms.tasks.CancellationTokenSource
import com.google.android.gms.tasks.Task
import com.google.android.gms.wallet.IsReadyToPayRequest
import com.google.android.gms.wallet.PaymentData
import com.google.android.gms.wallet.PaymentDataRequest
import com.google.android.gms.wallet.PaymentsClient
import kotlinx.coroutines.flow.MutableStateFlow
import kotlinx.coroutines.flow.StateFlow
import kotlinx.coroutines.flow.asStateFlow
import kotlinx.coroutines.flow.update
import kotlinx.coroutines.launch
import kotlinx.coroutines.suspendCancellableCoroutine
import kotlinx.coroutines.tasks.await
import org.json.JSONException
import org.json.JSONObject
import java.util.concurrent.Executor
import kotlin.coroutines.resume

class CheckoutViewModel(application: Application) : AndroidViewModel(application) {

    private val _paymentUiState: MutableStateFlow<PaymentUiState> =
        MutableStateFlow(PaymentUiState.NotStarted)
    val paymentUiState: StateFlow<PaymentUiState> = _paymentUiState.asStateFlow()

    // A client for interacting with the Google Pay API.
    private val paymentsClient: PaymentsClient = PaymentsUtil.createPaymentsClient(application)

    init {
        viewModelScope.launch {
            verifyGooglePayReadiness()
        }
    }

    /**
     * Determine the user's ability to pay with a payment method supported by your app and display
     * a Google Pay payment button.
    ) */
    private suspend fun verifyGooglePayReadiness() {
        val newUiState: PaymentUiState = try {
            if (fetchCanUseGooglePay()) {
                PaymentUiState.Available
            } else {
                PaymentUiState.Error(CommonStatusCodes.ERROR)
            }
        } catch (exception: ApiException) {
            PaymentUiState.Error(exception.statusCode, exception.message)
        }

        _paymentUiState.update { newUiState }
    }

    /**
     * Determine the user's ability to pay with a payment method supported by your app.
    ) */
    private suspend fun fetchCanUseGooglePay(): Boolean {
        val request = IsReadyToPayRequest.fromJson(PaymentsUtil.isReadyToPayRequest().toString())
        return paymentsClient.isReadyToPay(request).await()
    }

    /**
     * Creates a [Task] that starts the payment process with the transaction details included.
     *
     * @return a [Task] with the payment information.
     * @see [PaymentDataRequest](https://developers.google.com/android/reference/com/google/android/gms/wallet/PaymentsClient#loadPaymentData(com.google.android.gms.wallet.PaymentDataRequest)
    ) */
    fun getLoadPaymentDataTask(priceLabel: String): Task<PaymentData> {
        val paymentDataRequestJson = PaymentsUtil.getPaymentDataRequest(priceLabel)
        val request = PaymentDataRequest.fromJson(paymentDataRequestJson.toString())
        return paymentsClient.loadPaymentData(request)
    }

    /**
     * At this stage, the user has already seen a popup informing them an error occurred. Normally,
     * only logging is required.
     *
     * @param statusCode will hold the value of any constant from CommonStatusCode or one of the
     * WalletConstants.ERROR_CODE_* constants.
     * @see [
     * Wallet Constants Library](https://developers.google.com/android/reference/com/google/android/gms/wallet/WalletConstants.constant-summary)
     */
    private fun handleError(statusCode: Int, message: String?) {
        Log.e("Google Pay API error", "Error code: $statusCode, Message: $message")
    }

    fun setPaymentData(paymentData: PaymentData) {
        val payState = extractPaymentBillingName(paymentData)?.let {
            PaymentUiState.PaymentCompleted(payerName = it)
        } ?: PaymentUiState.Error(CommonStatusCodes.INTERNAL_ERROR)

        _paymentUiState.update { payState }
    }

    private fun extractPaymentBillingName(paymentData: PaymentData): String? {
        val paymentInformation = paymentData.toJson()

        try {
            // Token will be null if PaymentDataRequest was not constructed using fromJson(String).
            val paymentMethodData =
                JSONObject(paymentInformation).getJSONObject("paymentMethodData")
            val billingName = paymentMethodData.getJSONObject("info")
                .getJSONObject("billingAddress").getString("name")
            Log.d("BillingName", billingName)

            // Logging token string.
            Log.d(
                "Google Pay token", paymentMethodData
                    .getJSONObject("tokenizationData")
                    .getString("token")
            )

            return billingName
        } catch (error: JSONException) {
            Log.e("handlePaymentSuccess", "Error: $error")
        }

        return null
    }
}

abstract class PaymentUiState internal constructor() {
    object NotStarted : PaymentUiState()
    object Available : PaymentUiState()
    class PaymentCompleted(val payerName: String) : PaymentUiState()
    class Error(val code: Int, val message: String? = null) : PaymentUiState()
}

suspend fun <T> Task<T>.awaitTask(cancellationTokenSource: CancellationTokenSource? = null): Task<T> {
    return if (isComplete) this else suspendCancellableCoroutine { cont ->
        // Run the callback directly to avoid unnecessarily scheduling on the main thread.
        addOnCompleteListener(DirectExecutor, cont::resume)

        cancellationTokenSource?.let { cancellationSource ->
            cont.invokeOnCancellation { cancellationSource.cancel() }
        }
    }
}

/**
 * An [Executor] that just directly executes the [Runnable].
 */
private object DirectExecutor : Executor {
    override fun execute(r: Runnable) {
        r.run()
    }
}

CheckoutViewModel.kt

    
/*
 * Copyright 2024 Google Inc.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package com.google.android.gms.samples.pay

import com.google.android.gms.wallet.WalletConstants

/**
 * This file contains several constants you must edit before proceeding.
 * Please take a look at PaymentsUtil.java to see where the constants are used and to potentially
 * remove ones not relevant to your integration.
 *
 *
 * Required changes:
 *
 *  1.  Update SUPPORTED_NETWORKS and SUPPORTED_METHODS if required (consult your processor if
 * unsure)
 *  1.  Update CURRENCY_CODE to the currency you use.
 *  1.  Update SHIPPING_SUPPORTED_COUNTRIES to list the countries where you currently ship. If this
 * is not applicable to your app, remove the relevant bits from PaymentsUtil.java.
 *  1.  If you're integrating with your `PAYMENT_GATEWAY`, update
 * PAYMENT_GATEWAY_TOKENIZATION_NAME and PAYMENT_GATEWAY_TOKENIZATION_PARAMETERS per the
 * instructions they provided. You don't need to update DIRECT_TOKENIZATION_PUBLIC_KEY.
 *  1.  If you're using `DIRECT` integration, please edit protocol version and public key as
 * per the instructions.
 */
object Constants {
    /**
     * Changing this to ENVIRONMENT_PRODUCTION will make the API return chargeable card information.
     * Please refer to the documentation to read about the required steps needed to enable
     * ENVIRONMENT_PRODUCTION.
     *
     * @value #PAYMENTS_ENVIRONMENT
     */
    const val PAYMENTS_ENVIRONMENT = WalletConstants.ENVIRONMENT_TEST

    /**
     * The allowed networks to be requested from the API. If the user has cards from networks not
     * specified here in their account, these will not be offered for them to choose in the popup.
     *
     * @value #SUPPORTED_NETWORKS
     */
    val SUPPORTED_NETWORKS = listOf(
            "AMEX",
            "DISCOVER",
            "JCB",
            "MASTERCARD",
            "VISA")

    /**
     * The Google Pay API may return cards on file on Google.com (PAN_ONLY) and/or a device token on
     * an Android device authenticated with a 3-D Secure cryptogram (CRYPTOGRAM_3DS).
     *
     * @value #SUPPORTED_METHODS
     */
    val SUPPORTED_METHODS = listOf(
            "PAN_ONLY",
            "CRYPTOGRAM_3DS")

    /**
     * Required by the API, but not visible to the user.
     *
     * @value #COUNTRY_CODE Your local country
     */
    const val COUNTRY_CODE = "US"

    /**
     * Required by the API, but not visible to the user.
     *
     * @value #CURRENCY_CODE Your local currency
     */
    const val CURRENCY_CODE = "USD"

    /**
     * Supported countries for shipping (use ISO 3166-1 alpha-2 country codes). Relevant only when
     * requesting a shipping address.
     *
     * @value #SHIPPING_SUPPORTED_COUNTRIES
     */
    val SHIPPING_SUPPORTED_COUNTRIES = listOf("US", "GB")

    /**
     * The name of your payment processor/gateway. Please refer to their documentation for more
     * information.
     *
     * @value #PAYMENT_GATEWAY_TOKENIZATION_NAME
     */
    private const val PAYMENT_GATEWAY_TOKENIZATION_NAME = "example"

    /**
     * Custom parameters required by the processor/gateway.
     * In many cases, your processor / gateway will only require a gatewayMerchantId.
     * Please refer to your processor's documentation for more information. The number of parameters
     * required and their names vary depending on the processor.
     *
     * @value #PAYMENT_GATEWAY_TOKENIZATION_PARAMETERS
     */
    val PAYMENT_GATEWAY_TOKENIZATION_PARAMETERS = mapOf(
            "gateway" to PAYMENT_GATEWAY_TOKENIZATION_NAME,
            "gatewayMerchantId" to "exampleGatewayMerchantId"
    )

    /**
     * Only used for `DIRECT` tokenization. Can be removed when using `PAYMENT_GATEWAY`
     * tokenization.
     *
     * @value #DIRECT_TOKENIZATION_PUBLIC_KEY
     */
    const val DIRECT_TOKENIZATION_PUBLIC_KEY = "REPLACE_ME"

    /**
     * Parameters required for `DIRECT` tokenization.
     * Only used for `DIRECT` tokenization. Can be removed when using `PAYMENT_GATEWAY`
     * tokenization.
     *
     * @value #DIRECT_TOKENIZATION_PARAMETERS
     */
    val DIRECT_TOKENIZATION_PARAMETERS = mapOf(
            "protocolVersion" to "ECv1",
            "publicKey" to DIRECT_TOKENIZATION_PUBLIC_KEY
    )
}

Constants.kt

Java

ActivitySuccess activityUtilView modelConstants
/*
 * Copyright 2024 Google Inc.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package com.google.android.gms.samples.pay.activity;

import android.app.Activity;
import android.content.Intent;
import android.os.Bundle;
import android.util.Log;
import android.view.View;
import android.widget.Toast;

import androidx.activity.result.ActivityResultLauncher;
import androidx.annotation.Nullable;
import androidx.appcompat.app.AppCompatActivity;
import androidx.lifecycle.ViewModelProvider;

import com.google.android.gms.common.api.CommonStatusCodes;
import com.google.android.gms.samples.pay.R;
import com.google.android.gms.samples.pay.databinding.ActivityCheckoutBinding;
import com.google.android.gms.samples.pay.util.PaymentsUtil;
import com.google.android.gms.samples.pay.viewmodel.CheckoutViewModel;
import com.google.android.gms.tasks.Task;
import com.google.android.gms.wallet.PaymentData;
import com.google.android.gms.wallet.button.ButtonOptions;
import com.google.android.gms.wallet.button.PayButton;
import com.google.android.gms.wallet.contract.TaskResultContracts.GetPaymentDataResult;

import org.json.JSONException;
import org.json.JSONObject;

import java.util.Locale;

/**
 * Checkout implementation for the app
 */
public class CheckoutActivity extends AppCompatActivity {

  private CheckoutViewModel model;

  private PayButton googlePayButton;

  private final ActivityResultLauncher<Task<PaymentData>> paymentDataLauncher =
      registerForActivityResult(new GetPaymentDataResult(), result -> {
        int statusCode = result.getStatus().getStatusCode();
        switch (statusCode) {
          case CommonStatusCodes.SUCCESS:
            handlePaymentSuccess(result.getResult());
            break;
          //case CommonStatusCodes.CANCELED: The user canceled
          case CommonStatusCodes.DEVELOPER_ERROR:
            handleError(statusCode, result.getStatus().getStatusMessage());
            break;
          default:
            handleError(statusCode, "Unexpected non API" +
                " exception when trying to deliver the task result to an activity!");
            break;
        }
      });

  /**
   * Initialize the Google Pay API on creation of the activity
   *
   * @see Activity#onCreate(android.os.Bundle)
   */
  @Override
  protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    initializeUi();

    // Check Google Pay availability
    model = new ViewModelProvider(this).get(CheckoutViewModel.class);
    model.canUseGooglePay.observe(this, this::setGooglePayAvailable);
  }

  private void initializeUi() {

    // Use view binding to access the UI elements
    ActivityCheckoutBinding layoutBinding = ActivityCheckoutBinding.inflate(getLayoutInflater());
    setContentView(layoutBinding.getRoot());

    // The Google Pay button is a layout file – take the root view
    googlePayButton = layoutBinding.googlePayButton;
    try {
      googlePayButton.initialize(
          ButtonOptions.newBuilder()
              .setAllowedPaymentMethods(PaymentsUtil.getAllowedPaymentMethods().toString()).build()
      );
      googlePayButton.setOnClickListener(this::requestPayment);
    } catch (JSONException e) {
      // Keep Google Pay button hidden (consider logging this to your app analytics service)
    }
  }

  /**
   * If isReadyToPay returned {@code true}, show the button and hide the "checking" text.
   * Otherwise, notify the user that Google Pay is not available. Please adjust to fit in with
   * your current user flow. You are not required to explicitly let the user know if isReadyToPay
   * returns {@code false}.
   *
   * @param available isReadyToPay API response.
   */
  private void setGooglePayAvailable(boolean available) {
    if (available) {
      googlePayButton.setVisibility(View.VISIBLE);
    } else {
      Toast.makeText(this, R.string.google_pay_status_unavailable, Toast.LENGTH_LONG).show();
    }
  }

  public void requestPayment(View view) {
    // The price provided to the API should include taxes and shipping.
    final Task<PaymentData> task = model.getLoadPaymentDataTask("50.2");
    task.addOnCompleteListener(paymentDataLauncher::launch);
  }

  /**
   * PaymentData response object contains the payment information, as well as any additional
   * requested information, such as billing and shipping address.
   *
   * @param paymentData A response object returned by Google after a payer approves payment.
   * @see <a href="https://developers.google.com/pay/api/android/reference/
   * object#PaymentData">PaymentData</a>
   */
  private void handlePaymentSuccess(PaymentData paymentData) {
    final String paymentInfo = paymentData.toJson();

    try {
      JSONObject paymentMethodData = new JSONObject(paymentInfo).getJSONObject("paymentMethodData");
      // If the gateway is set to "example", no payment information is returned - instead, the
      // token will only consist of "examplePaymentMethodToken".

      final JSONObject info = paymentMethodData.getJSONObject("info");
      final String billingName = info.getJSONObject("billingAddress").getString("name");
      Toast.makeText(
          this, getString(R.string.payments_show_name, billingName),
          Toast.LENGTH_LONG).show();

      // Logging token string.
      Log.d("Google Pay token", paymentMethodData
          .getJSONObject("tokenizationData")
          .getString("token"));

      startActivity(new Intent(this, CheckoutSuccessActivity.class));

    } catch (JSONException e) {
      Log.e("handlePaymentSuccess", "Error: " + e);
    }
  }

  /**
   * At this stage, the user has already seen a popup informing them an error occurred. Normally,
   * only logging is required.
   *
   * @param statusCode holds the value of any constant from CommonStatusCode or one of the
   *                   WalletConstants.ERROR_CODE_* constants.
   * @see <a href="https://developers.google.com/android/reference/com/google/android/gms/wallet/
   * WalletConstants#constant-summary">Wallet Constants Library</a>
   */
  private void handleError(int statusCode, @Nullable String message) {
    Log.e("loadPaymentData failed",
        String.format(Locale.getDefault(), "Error code: %d, Message: %s", statusCode, message));
  }
}

CheckoutActivity.java

    
/*
 * Copyright 2024 Google Inc.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package com.google.android.gms.samples.pay.activity;

import android.os.Bundle;

import androidx.appcompat.app.AppCompatActivity;

import com.google.android.gms.samples.pay.databinding.ActivityCheckoutSuccessBinding;

public class CheckoutSuccessActivity extends AppCompatActivity {

  @Override
  protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);

    ActivityCheckoutSuccessBinding layoutBinding = ActivityCheckoutSuccessBinding.inflate(getLayoutInflater());
    setContentView(layoutBinding.getRoot());
  }
}
CheckoutSuccessActivity.java

    
/*
 * Copyright 2024 Google Inc.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package com.google.android.gms.samples.pay.util;

import android.content.Context;

import com.google.android.gms.samples.pay.Constants;
import com.google.android.gms.wallet.PaymentsClient;
import com.google.android.gms.wallet.Wallet;

import org.json.JSONArray;
import org.json.JSONException;
import org.json.JSONObject;

import java.math.BigDecimal;
import java.math.BigInteger;
import java.math.RoundingMode;

/**
 * Contains helper static methods for dealing with the Payments API.
 *
 * <p>Many of the parameters used in the code are optional and are set here merely to call out their
 * existence. Please consult the documentation to learn more and feel free to remove ones not
 * relevant to your implementation.
 */
public class PaymentsUtil {

  /**
   * Create a Google Pay API base request object with properties used in all requests.
   *
   * @return Google Pay API base request object.
   * @throws JSONException if the object is malformed.
   */
  private static JSONObject getBaseRequest() throws JSONException {
    return new JSONObject()
        .put("apiVersion", 2)
        .put("apiVersionMinor", 0);
  }

  /**
   * Creates an instance of {@link PaymentsClient} for use in an {@link Context} using the
   * environment and theme set in {@link Constants}.
   *
   * @param context is the caller's context.
   */
  public static PaymentsClient createPaymentsClient(Context context) {
    Wallet.WalletOptions walletOptions =
        new Wallet.WalletOptions.Builder().setEnvironment(Constants.PAYMENTS_ENVIRONMENT).build();
    return Wallet.getPaymentsClient(context, walletOptions);
  }

  /**
   * Gateway Integration: Identify your gateway and your app's gateway merchant identifier.
   *
   * <p>The Google Pay API response will return an encrypted payment method capable of being charged
   * by a supported gateway after payer authorization.
   *
   * <p>TODO: Check with your gateway on the parameters to pass and modify them in Constants.java.
   *
   * @return Payment data tokenization for the CARD payment method.
   * @throws JSONException if the object is malformed.
   * @see <a href=
   * "https://developers.google.com/pay/api/android/reference/object#PaymentMethodTokenizationSpecification">PaymentMethodTokenizationSpecification</a>
   */
  private static JSONObject getGatewayTokenizationSpecification() throws JSONException {
    return new JSONObject()
        .put("type", "PAYMENT_GATEWAY")
        .put("parameters", new JSONObject()
            .put("gateway", "example")
            .put("gatewayMerchantId", "exampleGatewayMerchantId")
        );
  }

  /**
   * {@code DIRECT} Integration: Decrypt a response directly on your servers. This configuration has
   * additional data security requirements from Google and additional PCI DSS compliance complexity.
   *
   * <p>Please refer to the documentation for more information about {@code DIRECT} integration. The
   * type of integration you use depends on your payment processor.
   *
   * @return Payment data tokenization for the CARD payment method.
   * @throws JSONException if the object is malformed.
   * @see <a
   * href="https://developers.google.com/pay/api/android/reference/object#PaymentMethodTokenizationSpecification">PaymentMethodTokenizationSpecification</a>
   */
  private static JSONObject getDirectTokenizationSpecification()
      throws JSONException, RuntimeException {
    return new JSONObject()
        .put("type", "DIRECT")
        .put("parameters", new JSONObject(Constants.DIRECT_TOKENIZATION_PARAMETERS));
  }

  /**
   * Card networks supported by your app and your gateway.
   *
   * <p>TODO: Confirm card networks supported by your app and gateway & update in Constants.java.
   *
   * @return Allowed card networks
   * @see <a
   * href="https://developers.google.com/pay/api/android/reference/object#CardParameters">CardParameters</a>
   */
  private static JSONArray getAllowedCardNetworks() {
    return new JSONArray(Constants.SUPPORTED_NETWORKS);
  }

  /**
   * Card authentication methods supported by your app and your gateway.
   *
   * <p>TODO: Confirm your processor supports Android device tokens on your supported card networks
   * and make updates in Constants.java.
   *
   * @return Allowed card authentication methods.
   * @see <a
   * href="https://developers.google.com/pay/api/android/reference/object#CardParameters">CardParameters</a>
   */
  private static JSONArray getAllowedCardAuthMethods() {
    return new JSONArray(Constants.SUPPORTED_METHODS);
  }

  /**
   * Describe your app's support for the CARD payment method.
   *
   * <p>The provided properties are applicable to both an IsReadyToPayRequest and a
   * PaymentDataRequest.
   *
   * @return A CARD PaymentMethod object describing accepted cards.
   * @throws JSONException if the object is malformed.
   * @see <a
   * href="https://developers.google.com/pay/api/android/reference/object#PaymentMethod">PaymentMethod</a>
   */
  private static JSONObject getBaseCardPaymentMethod() throws JSONException {
    return new JSONObject()
        .put("type", "CARD")
        .put("parameters", new JSONObject()
            .put("allowedAuthMethods", getAllowedCardAuthMethods())
            .put("allowedCardNetworks", getAllowedCardNetworks())
            .put("billingAddressRequired", true)
            .put("billingAddressParameters", new JSONObject()
                .put("format", "FULL")
            )
        );
  }

  /**
   * Describe the expected returned payment data for the CARD payment method
   *
   * @return A CARD PaymentMethod describing accepted cards and optional fields.
   * @throws JSONException if the object is malformed.
   * @see <a
   * href="https://developers.google.com/pay/api/android/reference/object#PaymentMethod">PaymentMethod</a>
   */
  private static JSONObject getCardPaymentMethod() throws JSONException {
    return getBaseCardPaymentMethod()
        .put("tokenizationSpecification", getGatewayTokenizationSpecification());
  }

  /**
   * Return a collection of payment methods allowed to complete the operation with Google Pay.
   *
   * @return A JSONArray object with the list of payment methods.
   * @throws JSONException if the JSON object is malformed.
   */
  public static JSONArray getAllowedPaymentMethods() throws JSONException {
    return new JSONArray().put(getCardPaymentMethod());
  }

  /**
   * An object describing accepted forms of payment by your app, used to determine a viewer's
   * readiness to pay.
   *
   * @return API version and payment methods supported by the app.
   * @see <a
   * href="https://developers.google.com/pay/api/android/reference/object#IsReadyToPayRequest">IsReadyToPayRequest</a>
   */
  public static JSONObject getIsReadyToPayRequest() {
    try {
      return getBaseRequest()
          .put("allowedPaymentMethods", new JSONArray().put(getBaseCardPaymentMethod()));
    } catch (JSONException e) {
      return null;
    }
  }

  /**
   * Provide Google Pay API with a payment amount, currency, and amount status.
   *
   * @return information about the requested payment.
   * @throws JSONException if the object is malformed.
   * @see <a
   * href="https://developers.google.com/pay/api/android/reference/object#TransactionInfo">TransactionInfo</a>
   */
  private static JSONObject getTransactionInfo(String price) throws JSONException {
    return new JSONObject()
        .put("totalPrice", price)
        .put("totalPriceStatus", "FINAL")
        .put("countryCode", Constants.COUNTRY_CODE)
        .put("currencyCode", Constants.CURRENCY_CODE)
        .put("checkoutOption", "COMPLETE_IMMEDIATE_PURCHASE");
  }

  /**
   * Information about the merchant requesting payment information
   *
   * @return Information about the merchant.
   * @throws JSONException if the object is malformed.
   * @see <a
   * href="https://developers.google.com/pay/api/android/reference/object#MerchantInfo">MerchantInfo</a>
   */
  private static JSONObject getMerchantInfo() throws JSONException {
    return new JSONObject().put("merchantName", "Example Merchant");
  }

  /**
   * An object describing information requested in a Google Pay payment sheet
   *
   * @return Payment data expected by your app.
   * @see <a
   * href="https://developers.google.com/pay/api/android/reference/object#PaymentDataRequest">PaymentDataRequest</a>
   */
  public static JSONObject getPaymentDataRequest(String priceLabel) {
    try {
      return PaymentsUtil.getBaseRequest()
          .put("allowedPaymentMethods", getAllowedPaymentMethods())
          .put("transactionInfo", getTransactionInfo(priceLabel))
          .put("merchantInfo", getMerchantInfo())
          .put("shippingAddressRequired", true)
          .put("shippingAddressParameters", new JSONObject()
              .put("phoneNumberRequired", false)
              .put("allowedCountryCodes", new JSONArray(Constants.SHIPPING_SUPPORTED_COUNTRIES))
          );

    } catch (JSONException e) {
      return null;
    }
  }
}

PaymentsUtil.java

    
/*
 * Copyright 2024 Google Inc.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package com.google.android.gms.samples.pay.viewmodel;

import android.app.Application;
import android.util.Log;

import androidx.annotation.NonNull;
import androidx.lifecycle.AndroidViewModel;
import androidx.lifecycle.LiveData;
import androidx.lifecycle.MutableLiveData;

import com.google.android.gms.samples.pay.util.PaymentsUtil;
import com.google.android.gms.tasks.Task;
import com.google.android.gms.wallet.IsReadyToPayRequest;
import com.google.android.gms.wallet.PaymentData;
import com.google.android.gms.wallet.PaymentDataRequest;
import com.google.android.gms.wallet.PaymentsClient;

import org.json.JSONObject;

public class CheckoutViewModel extends AndroidViewModel {

    // 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 priceLabel the price to show on the payment sheet.
     * @return a Task with the payment information.
     */
    public Task<PaymentData> getLoadPaymentDataTask(String priceLabel) {
        JSONObject paymentDataRequestJson = PaymentsUtil.getPaymentDataRequest(priceLabel);
        if (paymentDataRequestJson == null) {
            return null;
        }

        PaymentDataRequest request =
                PaymentDataRequest.fromJson(paymentDataRequestJson.toString());
        return paymentsClient.loadPaymentData(request);
    }
}
CheckoutViewModel.java

    
/*
 * Copyright 2024 Google Inc.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package com.google.android.gms.samples.pay;

import com.google.android.gms.wallet.WalletConstants;

import java.util.Arrays;
import java.util.HashMap;
import java.util.List;

/**
 * This file contains several constants you must edit before proceeding.
 * Please take a look at PaymentsUtil.java to see where the constants are used and to potentially
 * remove ones not relevant to your integration.
 *
 * <p>Required changes:
 * <ol>
 * <li> Update SUPPORTED_NETWORKS and SUPPORTED_METHODS if required (consult your processor if
 *      unsure)
 * <li> Update CURRENCY_CODE to the currency you use.
 * <li> Update SHIPPING_SUPPORTED_COUNTRIES to list the countries where you currently ship. If this
 *      is not applicable to your app, remove the relevant bits from PaymentsUtil.java.
 * <li> If you're integrating with your {@code PAYMENT_GATEWAY}, update
 *      PAYMENT_GATEWAY_TOKENIZATION_NAME and PAYMENT_GATEWAY_TOKENIZATION_PARAMETERS per the
 *      instructions they provided. You don't need to update DIRECT_TOKENIZATION_PUBLIC_KEY.
 * <li> If you're using {@code DIRECT} integration, please edit protocol version and public key as
 *      per the instructions.
 */
public class Constants {

  /**
   * Changing this to ENVIRONMENT_PRODUCTION will make the API return chargeable card information.
   * Please refer to the documentation to read about the required steps needed to enable
   * ENVIRONMENT_PRODUCTION.
   *
   * @value #PAYMENTS_ENVIRONMENT
   */
  public static final int PAYMENTS_ENVIRONMENT = WalletConstants.ENVIRONMENT_TEST;

  /**
   * The allowed networks to be requested from the API. If the user has cards from networks not
   * specified here in their account, these will not be offered for them to choose in the popup.
   *
   * @value #SUPPORTED_NETWORKS
   */
  public static final List<String> SUPPORTED_NETWORKS = Arrays.asList(
      "AMEX",
      "DISCOVER",
      "JCB",
      "MASTERCARD",
      "VISA");

  /**
   * The Google Pay API may return cards on file on Google.com (PAN_ONLY) and/or a device token on
   * an Android device authenticated with a 3-D Secure cryptogram (CRYPTOGRAM_3DS).
   *
   * @value #SUPPORTED_METHODS
   */
  public static final List<String> SUPPORTED_METHODS = Arrays.asList(
      "PAN_ONLY",
      "CRYPTOGRAM_3DS");

  /**
   * Required by the API, but not visible to the user.
   *
   * @value #COUNTRY_CODE Your local country
   */
  public static final String COUNTRY_CODE = "US";

  /**
   * Required by the API, but not visible to the user.
   *
   * @value #CURRENCY_CODE Your local currency
   */
  public static final String CURRENCY_CODE = "USD";

  /**
   * Supported countries for shipping (use ISO 3166-1 alpha-2 country codes). Relevant only when
   * requesting a shipping address.
   *
   * @value #SHIPPING_SUPPORTED_COUNTRIES
   */
  public static final List<String> SHIPPING_SUPPORTED_COUNTRIES = Arrays.asList("US", "GB");

  /**
   * The name of your payment processor/gateway. Please refer to their documentation for more
   * information.
   *
   * @value #PAYMENT_GATEWAY_TOKENIZATION_NAME
   */
  public static final String PAYMENT_GATEWAY_TOKENIZATION_NAME = "example";

  /**
   * Custom parameters required by the processor/gateway.
   * In many cases, your processor / gateway will only require a gatewayMerchantId.
   * Please refer to your processor's documentation for more information. The number of parameters
   * required and their names vary depending on the processor.
   *
   * @value #PAYMENT_GATEWAY_TOKENIZATION_PARAMETERS
   */
  public static final HashMap<String, String> PAYMENT_GATEWAY_TOKENIZATION_PARAMETERS =
      new HashMap<String, String>() {{
        put("gateway", PAYMENT_GATEWAY_TOKENIZATION_NAME);
        put("gatewayMerchantId", "exampleGatewayMerchantId");
        // Your processor may require additional parameters.
      }};

  /**
   * Only used for {@code DIRECT} tokenization. Can be removed when using {@code PAYMENT_GATEWAY}
   * tokenization.
   *
   * @value #DIRECT_TOKENIZATION_PUBLIC_KEY
   */
  public static final String DIRECT_TOKENIZATION_PUBLIC_KEY = "REPLACE_ME";

  /**
   * Parameters required for {@code DIRECT} tokenization.
   * Only used for {@code DIRECT} tokenization. Can be removed when using {@code PAYMENT_GATEWAY}
   * tokenization.
   *
   * @value #DIRECT_TOKENIZATION_PARAMETERS
   */
  public static final HashMap<String, String> DIRECT_TOKENIZATION_PARAMETERS =
      new HashMap<String, String>() {{
        put("protocolVersion", "ECv2");
        put("publicKey", DIRECT_TOKENIZATION_PUBLIC_KEY);
      }};
}

Constants.java