Payments Module for Native Android

private PurchasesUpdatedListener purchasesUpdatedListener = new PurchasesUpdatedListener() {
    @Override
    public void onPurchasesUpdated(int billingResult, List<Purchase> purchases) {
         if (billingResult == BillingResponse.OK) {
             if (purchases == null) {
                 return;
             }
             for (Purchase purchase: purchases) {
                 String payload = purchase.getDeveloperPayload(); // get developer payload
                 // handle successful purchase here
             }
         } else if (billingResult == BillingResponse.USER_CANCELED) {
            Log.i(TAG, "onPurchasesUpdated() - user cancelled the purchase flow - skipping");
         } else {
            Log.w(TAG, "onPurchasesUpdated() got unknown billingResult: " + billingResult);
         }
    }
 };

 private BillingClient billingClient = BillingClient.newBuilder(activity)
    .setListener(purchasesUpdatedListener)
    .setAppId(PAYMENT_ID)
    .build();

private val purchasesUpdatedListener = object : PurchasesUpdatedListener {
    override fun onPurchasesUpdated(billingResult: Int, purchases: List<Purchase>?) {
        if (billingResult == BillingResponse.OK) {
            if (purchases == null) {
                return
            }
            for (purchase in purchases) {
                val payload = purchase.developerPayload // get developer payload
                // handle successful purchase here
            }
        } else if (billingResult == BillingResponse.USER_CANCELED) {
            Log.i(TAG, "onPurchasesUpdated() - user cancelled the purchase flow - skipping")
        } else {
            Log.w(TAG, "onPurchasesUpdated() got unknown billingResult: $billingResult")
        }
    }
}

private val billingClient = BillingClient.newBuilder(activity)
    .setListener(purchasesUpdatedListener)
    .setAppId(PAYMENT_ID)
    .build()

billingClient.startConnection(new BillingClientStateListener() {
   @Override
   public void onBillingSetupFinished(int billingResult) {
     if (billingResult == 0) {
       // The BillingClient is ready. You can query purchases here. 
       QueryPurchasesParams params = QueryPurchasesParams.newBuilder().setProductType(BillingClient.SkuType.ALL).build();
       billingClient.queryPurchasesAsync(params, new PurchasesResponseListener() {
         @Override
         public void onQueryPurchasesResponse(BillingResult billingResult, List < Purchase > list) {
         // Allot the purchased item to the user and call consume/acknowledge.
         }
       });
     }
   }
   @Override
   public void onBillingServiceDisconnected() {
     // Try to restart the connection on the next request to 
     // Payments module by calling the startConnection() method. 
   }
 });

billingClient.startConnection(object : BillingClientStateListener {
     override fun onBillingSetupFinished(billingResult: Int) {
         if (billingResult == 0) {
             // The BillingClient is ready. You can query purchases here. 
             val params = QueryPurchasesParams.newBuilder().setProductType(BillingClient.SkuType.ALL).build()
             billingClient.queryPurchasesAsync(params, object : PurchasesResponseListener {
                 override fun onQueryPurchasesResponse(billingResult: BillingResult, list: List< Purchase >) {
                     // Allot the purchased item to the user and call consume/acknowledge.
                 }
             })
         }
     }

     override fun onBillingServiceDisconnected() {
         // Try to restart the connection on the next request to 
         // Payments module by calling the startConnection() method. 
     }
 })

List < String > skuList = new ArrayList < > ();
 skuList.add("premium_upgrade");
 skuList.add("gas");
 SkuDetailsParams.Builder params = SkuDetailsParams.newBuilder();
 params.setSkusList(skuList).setType(SkuType.ALL);
 billingClient.querySkuDetailsAsync(params.build(),
   new SkuDetailsResponseListener() {
     @Override
     public void onSkuDetailsResponse(int billingResult,
       List < SkuDetails > skuDetailsList) {
       // Process the result.
     }
   });

val skuList = mutableListOf<String>()
 skuList.add("premium_upgrade")
 skuList.add("gas")
 val params = SkuDetailsParams.newBuilder()
     .setSkusList(skuList)
     .setType(SkuType.ALL)
 billingClient.querySkuDetailsAsync(params.build(),
     object : SkuDetailsResponseListener {
         override fun onSkuDetailsResponse(billingResult: Int, skuDetailsList: List<SkuDetails>) {
             // Process the result.
         }
     })

// An activity reference for billing flow initiation 
 Activity activity = ...; 
      
 // Call querySkuDetailsAsync() to retrieve a value for 'skuDetails'. 
 BillingFlowParams billingFlowParams = BillingFlowParams.newBuilder() 
    .setSkuDetails(skuDetails) 
    .setDeveloperPayload("optional developer payload")
    .build(); 
 billingClient.launchBillingFlow(activity, billingFlowParams); 
      
     //Result

// An activity reference for billing flow initiation 
 val activity : Activity = ...; 
  
 // Call querySkuDetailsAsync() to retrive a value for 'skuDetails'. 
 val flowParams = BillingFlowParams.newBuilder() 
         .setSkuDetails(skuDetails) 
         .setDeveloperPayload("optional developer payload")
         .build() 
 billingClient.launchBillingFlow(activity, flowParams)
 //Result

@Override 
 void onPurchasesUpdated(int billingResult, List<Purchase> purchases) { 
     if (billingResult == 0 && purchases != null) { 
         for (Purchase purchase : purchases) { 
             String payload = purchase.getDeveloperPayload(); // Get Developer Payload
             handlePurchase(purchase); 
         } 
     } else if (billingResult == 1) { 
             // Error Handling - Caused due to user terminating the purchase flow 
     } else { 
             // Error Handling - Any other causes (based on error code) 
     } 
 }

override fun onPurchasesUpdated(billingResult: int, purchases: List<Purchase>?) { 
     if (billingResult == 0 && purchases != null) { 
         for (purchase in purchases) { 
                 val payload: String = purchase.developerPayload // Get Developer Payload
                 handlePurchase(purchase)
         } 
     } else if (billingResult == 1) { 
             // Error Handling - Caused due to the user terminating the purchase flow. 
     } else { 
             // Error Handling - Any other causes (based on error code) 
     } 
 }

QueryPurchasesParams params = QueryPurchasesParams.newBuilder().setProductType(BillingClient.SkuType.ALL).build();
 billingClient.queryPurchasesAsync(params, new PurchasesResponseListener() {
   @Override
   public void onQueryPurchasesResponse(BillingResult billingResult, List < Purchase > list) {
        // Allot the purchased item to the user and call consume/acknowledge
   }
 });

val params = QueryPurchasesParams.newBuilder()
    .setProductType(BillingClient.SkuType.ALL)
    .build()

billingClient.queryPurchasesAsync(params, object : PurchasesResponseListener {
    override fun onQueryPurchasesResponse(billingResult: BillingResult, list: List) {
       // Allot the purchased item to the user and call consume/acknowledge
    }
})