Welcome to in-app-purchase - Buy coins (Android Studio Java*)

Consumable Item In-App Purchases: https://github.com/wdtheprovider/in-app-purchase

In this repository i'm going to show you how to integrate In-App Purchases of Google Play Billing version 5+ in 8 steps. I follow the officailly google docs, i'm not using any third-party library

Pre-requisite

• Google Play Console Account
• Published App on Play Store
• Tester Device with GMS

YouTube Video: Part-1 | Intro Demo: https://youtu.be/nQrsVB7quKw

YouTube Video: Part-2 | Configure Testing Device: https://youtu.be/j6wWVMj-fi8

YouTube Video: Part-3 | Integrating The Methods to purchase the products: https://www.youtube.com/watch?v=7cf8yHdXMdA

Configure Your Testing device by adding the gmail account to internal testing testers 
and License testing (Watch the YouTube video for clarity: https://youtu.be/j6wWVMj-fi8 )

Troubleshooting

- If Products are not shown on the button, Please check if you configured your testing device with the right gmail you have in Internal Testing and Licence Testing.

The following methods (These are the methods you need for the IAP System to work, you can copy and paste)

void establishConnection(){}
void showProducts(){}
void launchPurchaseFlow(){}
void verifySubPayment(Purchase purchases){}
void checkSubscription(){}
void giveUserCoins (){}

Step 1: Add the Google Play Billing Library dependency

Step 2: Initialize a BillingClient with PurchasesUpdatedListener

Step 3: Establish a connection to Google Play

Step 4: Show products available to buy

Step 5: Launch the purchase flow

Step 6: Processing purchases / Verify Payment

Step 7: Handling pending transactions

**Step 8: Give user coins **

Learn More: https://developer.android.com/google/play/billing/integrate

Step 1: Add the Google Play Billing Library dependency

//Add the Google Play Billing Library dependency to your app's build.gradle file as shown:

dependencies {

    def billing_version = "5.0.0"
    implementation "com.android.billingclient:billing:$billing_version"
    implementation 'com.google.guava:listenablefuture:9999.0-empty-to-avoid-conflict-with-guava'
    implementation 'com.google.guava:guava:24.1-jre'
    
}

//And Open Manifest File and add this permission
<uses-permission android:name="com.android.vending.BILLING" />

Step 2: Initialize a BillingClient with PurchasesUpdatedListener

..... 
  //Initialize a BillingClient with PurchasesUpdatedListener onCreate method

    BillingClient billingClient;
    TextView clicks;
    Button btn_5;
    Prefs prefs ;
    List<ProductDetails> productDetailsList;
    Activity activity;
    String TAG = "TestInApp";
    Handler handler;
    ProgressBar progress_circular;
    List<String> productIds;
    List<Integer> coins;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_selling);

        clicks = findViewById(R.id.clicks);
        btn_5 = findViewById(R.id.btn_10);
        progress_circular = findViewById(R.id.progress_circular);

        prefs = new Prefs(this);
        handler = new Handler();

        productIds = new ArrayList<>();
        coins = new ArrayList<>();
        productDetailsList = new ArrayList<>();

        productIds.add("10_coins_id");
        coins.add(10); 
        
        activity = this;

        billingClient = BillingClient.newBuilder(this)
                .enablePendingPurchases()
                .setListener(
                        (billingResult, list) -> {
                            if(billingResult.getResponseCode()==BillingClient.BillingResponseCode.OK && list != null) {
                                for (Purchase purchase: list){
                                    verifyPurchase(purchase);
                                }
                            }
                        }
                ).build();

        //start the connection after initializing the billing client
        connectGooglePlayBilling();

        btn_5.setOnClickListener(v -> {
            //we are opening product at index zero since we only have one product
            launchPurchaseFlow(productDetailsList.get(0));
        });
    }
                

Step 3: Establish a connection to Google Play

 
    void connectGooglePlayBilling() {
        billingClient.startConnection(new BillingClientStateListener() {
            @Override
            public void onBillingServiceDisconnected() {
                connectGooglePlayBilling();
            }

            @Override
            public void onBillingSetupFinished(@NonNull BillingResult billingResult) {
                if (billingResult.getResponseCode() == BillingClient.BillingResponseCode.OK) {
                    showProducts();
                }
            }
        });

    }
    

Step 4: Show products available to buy

@SuppressLint("SetTextI18n")

    void showProducts() {
    
        ImmutableList<QueryProductDetailsParams.Product> productList = ImmutableList.of(
                //Product 1
                QueryProductDetailsParams.Product.newBuilder()
                        .setProductId("test_coins_111")
                        .setProductType(BillingClient.ProductType.INAPP)
                        .build()
        );

        QueryProductDetailsParams params = QueryProductDetailsParams.newBuilder()
                .setProductList(productList)
                .build();

        billingClient.queryProductDetailsAsync(params, (billingResult, list) -> {
            //Clear the list
            productDetailsList.clear();

            Log.d(TAG,"Size "+list.size());

            //Handler to delay by two seconds to wait for google play to return the list of products.
            handler.postDelayed(() -> {
                //Adding new productList, returned from google play
                productDetailsList.addAll(list);

                //Since we have one product, we use index zero (0) from list
                ProductDetails productDetails = list.get(0);

                //Getting product details
                String price = productDetails.getOneTimePurchaseOfferDetails().getFormattedPrice();
                String productName = productDetails.getName();

                //Updating the UI
                //If the product is not showing then it means that you didn't properly setup your Testing email.
                btn_5.setText(price +"  -  "+productName);

                //Showing the button.
                btn_5.setVisibility(View.VISIBLE);
                progress_circular.setVisibility(View.INVISIBLE);

                }, 2000);
        });
    }
    

Step 5: Launch the purchase flow

  
     void launchPurchaseFlow(ProductDetails productDetails) {
        ImmutableList<BillingFlowParams.ProductDetailsParams> productDetailsParamsList =
                ImmutableList.of(
                        BillingFlowParams.ProductDetailsParams.newBuilder()
                                .setProductDetails(productDetails)
                                .build()
                );
        BillingFlowParams billingFlowParams = BillingFlowParams.newBuilder()
                .setProductDetailsParamsList(productDetailsParamsList)
                .build();
        billingClient.launchBillingFlow(activity, billingFlowParams);
    }

Step 6: Processing purchases / Verify Payment

  void verifyPurchase(Purchase purchase) {
        ConsumeParams consumeParams = ConsumeParams.newBuilder()
                .setPurchaseToken(purchase.getPurchaseToken())
                .build();
        ConsumeResponseListener listener = (billingResult, s) -> {
            if (billingResult.getResponseCode() == BillingClient.BillingResponseCode.OK) {
                giveUserCoins(purchase);
            }
        };

        billingClient.consumeAsync(consumeParams, listener);
    }
    

Step 7: Handling pending transactions

   
    protected void onResume() {
        super.onResume();
        billingClient.queryPurchasesAsync(
                QueryPurchasesParams.newBuilder().setProductType(BillingClient.ProductType.INAPP).build(),
                (billingResult, list) -> {
                    if (billingResult.getResponseCode() == BillingClient.BillingResponseCode.OK) {
                        for (Purchase purchase : list) {
                            if (purchase.getPurchaseState() == Purchase.PurchaseState.PURCHASED && !purchase.isAcknowledged()) {
                                verifyPurchase(purchase);
                            }
                        }
                    }
                }
        );
    }
    

Step 8: Give user coins

SuppressLint("SetTextI18n")
    void giveUserCoins(Purchase purchase) {
        //set coins
        prefs.setInt("coins",(coins.get(0) * purchase.getQuantity()) + prefs.getInt("coins",0));
        //Update UI
        clicks.setText("You have "+prefs.getInt("coins",0)+ " coins(s)");
    }