Util class for implementing In App Subscription

SubscriptionUtil.class

import android.app.Activity;
import android.content.Context;
import android.util.Log;

import com.tcm.android.utils.purchaseUtils.IabHelper;
import com.tcm.android.utils.purchaseUtils.IabResult;
import com.tcm.android.utils.purchaseUtils.Inventory;
import com.tcm.android.utils.purchaseUtils.Purchase;
import com.tcm.android.utils.purchaseUtils.SkuDetails;

import java.util.ArrayList;

/**
 * Created by hrskrs on 5/5/2016.
 */
public class SubscriptionUtil {
  private static final int REQUEST_CODE = 10001;
  private static final String base64EncodedPublicKey = "YOUR_PUBLIC_KEY";

  private IabHelper iabHelper;
  private Context context;

  private SubscriptionUtil() {
    //No instance
  }

  public SubscriptionUtil(Context context) {
    this.context = context;
    iabHelper = new IabHelper(context, base64EncodedPublicKey);
    iabHelper.enableDebugLogging(true, "TEST");
    setup();
  }

  private void setup() {
    if (iabHelper != null) {
      iabHelper.startSetup(new IabHelper.OnIabSetupFinishedListener() {
        @Override
        public void onIabSetupFinished(IabResult result) {
          if (result.isFailure()) {
            Log.d("TEST", "Problem setting up In-app Billing: " + result);
            dispose();
          }
        }
      });
    }
  }

  public void initSubscription(final String subscriptionType,
                               SubscriptionFinishedListener subscriptionFinishedListener) {
    initSubscriptionWithExtras(subscriptionType, subscriptionFinishedListener, "");
  }

  public void initSubscriptionWithExtras(final String subscriptionType,
                                         final SubscriptionFinishedListener subscriptionFinishedListener,
                                         String payload) {
    if (iabHelper != null) {
      try {
        iabHelper.launchSubscriptionPurchaseFlow((Activity) context,
            subscriptionType,
            REQUEST_CODE,
            new IabHelper.OnIabPurchaseFinishedListener() {
              @Override
              public void onIabPurchaseFinished(IabResult result, Purchase info) {
                if (result.isFailure()) {
                  Log.e("TEST", "Error purchasing: " + result);
                  return;
                }
                if (info.getSku().equals(subscriptionType)) {
                  if(subscriptionFinishedListener != null){
                    subscriptionFinishedListener.onSuccess();
                  }
                  Log.e("TEST", "Thank you for upgrading to premium!");
                }
              }
            },
            payload
        );
      } catch (IabHelper.IabAsyncInProgressException e) {
        e.printStackTrace();
      }
      //In case you get below error:
      //`Can't start async operation (refresh inventory) because another async operation (launchPurchaseFlow) is in progress.`
      //Include this line of code to end proccess after purchase
      //iabHelper.flagEndAsync();
    }
  }

  public void getSkuDetailsList(
      final ArrayList<String> skuIdsList,
      final SubscriptionInventoryListener subscriptionInventoryListener
  ) {
    if (iabHelper != null) {
      try {
        iabHelper.queryInventoryAsync(true, null, skuIdsList, new IabHelper.QueryInventoryFinishedListener() {
          @Override
          public void onQueryInventoryFinished(IabResult result, Inventory inventory) {
            if (result.isFailure()) {
              Log.d("TEST", "Problem querying inventory: " + result);
              dispose();
              return;
            }
            ArrayList<SkuDetails> skuDetailsList = new ArrayList<>();
            for (String skuId : skuIdsList) {
              SkuDetails sku = inventory.getSkuDetails(skuId);
              if (sku.getSku().equals(skuId)) {
                skuDetailsList.add(sku);
                sku.getPrice();
              }
            }

            if (subscriptionInventoryListener != null) {
              subscriptionInventoryListener.onQueryInventoryFinished(skuDetailsList);
            }
          }
        });
      } catch (IabHelper.IabAsyncInProgressException e) {
        Log.e("TEST", "EXCEPTION:" + e.getMessage());
      }
    }

  }

  public void dispose() {
    if (iabHelper != null) {
      try {
        iabHelper.dispose();
      } catch (IabHelper.IabAsyncInProgressException e) {
        e.printStackTrace();
      }
      iabHelper = null;
    }
  }

  public IabHelper getIabHelper() {
    if (iabHelper == null) {
      iabHelper = new IabHelper(context, base64EncodedPublicKey);
    }
    return iabHelper;
  }

  public interface SubscriptionInventoryListener {
    void onQueryInventoryFinished(ArrayList<SkuDetails> skuList);
  }

  public interface SubscriptionFinishedListener{
    void onSuccess();
  }
}