Ekalips/BillingProvider.java

## billing_BillingProvider.java
package com.noctua.billing;

import android.app.Activity;
import android.support.annotation.Nullable;

import com.android.billingclient.api.Purchase;

import java.util.List;

/**
 * Created by wldev on 8/28/17.
 */

public interface BillingProvider {
    void connect();

    void disconnect();

    void addCallbackListener(BillingProviderCallbacks callbackListener);

    void removeCallbackListener(BillingProviderCallbacks callbackListener);

    boolean launchItemPurchase(Activity activity, String skuId);

    boolean launchSubPurchase(Activity activity, String skuId, @Nullable String oldSku);

    List<Purchase> getMyPurchases();
}

## billing_BillingProviderCallbacks.java
package com.noctua.billing;

import com.android.billingclient.api.Purchase;

import java.util.List;

/**
 * Created by wldev on 8/28/17.
 */

public interface BillingProviderCallbacks {
    void onBillingServiceConnected();

    void onBillingServiceDisconnected();

    void onBillingServiceUnAvailable();

    void onError();

    void onBillingFlowError();

    void onUserCanceledPurchase();

    void onPurchasesListUpdated(List<Purchase> purchases);

    void onItemAlreadyOwned();
}

## billing_BillingProviderCallbacksAdapter.java
package com.noctua.billing;

import com.android.billingclient.api.Purchase;

import java.util.List;

/**
 * Created by wldev on 9/13/17.
 */

public abstract class BillingProviderCallbacksAdapter implements BillingProviderCallbacks {
    @Override
    public void onBillingServiceConnected() {

    }

    @Override
    public void onBillingServiceDisconnected() {

    }

    @Override
    public void onBillingServiceUnAvailable() {

    }

    @Override
    public void onError() {

    }

    @Override
    public void onBillingFlowError() {

    }

    @Override
    public void onUserCanceledPurchase() {

    }

    @Override
    public void onPurchasesListUpdated(List<Purchase> purchases) {

    }

    @Override
    public void onItemAlreadyOwned() {

    }
}

## billing_BillingProviderImpl.java
package com.noctua.billing;

import android.app.Activity;
import android.content.Context;
import android.os.Handler;
import android.os.Looper;
import android.support.annotation.NonNull;
import android.support.annotation.Nullable;
import android.support.annotation.UiThread;
import android.text.TextUtils;
import android.util.Log;

import com.android.billingclient.api.BillingClient;
import com.android.billingclient.api.BillingClientImpl;
import com.android.billingclient.api.BillingClientStateListener;
import com.android.billingclient.api.BillingFlowParams;
import com.android.billingclient.api.Purchase;
import com.android.billingclient.api.PurchasesUpdatedListener;
import com.noctua.common.FuncUtils;

import java.lang.ref.WeakReference;
import java.util.ArrayList;
import java.util.List;

/**
 * Created by wldev on 8/28/17.
 */

public class BillingProviderImpl implements BillingProvider, PurchasesUpdatedListener, BillingClientStateListener {

    private static final String TAG = BillingProviderImpl.class.getSimpleName();
    private BillingClient mBillingClient;
    private Handler uiHandler;

    private final Context appContext;

    private List<BillingProviderCallbacks> billingProviderCallbacks = new ArrayList<>();

    public BillingProviderImpl(Context context) {
        appContext = context;
        mBillingClient = new BillingClient.Builder(context).setListener(this).build();
        uiHandler = new Handler(Looper.getMainLooper());
    }


    @Override
    public void connect() {
        if (Looper.myLooper() == Looper.getMainLooper()) {
            connectOrCreate();
        } else {
            connectOnUI();
        }
    }

    @Override
    public void disconnect() {
        if (billingProviderCallbacks.isEmpty()) {
            if (Looper.myLooper() == Looper.getMainLooper()) {
                disconnectAndClear();
            } else {
                disconnectOnUI();
            }
        } else {
            Log.d(TAG, "You can't disconnect service while there is at least one listener");
        }
    }

    private void connectOrCreate() {
        Log.d(TAG, "connectOrCreate: " + (mBillingClient == null));
        if (mBillingClient == null) {
            mBillingClient = new BillingClientImpl.Builder(appContext).setListener(this).build();
        }
        mBillingClient.startConnection(this);
    }

    private void disconnectAndClear() {
        Log.d(TAG, "disconnectAndClear: " + (mBillingClient != null));
        if (mBillingClient != null) {
            mBillingClient.endConnection();
            mBillingClient = null;
        }
    }

    @Override
    public void addCallbackListener(BillingProviderCallbacks callbackListener) {
        billingProviderCallbacks.add(callbackListener);
    }

    @Override
    public void removeCallbackListener(BillingProviderCallbacks callbackListener) {
        billingProviderCallbacks.remove(callbackListener);
    }

    @Override
    public boolean launchItemPurchase(final Activity activity, final String skuId) {
        if (mBillingClient.isReady()) {
            if (Looper.myLooper() == Looper.getMainLooper()) {
                launchBillingFlow(activity, BillingClient.SkuType.INAPP, skuId, null);
            } else {
                launchItemPurchaseOnUI(activity, skuId);
            }
            return true;
        } else {
            return false;
        }
    }

    @Override
    public boolean launchSubPurchase(final Activity activity, final String skuId, @Nullable final String lastSubSku) {
        if (mBillingClient.isReady()) {
            if (Looper.myLooper() == Looper.getMainLooper()) {
                launchBillingFlow(activity, BillingClient.SkuType.SUBS, skuId, lastSubSku);
            } else {
                launchSubPurchaseOnUI(activity, skuId, lastSubSku);
            }
            return true;
        } else {
            return false;
        }
    }

    @Override
    public void onBillingSetupFinished(@BillingClient.BillingResponse int resultCode) {
        Log.d(TAG, "onBillingSetupFinished() called with: resultCode = [" + resultCode + "]");
        if (billingProviderCallbacks != null) {
            switch (resultCode) {
                case BillingClient.BillingResponse.OK: {
                    forEachApply(new FuncUtils.MyConsumer<BillingProviderCallbacks>() {
                        @Override
                        public void accept(BillingProviderCallbacks billingProviderCallbacks) {
                            billingProviderCallbacks.onBillingServiceConnected();
                        }
                    });
                    break;
                }
                default: {
                    notifyAllListenersAboutError(resultCode);
                    break;
                }
            }
        }
    }

    @Override
    public void onBillingServiceDisconnected() {
        forEachApply(new FuncUtils.MyConsumer<BillingProviderCallbacks>() {
            @Override
            public void accept(BillingProviderCallbacks billingProviderCallbacks) {
                billingProviderCallbacks.onBillingServiceDisconnected();
            }
        });
    }

    @Override
    public void onPurchasesUpdated(@BillingClient.BillingResponse int responseCode, List<Purchase> purchases) {
        Log.d(TAG, "onPurchasesUpdated() called with: responseCode = [" + responseCode + "], purchases = [" + purchases + "]");
        if (billingProviderCallbacks != null) {
            switch (responseCode) {
                case BillingClient.BillingResponse.OK: {
                    handlePurchases(purchases);
                    break;
                }
                default: {
                    notifyAllListenersAboutError(responseCode);
                    break;
                }
            }
        }
    }

    private void handlePurchases(@Nullable final List<Purchase> purchases) {
        forEachApply(new FuncUtils.MyConsumer<BillingProviderCallbacks>() {
            @Override
            public void accept(BillingProviderCallbacks billingProviderCallbacks) {
                billingProviderCallbacks.onPurchasesListUpdated(purchases);
            }
        });
    }


    private void launchItemPurchaseOnUI(final Activity activity, final String skuId) {
        final WeakReference<Activity> activityWeakReference = new WeakReference<>(activity);
        final WeakReference<String> skuIDWeakReference = new WeakReference<>(skuId);
        uiHandler.post(new Runnable() {
            @Override
            public void run() {
                if (activityWeakReference.get() != null && skuIDWeakReference.get() != null) {
                    launchBillingFlow(activityWeakReference.get(), BillingClient.SkuType.INAPP, skuId, null);
                }
            }
        });
    }

    private void launchSubPurchaseOnUI(Activity activity, final String skuId, @Nullable final String oldSku) {
        final WeakReference<Activity> activityWeakReference = new WeakReference<>(activity);
        final WeakReference<String> skuIDWeakReference = new WeakReference<>(skuId);
        uiHandler.post(new Runnable() {
            @Override
            public void run() {
                if (activityWeakReference.get() != null && skuIDWeakReference.get() != null) {
                    launchBillingFlow(activityWeakReference.get(), BillingClient.SkuType.SUBS, skuId, oldSku);
                }
            }
        });
    }

    @UiThread
    private void connectOnUI() {
        if (!mBillingClient.isReady()) {
            uiHandler.post(new Runnable() {
                @Override
                public void run() {
                    connectOrCreate();
                }
            });
        }
    }

    @UiThread
    private void disconnectOnUI() {
        if (mBillingClient.isReady()) {
            uiHandler.post(new Runnable() {
                @Override
                public void run() {
                    disconnectAndClear();
                }
            });
        }
    }

    private void forEachApply(@NonNull FuncUtils.MyConsumer<? super BillingProviderCallbacks> consumer) {
        for (int i = 0; i < billingProviderCallbacks.size(); i++) {
            consumer.accept(billingProviderCallbacks.get(i));
        }
    }

    @Override
    public List<Purchase> getMyPurchases() {
        List<Purchase> purchases = new ArrayList<>();
        if (mBillingClient != null && mBillingClient.isReady()) {
            Purchase.PurchasesResult inApps = mBillingClient.queryPurchases(BillingClient.SkuType.INAPP);
            if (inApps != null && inApps.getPurchasesList() != null) {
                purchases.addAll(inApps.getPurchasesList());
            }
            Purchase.PurchasesResult subs = mBillingClient.queryPurchases(BillingClient.SkuType.SUBS);
            if (subs != null && subs.getPurchasesList() != null) {
                purchases.addAll(subs.getPurchasesList());
            }
        }
        Log.d(TAG, "getMyPurchases() returned: " + purchases.size());
        return purchases;
    }

    private void launchBillingFlow(Activity activity, @BillingClient.SkuType String skuType, String sku, @Nullable String oldSku) {
        BillingFlowParams.Builder paramsBuilder = new BillingFlowParams.Builder().setSku(sku).setType(skuType);
        if (!TextUtils.isEmpty(oldSku)) {
            paramsBuilder.addOldSku(oldSku);
        }

        int response = mBillingClient.launchBillingFlow(activity, paramsBuilder.build());
        if (response != BillingClient.BillingResponse.OK) {
            notifyAllListenersAboutError(response);
        }
    }

    private void notifyAllListenersAboutError(@BillingClient.BillingResponse int billingResponse) {
        switch (billingResponse) {
            case BillingClient.BillingResponse.BILLING_UNAVAILABLE:
            case BillingClient.BillingResponse.SERVICE_UNAVAILABLE:
            case BillingClient.BillingResponse.DEVELOPER_ERROR: {
                forEachApply(new FuncUtils.MyConsumer<BillingProviderCallbacks>() {
                    @Override
                    public void accept(BillingProviderCallbacks billingProviderCallbacks) {
                        billingProviderCallbacks.onBillingServiceUnAvailable();
                    }
                });
            }
            case BillingClient.BillingResponse.SERVICE_DISCONNECTED: {
                forEachApply(new FuncUtils.MyConsumer<BillingProviderCallbacks>() {
                    @Override
                    public void accept(BillingProviderCallbacks billingProviderCallbacks) {
                        billingProviderCallbacks.onBillingServiceDisconnected();
                    }
                });
                break;
            }
            case BillingClient.BillingResponse.USER_CANCELED: {
                forEachApply(new FuncUtils.MyConsumer<BillingProviderCallbacks>() {
                    @Override
                    public void accept(BillingProviderCallbacks billingProviderCallbacks) {
                        billingProviderCallbacks.onUserCanceledPurchase();
                    }
                });
                break;
            }
            case BillingClient.BillingResponse.ERROR: {
                forEachApply(new FuncUtils.MyConsumer<BillingProviderCallbacks>() {
                    @Override
                    public void accept(BillingProviderCallbacks billingProviderCallbacks) {
                        billingProviderCallbacks.onError();
                    }
                });
                break;
            }
            case BillingClient.BillingResponse.ITEM_ALREADY_OWNED: {
                forEachApply(new FuncUtils.MyConsumer<BillingProviderCallbacks>() {
                    @Override
                    public void accept(BillingProviderCallbacks billingProviderCallbacks) {
                        billingProviderCallbacks.onItemAlreadyOwned();
                    }
                });
                break;
            }
        }
    }
}

## BillingProvider.java
package com.noctua.billing;

import android.app.Activity;
import android.support.annotation.Nullable;

import com.android.billingclient.api.Purchase;

import java.util.List;

/**
 * Created by wldev on 8/28/17.
 */

public interface BillingProvider {
    void connect();

    void disconnect();

    void addCallbackListener(BillingProviderCallbacks callbackListener);

    void removeCallbackListener(BillingProviderCallbacks callbackListener);

    boolean launchItemPurchase(Activity activity, String skuId);

    boolean launchSubPurchase(Activity activity, String skuId, @Nullable String oldSku);

    List<Purchase> getMyPurchases();
}

## BillingProviderCallbacks.java
package com.noctua.billing;

import com.android.billingclient.api.Purchase;

import java.util.List;

/**
 * Created by wldev on 8/28/17.
 */

public interface BillingProviderCallbacks {
    void onBillingServiceConnected();

    void onBillingServiceDisconnected();

    void onBillingServiceUnAvailable();

    void onError();

    void onBillingFlowError();

    void onUserCanceledPurchase();

    void onPurchasesListUpdated(List<Purchase> purchases);

    void onItemAlreadyOwned();
}

## BillingProviderCallbacksAdapter.java
package com.noctua.billing;

import com.android.billingclient.api.Purchase;

import java.util.List;

/**
 * Created by wldev on 9/13/17.
 */

public abstract class BillingProviderCallbacksAdapter implements BillingProviderCallbacks {
    @Override
    public void onBillingServiceConnected() {

    }

    @Override
    public void onBillingServiceDisconnected() {

    }

    @Override
    public void onBillingServiceUnAvailable() {

    }

    @Override
    public void onError() {

    }

    @Override
    public void onBillingFlowError() {

    }

    @Override
    public void onUserCanceledPurchase() {

    }

    @Override
    public void onPurchasesListUpdated(List<Purchase> purchases) {

    }

    @Override
    public void onItemAlreadyOwned() {

    }
}

## BillingProviderImpl.java
package com.noctua.billing;

import android.app.Activity;
import android.content.Context;
import android.os.Handler;
import android.os.Looper;
import android.support.annotation.NonNull;
import android.support.annotation.Nullable;
import android.support.annotation.UiThread;
import android.text.TextUtils;
import android.util.Log;

import com.android.billingclient.api.BillingClient;
import com.android.billingclient.api.BillingClientImpl;
import com.android.billingclient.api.BillingClientStateListener;
import com.android.billingclient.api.BillingFlowParams;
import com.android.billingclient.api.Purchase;
import com.android.billingclient.api.PurchasesUpdatedListener;
import com.noctua.common.FuncUtils;

import java.lang.ref.WeakReference;
import java.util.ArrayList;
import java.util.List;

/**
 * Created by wldev on 8/28/17.
 */

public class BillingProviderImpl implements BillingProvider, PurchasesUpdatedListener, BillingClientStateListener {

    private static final String TAG = BillingProviderImpl.class.getSimpleName();
    private BillingClient mBillingClient;
    private Handler uiHandler;

    private final Context appContext;

    private List<BillingProviderCallbacks> billingProviderCallbacks = new ArrayList<>();

    public BillingProviderImpl(Context context) {
        appContext = context;
        mBillingClient = new BillingClient.Builder(context).setListener(this).build();
        uiHandler = new Handler(Looper.getMainLooper());
    }


    @Override
    public void connect() {
        if (Looper.myLooper() == Looper.getMainLooper()) {
            connectOrCreate();
        } else {
            connectOnUI();
        }
    }

    @Override
    public void disconnect() {
        if (billingProviderCallbacks.isEmpty()) {
            if (Looper.myLooper() == Looper.getMainLooper()) {
                disconnectAndClear();
            } else {
                disconnectOnUI();
            }
        } else {
            Log.d(TAG, "You can't disconnect service while there is at least one listener");
        }
    }

    private void connectOrCreate() {
        Log.d(TAG, "connectOrCreate: " + (mBillingClient == null));
        if (mBillingClient == null) {
            mBillingClient = new BillingClientImpl.Builder(appContext).setListener(this).build();
        }
        mBillingClient.startConnection(this);
    }

    private void disconnectAndClear() {
        Log.d(TAG, "disconnectAndClear: " + (mBillingClient != null));
        if (mBillingClient != null) {
            mBillingClient.endConnection();
            mBillingClient = null;
        }
    }

    @Override
    public void addCallbackListener(BillingProviderCallbacks callbackListener) {
        billingProviderCallbacks.add(callbackListener);
    }

    @Override
    public void removeCallbackListener(BillingProviderCallbacks callbackListener) {
        billingProviderCallbacks.remove(callbackListener);
    }

    @Override
    public boolean launchItemPurchase(final Activity activity, final String skuId) {
        if (mBillingClient.isReady()) {
            if (Looper.myLooper() == Looper.getMainLooper()) {
                launchBillingFlow(activity, BillingClient.SkuType.INAPP, skuId, null);
            } else {
                launchItemPurchaseOnUI(activity, skuId);
            }
            return true;
        } else {
            return false;
        }
    }

    @Override
    public boolean launchSubPurchase(final Activity activity, final String skuId, @Nullable final String lastSubSku) {
        if (mBillingClient.isReady()) {
            if (Looper.myLooper() == Looper.getMainLooper()) {
                launchBillingFlow(activity, BillingClient.SkuType.SUBS, skuId, lastSubSku);
            } else {
                launchSubPurchaseOnUI(activity, skuId, lastSubSku);
            }
            return true;
        } else {
            return false;
        }
    }

    @Override
    public void onBillingSetupFinished(@BillingClient.BillingResponse int resultCode) {
        Log.d(TAG, "onBillingSetupFinished() called with: resultCode = [" + resultCode + "]");
        if (billingProviderCallbacks != null) {
            switch (resultCode) {
                case BillingClient.BillingResponse.OK: {
                    forEachApply(new FuncUtils.MyConsumer<BillingProviderCallbacks>() {
                        @Override
                        public void accept(BillingProviderCallbacks billingProviderCallbacks) {
                            billingProviderCallbacks.onBillingServiceConnected();
                        }
                    });
                    break;
                }
                default: {
                    notifyAllListenersAboutError(resultCode);
                    break;
                }
            }
        }
    }

    @Override
    public void onBillingServiceDisconnected() {
        forEachApply(new FuncUtils.MyConsumer<BillingProviderCallbacks>() {
            @Override
            public void accept(BillingProviderCallbacks billingProviderCallbacks) {
                billingProviderCallbacks.onBillingServiceDisconnected();
            }
        });
    }

    @Override
    public void onPurchasesUpdated(@BillingClient.BillingResponse int responseCode, List<Purchase> purchases) {
        Log.d(TAG, "onPurchasesUpdated() called with: responseCode = [" + responseCode + "], purchases = [" + purchases + "]");
        if (billingProviderCallbacks != null) {
            switch (responseCode) {
                case BillingClient.BillingResponse.OK: {
                    handlePurchases(purchases);
                    break;
                }
                default: {
                    notifyAllListenersAboutError(responseCode);
                    break;
                }
            }
        }
    }

    private void handlePurchases(@Nullable final List<Purchase> purchases) {
        forEachApply(new FuncUtils.MyConsumer<BillingProviderCallbacks>() {
            @Override
            public void accept(BillingProviderCallbacks billingProviderCallbacks) {
                billingProviderCallbacks.onPurchasesListUpdated(purchases);
            }
        });
    }


    private void launchItemPurchaseOnUI(final Activity activity, final String skuId) {
        final WeakReference<Activity> activityWeakReference = new WeakReference<>(activity);
        final WeakReference<String> skuIDWeakReference = new WeakReference<>(skuId);
        uiHandler.post(new Runnable() {
            @Override
            public void run() {
                if (activityWeakReference.get() != null && skuIDWeakReference.get() != null) {
                    launchBillingFlow(activityWeakReference.get(), BillingClient.SkuType.INAPP, skuId, null);
                }
            }
        });
    }

    private void launchSubPurchaseOnUI(Activity activity, final String skuId, @Nullable final String oldSku) {
        final WeakReference<Activity> activityWeakReference = new WeakReference<>(activity);
        final WeakReference<String> skuIDWeakReference = new WeakReference<>(skuId);
        uiHandler.post(new Runnable() {
            @Override
            public void run() {
                if (activityWeakReference.get() != null && skuIDWeakReference.get() != null) {
                    launchBillingFlow(activityWeakReference.get(), BillingClient.SkuType.SUBS, skuId, oldSku);
                }
            }
        });
    }

    @UiThread
    private void connectOnUI() {
        if (!mBillingClient.isReady()) {
            uiHandler.post(new Runnable() {
                @Override
                public void run() {
                    connectOrCreate();
                }
            });
        }
    }

    @UiThread
    private void disconnectOnUI() {
        if (mBillingClient.isReady()) {
            uiHandler.post(new Runnable() {
                @Override
                public void run() {
                    disconnectAndClear();
                }
            });
        }
    }

    private void forEachApply(@NonNull FuncUtils.MyConsumer<? super BillingProviderCallbacks> consumer) {
        for (int i = 0; i < billingProviderCallbacks.size(); i++) {
            consumer.accept(billingProviderCallbacks.get(i));
        }
    }

    @Override
    public List<Purchase> getMyPurchases() {
        List<Purchase> purchases = new ArrayList<>();
        if (mBillingClient != null && mBillingClient.isReady()) {
            Purchase.PurchasesResult inApps = mBillingClient.queryPurchases(BillingClient.SkuType.INAPP);
            if (inApps != null && inApps.getPurchasesList() != null) {
                purchases.addAll(inApps.getPurchasesList());
            }
            Purchase.PurchasesResult subs = mBillingClient.queryPurchases(BillingClient.SkuType.SUBS);
            if (subs != null && subs.getPurchasesList() != null) {
                purchases.addAll(subs.getPurchasesList());
            }
        }
        Log.d(TAG, "getMyPurchases() returned: " + purchases.size());
        return purchases;
    }

    private void launchBillingFlow(Activity activity, @BillingClient.SkuType String skuType, String sku, @Nullable String oldSku) {
        BillingFlowParams.Builder paramsBuilder = new BillingFlowParams.Builder().setSku(sku).setType(skuType);
        if (!TextUtils.isEmpty(oldSku)) {
            paramsBuilder.addOldSku(oldSku);
        }

        int response = mBillingClient.launchBillingFlow(activity, paramsBuilder.build());
        if (response != BillingClient.BillingResponse.OK) {
            notifyAllListenersAboutError(response);
        }
    }

    private void notifyAllListenersAboutError(@BillingClient.BillingResponse int billingResponse) {
        switch (billingResponse) {
            case BillingClient.BillingResponse.BILLING_UNAVAILABLE:
            case BillingClient.BillingResponse.SERVICE_UNAVAILABLE:
            case BillingClient.BillingResponse.DEVELOPER_ERROR: {
                forEachApply(new FuncUtils.MyConsumer<BillingProviderCallbacks>() {
                    @Override
                    public void accept(BillingProviderCallbacks billingProviderCallbacks) {
                        billingProviderCallbacks.onBillingServiceUnAvailable();
                    }
                });
            }
            case BillingClient.BillingResponse.SERVICE_DISCONNECTED: {
                forEachApply(new FuncUtils.MyConsumer<BillingProviderCallbacks>() {
                    @Override
                    public void accept(BillingProviderCallbacks billingProviderCallbacks) {
                        billingProviderCallbacks.onBillingServiceDisconnected();
                    }
                });
                break;
            }
            case BillingClient.BillingResponse.USER_CANCELED: {
                forEachApply(new FuncUtils.MyConsumer<BillingProviderCallbacks>() {
                    @Override
                    public void accept(BillingProviderCallbacks billingProviderCallbacks) {
                        billingProviderCallbacks.onUserCanceledPurchase();
                    }
                });
                break;
            }
            case BillingClient.BillingResponse.ERROR: {
                forEachApply(new FuncUtils.MyConsumer<BillingProviderCallbacks>() {
                    @Override
                    public void accept(BillingProviderCallbacks billingProviderCallbacks) {
                        billingProviderCallbacks.onError();
                    }
                });
                break;
            }
            case BillingClient.BillingResponse.ITEM_ALREADY_OWNED: {
                forEachApply(new FuncUtils.MyConsumer<BillingProviderCallbacks>() {
                    @Override
                    public void accept(BillingProviderCallbacks billingProviderCallbacks) {
                        billingProviderCallbacks.onItemAlreadyOwned();
                    }
                });
                break;
            }
        }
    }
}
	package com.noctua.billing;

	import android.app.Activity;
	import android.support.annotation.Nullable;

	import com.android.billingclient.api.Purchase;

	import java.util.List;

	/**
	* Created by wldev on 8/28/17.
	*/

	public interface BillingProvider {
	void connect();

	void disconnect();

	void addCallbackListener(BillingProviderCallbacks callbackListener);

	void removeCallbackListener(BillingProviderCallbacks callbackListener);

	boolean launchItemPurchase(Activity activity, String skuId);

	boolean launchSubPurchase(Activity activity, String skuId, @Nullable String oldSku);

	List<Purchase> getMyPurchases();
	}
	package com.noctua.billing;

	import android.app.Activity;
	import android.content.Context;
	import android.os.Handler;
	import android.os.Looper;
	import android.support.annotation.NonNull;
	import android.support.annotation.Nullable;
	import android.support.annotation.UiThread;
	import android.text.TextUtils;
	import android.util.Log;

	import com.android.billingclient.api.BillingClient;
	import com.android.billingclient.api.BillingClientImpl;
	import com.android.billingclient.api.BillingClientStateListener;
	import com.android.billingclient.api.BillingFlowParams;
	import com.android.billingclient.api.Purchase;
	import com.android.billingclient.api.PurchasesUpdatedListener;
	import com.noctua.common.FuncUtils;

	import java.lang.ref.WeakReference;
	import java.util.ArrayList;
	import java.util.List;

	/**
	* Created by wldev on 8/28/17.
	*/

	public class BillingProviderImpl implements BillingProvider, PurchasesUpdatedListener, BillingClientStateListener {

	private static final String TAG = BillingProviderImpl.class.getSimpleName();
	private BillingClient mBillingClient;
	private Handler uiHandler;

	private final Context appContext;

	private List<BillingProviderCallbacks> billingProviderCallbacks = new ArrayList<>();

	public BillingProviderImpl(Context context) {
	appContext = context;
	mBillingClient = new BillingClient.Builder(context).setListener(this).build();
	uiHandler = new Handler(Looper.getMainLooper());
	}


	@Override
	public void connect() {
	if (Looper.myLooper() == Looper.getMainLooper()) {
	connectOrCreate();
	} else {
	connectOnUI();
	}
	}

	@Override
	public void disconnect() {
	if (billingProviderCallbacks.isEmpty()) {
	if (Looper.myLooper() == Looper.getMainLooper()) {
	disconnectAndClear();
	} else {
	disconnectOnUI();
	}
	} else {
	Log.d(TAG, "You can't disconnect service while there is at least one listener");
	}
	}

	private void connectOrCreate() {
	Log.d(TAG, "connectOrCreate: " + (mBillingClient == null));
	if (mBillingClient == null) {
	mBillingClient = new BillingClientImpl.Builder(appContext).setListener(this).build();
	}
	mBillingClient.startConnection(this);
	}

	private void disconnectAndClear() {
	Log.d(TAG, "disconnectAndClear: " + (mBillingClient != null));
	if (mBillingClient != null) {
	mBillingClient.endConnection();
	mBillingClient = null;
	}
	}

	@Override
	public void addCallbackListener(BillingProviderCallbacks callbackListener) {
	billingProviderCallbacks.add(callbackListener);
	}

	@Override
	public void removeCallbackListener(BillingProviderCallbacks callbackListener) {
	billingProviderCallbacks.remove(callbackListener);
	}

	@Override
	public boolean launchItemPurchase(final Activity activity, final String skuId) {
	if (mBillingClient.isReady()) {
	if (Looper.myLooper() == Looper.getMainLooper()) {
	launchBillingFlow(activity, BillingClient.SkuType.INAPP, skuId, null);
	} else {
	launchItemPurchaseOnUI(activity, skuId);
	}
	return true;
	} else {
	return false;
	}
	}

	@Override
	public boolean launchSubPurchase(final Activity activity, final String skuId, @Nullable final String lastSubSku) {
	if (mBillingClient.isReady()) {
	if (Looper.myLooper() == Looper.getMainLooper()) {
	launchBillingFlow(activity, BillingClient.SkuType.SUBS, skuId, lastSubSku);
	} else {
	launchSubPurchaseOnUI(activity, skuId, lastSubSku);
	}
	return true;
	} else {
	return false;
	}
	}

	@Override
	public void onBillingSetupFinished(@BillingClient.BillingResponse int resultCode) {
	Log.d(TAG, "onBillingSetupFinished() called with: resultCode = [" + resultCode + "]");
	if (billingProviderCallbacks != null) {
	switch (resultCode) {
	case BillingClient.BillingResponse.OK: {
	forEachApply(new FuncUtils.MyConsumer<BillingProviderCallbacks>() {
	@Override
	public void accept(BillingProviderCallbacks billingProviderCallbacks) {
	billingProviderCallbacks.onBillingServiceConnected();
	}
	});
	break;
	}
	default: {
	notifyAllListenersAboutError(resultCode);
	break;
	}
	}
	}
	}

	@Override
	public void onBillingServiceDisconnected() {
	forEachApply(new FuncUtils.MyConsumer<BillingProviderCallbacks>() {
	@Override
	public void accept(BillingProviderCallbacks billingProviderCallbacks) {
	billingProviderCallbacks.onBillingServiceDisconnected();
	}
	});
	}

	@Override
	public void onPurchasesUpdated(@BillingClient.BillingResponse int responseCode, List<Purchase> purchases) {
	Log.d(TAG, "onPurchasesUpdated() called with: responseCode = [" + responseCode + "], purchases = [" + purchases + "]");
	if (billingProviderCallbacks != null) {
	switch (responseCode) {
	case BillingClient.BillingResponse.OK: {
	handlePurchases(purchases);
	break;
	}
	default: {
	notifyAllListenersAboutError(responseCode);
	break;
	}
	}
	}
	}

	private void handlePurchases(@Nullable final List<Purchase> purchases) {
	forEachApply(new FuncUtils.MyConsumer<BillingProviderCallbacks>() {
	@Override
	public void accept(BillingProviderCallbacks billingProviderCallbacks) {
	billingProviderCallbacks.onPurchasesListUpdated(purchases);
	}
	});
	}


	private void launchItemPurchaseOnUI(final Activity activity, final String skuId) {
	final WeakReference<Activity> activityWeakReference = new WeakReference<>(activity);
	final WeakReference<String> skuIDWeakReference = new WeakReference<>(skuId);
	uiHandler.post(new Runnable() {
	@Override
	public void run() {
	if (activityWeakReference.get() != null && skuIDWeakReference.get() != null) {
	launchBillingFlow(activityWeakReference.get(), BillingClient.SkuType.INAPP, skuId, null);
	}
	}
	});
	}

	private void launchSubPurchaseOnUI(Activity activity, final String skuId, @Nullable final String oldSku) {
	final WeakReference<Activity> activityWeakReference = new WeakReference<>(activity);
	final WeakReference<String> skuIDWeakReference = new WeakReference<>(skuId);
	uiHandler.post(new Runnable() {
	@Override
	public void run() {
	if (activityWeakReference.get() != null && skuIDWeakReference.get() != null) {
	launchBillingFlow(activityWeakReference.get(), BillingClient.SkuType.SUBS, skuId, oldSku);
	}
	}
	});
	}

	@UiThread
	private void connectOnUI() {
	if (!mBillingClient.isReady()) {
	uiHandler.post(new Runnable() {
	@Override
	public void run() {
	connectOrCreate();
	}
	});
	}
	}

	@UiThread
	private void disconnectOnUI() {
	if (mBillingClient.isReady()) {
	uiHandler.post(new Runnable() {
	@Override
	public void run() {
	disconnectAndClear();
	}
	});
	}
	}

	private void forEachApply(@NonNull FuncUtils.MyConsumer<? super BillingProviderCallbacks> consumer) {
	for (int i = 0; i < billingProviderCallbacks.size(); i++) {
	consumer.accept(billingProviderCallbacks.get(i));
	}
	}

	@Override
	public List<Purchase> getMyPurchases() {
	List<Purchase> purchases = new ArrayList<>();
	if (mBillingClient != null && mBillingClient.isReady()) {
	Purchase.PurchasesResult inApps = mBillingClient.queryPurchases(BillingClient.SkuType.INAPP);
	if (inApps != null && inApps.getPurchasesList() != null) {
	purchases.addAll(inApps.getPurchasesList());
	}
	Purchase.PurchasesResult subs = mBillingClient.queryPurchases(BillingClient.SkuType.SUBS);
	if (subs != null && subs.getPurchasesList() != null) {
	purchases.addAll(subs.getPurchasesList());
	}
	}
	Log.d(TAG, "getMyPurchases() returned: " + purchases.size());
	return purchases;
	}

	private void launchBillingFlow(Activity activity, @BillingClient.SkuType String skuType, String sku, @Nullable String oldSku) {
	BillingFlowParams.Builder paramsBuilder = new BillingFlowParams.Builder().setSku(sku).setType(skuType);
	if (!TextUtils.isEmpty(oldSku)) {
	paramsBuilder.addOldSku(oldSku);
	}

	int response = mBillingClient.launchBillingFlow(activity, paramsBuilder.build());
	if (response != BillingClient.BillingResponse.OK) {
	notifyAllListenersAboutError(response);
	}
	}

	private void notifyAllListenersAboutError(@BillingClient.BillingResponse int billingResponse) {
	switch (billingResponse) {
	case BillingClient.BillingResponse.BILLING_UNAVAILABLE:
	case BillingClient.BillingResponse.SERVICE_UNAVAILABLE:
	case BillingClient.BillingResponse.DEVELOPER_ERROR: {
	forEachApply(new FuncUtils.MyConsumer<BillingProviderCallbacks>() {
	@Override
	public void accept(BillingProviderCallbacks billingProviderCallbacks) {
	billingProviderCallbacks.onBillingServiceUnAvailable();
	}
	});
	}
	case BillingClient.BillingResponse.SERVICE_DISCONNECTED: {
	forEachApply(new FuncUtils.MyConsumer<BillingProviderCallbacks>() {
	@Override
	public void accept(BillingProviderCallbacks billingProviderCallbacks) {
	billingProviderCallbacks.onBillingServiceDisconnected();
	}
	});
	break;
	}
	case BillingClient.BillingResponse.USER_CANCELED: {
	forEachApply(new FuncUtils.MyConsumer<BillingProviderCallbacks>() {
	@Override
	public void accept(BillingProviderCallbacks billingProviderCallbacks) {
	billingProviderCallbacks.onUserCanceledPurchase();
	}
	});
	break;
	}
	case BillingClient.BillingResponse.ERROR: {
	forEachApply(new FuncUtils.MyConsumer<BillingProviderCallbacks>() {
	@Override
	public void accept(BillingProviderCallbacks billingProviderCallbacks) {
	billingProviderCallbacks.onError();
	}
	});
	break;
	}
	case BillingClient.BillingResponse.ITEM_ALREADY_OWNED: {
	forEachApply(new FuncUtils.MyConsumer<BillingProviderCallbacks>() {
	@Override
	public void accept(BillingProviderCallbacks billingProviderCallbacks) {
	billingProviderCallbacks.onItemAlreadyOwned();
	}
	});
	break;
	}
	}
	}
	}