Google Play Services encompasses a lot of APIs,

and we needed to handle many edge cases to ensure our app doesn't crash.

By building a helper class we've simplified the interaction with

Google Play Services library, making it easier to reuse in future apps.

Now that our code is connecting to Google Play Services,

we'll be able to start using those APIs.

Let's handle the adapter first.

Remember the adapter is what actually creates our views and

displays them on the screen, and in on bind view holder, we can hide or

show views as we need to, so this is what's really going to

care about whether Google Play Services is available or is not available.

So let's go ahead and

add in a way to store and know whether Google Play Services is available or not.

Let's just store a boolean and we're going to call it, isGooglePlayServicesAvailable.

By default, we're just going to assume it's not available.

So that way, we make sure we handle that case.

So by default we're just gonna say false, and

now this is gonna need to know when Google Play Services becomes available.

So, in order to know that,

we're gonna use the interface that we defined in our helper.

So remember, let's go to our helper, and at the top we defined this interface

called GoogleServicesListener, and it has a method on connected on disconnected and

that's what our adapter wants to know is when it's connected and disconnected.

So let's going ahead and have it implement that interface.

There it is, GoogleServicesListener.

And now we need to ahead and use Alt+Return and

implement those methods on connected and on disconnected.

Add those to our class, we can see it added them down here.

And what's gonna happen when we're connected?

Well, when we're connected, we now know, okay, Google Play Services is available.

So first off, let's go ahead and set that value to be true.

Okay. And then, we need to go ahead and redraw

the items on screen, because by default we assumed that they weren't connected, so

we're probably displaying them in a different way.

But if they're, Google Play Services is now available,

we wanna display the options to plus one and share to Google+.

So, we're gonna call notifyDataSetChanged.

And this will cause this adapter and recycler re,

together to redraw those items.

And the same thing is gonna happen down here at on disconnected.

We're just going to say it's false now it's not available and

we want to make sure that we update the recycler view items to reflect that.

Okay and now that that's happening we can actually handle the cases where it's

available and not available in our on bind view holder method,

so up in our on bind view holder method, here we are.

Right here, we're just gonna add a place where later on,

we can check and display the UI in a different way.

So we're just gonna put this in here and make sure we come back to it later on, but

we'll have an opportunity to say, okay, if Google Play Services is available, we're

gonna be able to display that +1 button once we've added it in to each item, and

initialize it, initialize the share button, do whatever we need to do,

and we're also gonna handle the case where it's not available, and

that's gonna be our else case.

Okay, and because the listening adapter is the thing that actually gets the data,

holds our active listings object, displays the UI, let's go ahead and move the logic

of loading, doing the load to the network, calling Etsy.getActiveListings.

Let's move that into our adapter here.

So in our adapter, what we're gonna do is just check, when we call to

Google Play Services, it's either gonna come back as connected or disconnected.

So one of these cases, that's going to be the case every time we start our activity.

So, what we're gonna do here is just check and if it connects but

we don't have any items yet, we can use getItemCount equals 0.

That means we don't have any items yet.

We're gonna go ahead and now call to getActiveListings and we're gonna pass in

this because remember the adapter itself was the callback for retrofit.

And we're actually gonna, gonna do the same thing in disconnected as well.

So either way, we still wanna do the load to the API.

We wanna call that network and get the response back.

So, in either case, either we're connected or disconnected, but if we don't have any

data to show anyway we need to go ahead and start a network request.

So let's go ahead and do that.

Okay, now that we've moved the network request into the adaptor and

the adaptor handles when Google Play Services is available or not available.

We need to go ahead and modify our activity to account for this.

So, let's go to our activity and when we initialize our activity

we were initializing a calling here into API.

Well we don't wanna do that anymore.

We want to now create a Google Services helper object instead and initialize it.

So let's go ahead and add that in to our class.

So we create our googleServicesHelper object, and

then we're always going to initialize it.

And we need to initialize it after we create our adapter.

Because remember, our adapter is the listener for our googleServicesHelper.

So after this happens we can go ahead and call through to create a new helper here.

And the helper needs the activity.

That's this.

And it needs the listener which is the adapter.

And now we can remove the call to getActiveListings, because remember,

Google Services helper will call back to the adapters on connected or

on disconnected, and that will start the load to the API.

So, in either case, we don't need to do that in the activity anymore.

All we really need to do is just show loading.

So let's go ahead and move that in here.

We're just gonna say, show loading by default always.

And now, we're just gonna move this check to say, okay.

If the savings and state was not available and, we did have some saved data.

We're gonna go ahead and call through to success.

And if we look at success,

we're gonna see it, it, it's actually calling through to show the list already.

So, we don't even, we don't even need that anymore.

Let's go ahead and remove that as well.

Okay, and now that we have our googleServicesHelper object created,

we need to go ahead and connect or disconnect, and to do that, remember from

the documentation, we need to do this in our onStart and onStop methods.

So, let's go ahead and get those methods in here.

There's onStop and we gotta find onStart as well, down here.

Gonna implement those methods in our class and

we're just gonna call through to our helper object.

And onStop you wanna disconnect.

And in onStart we want to connect.

And I'm just gonna go ahead and

arrange these in the order that they would typically be called so

usually you'd connect first and then disconnect later on.

Okay and finally we need to handle those cases where we called through

to resolve an error or check availability with the googleServicesHelper.

And when doing that, remember it would call back to the activities

onActivityResult, so we need to add in that method as well.

So let's add that in here.

So onActivityResult, here, yep, and

we're going to simply pass that through to our helpers method.

Called handleActivityResult.

And we just, remember we were passing in the exact same parameters

that were coming through here.

Perfect.

And now, this will be able to handle those cases where

the result of the intent came back, it was good, handle the result, reconnect, etc.

Let's run the app and make sure everything is working before taking a break.

So we'll run it on my emulator, and we're gonna see when it runs, oh,

it has stopped, and that's because we can see right here that there's

an illegal argument exception that gets thrown,

and in our googleServicesHelper, it's telling us that we must call add API

to add at least one API before connecting to Google Play Services.

So, right now this isn't gonna be working, but in the next stage we're gonna add in

the Google Plus API and we're gonna get this working.

And we're gonna see those listings come up, and

be able to display that plus one and Share button.