Similar to having a conversation,

in fire base we receive real time updates to our data by listening for them.

Fire base provides an interface called child even listeners, that notifies us

when children of a give node have moved, been added, changed, or deleted.

In this application, since we're keeping it as simple as possible,

we're only going to worry about when a message is added to our messages node.

Let's show you what that looks like in code.

Hopping over into Android Studio, I'll open the MessagingActivity.

You remember that child event listener I mentioned just a second ago?

Let's have our activity implement that interface, so

we can indicate to Firebase that this activity knows what to do

with ChildEvents, such as messages being added and removed from our messages node.

Although we need to implement each of these methods from the interface

we're only going to provide a method body for onChildAdded.

In a real application,

you'd more than likely wanna provide some kind of logic for each event.

But we wanna get up and running with Firebase as quickly as possible, so

we'll only provide proper functionality for that one method.

Let's think about what we wanna do here.

Whenever Firebase tells us there's a new message, we wanna

add that message to our recycler view so that it is displayed on the screen.

So let's do just that.

Another cool thing that Firebase gives us is the easy serialization and

deserialization of our data.

That means that since we posted our message object as a child of the messages

reference.

We can simply request a messages object back from the dataSnapshot by passing

the Message.class, class literal to the dataSnapshot.getValue method.

Now that we have a message object, we'll call the addMessage method on our recycler

view's message adapter, and scroll down to the most recent message.

Finally, we've written code for what we wanna happen when changes occur in

their database, but we haven't indicated to Firebase that we can handle them.

To do that, we'll tell our messages reference that this activity knows how to

listen to changes in its data by calling the add ChildEventListener and

passing this, for this activity.

Let's run that code and verify that this works.

I'll also pull up an additional emulator in the Firebase real time database from

the console to verify to you that indeed this is syncing in real

time across all clients.

That just blows my mind, I hope you find it as exciting as I do.

Through this workshop I hope you've gotten a great glimpse

into how powerful Firebase's Realtime Database functionality truly is.

The possibilities of what it can do are truly limitless, and

I hope that we've helped you gain confidence in incorporating Firebase into

your applications, or perhaps sparked new ideas that you'll embark on next.

Thanks for watching.