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You can skip this video if you'd like! This is an optional solution to make your app force all Activities into portrait-only mode.
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All right let's take a look at how
to set portrait only mode in code.
0:00
Once again, this video is optional,
0:04
you don't need to watch this video to
complete the section or the course, but
0:06
it's here if you wanna go a bit further,
and try this out.
0:09
Don't worry if you don't fully
understand everything we cover here, but
0:11
certainly feel free to ask questions and
discuss with our community, right.
0:14
So to start, I'm going to get
rid of the screen orientation
0:18
attribute we just added, make sure
the angle bracket is still there.
0:20
And now, let's take a look at a helpful
stack overflow question about this
0:24
exact problem.
0:27
So here the question is, how to set an
entire application in portrait mode only?
0:28
If we go down to the first answer,
we see a helpful response, this is for
0:31
any Android version, but since our
app is targeting API level 16 and up,
0:36
we can use this other solution down here,
which I like better.
0:41
So, the basic idea is that we wanna create
custom activity lifecycle listeners,
0:44
inside of custom application class.
0:48
When an activity switched from portrait
to landscape, it goes through a number of
0:50
lifecycle methods, it's a actually
destroyed, and then recreated.
0:55
And when it's recreated
in this other mode,
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it gets a different layout if needed.
1:01
So we wanna do,
is attach a listener to those events, and
1:04
then when a certain event is called when,
the activity is created,
1:07
we want to force it,
into SCREEN_ORIENTATION_PORTRAIT.
1:10
All right,
let's see how this works in code.
1:15
So we'll start by creating
a custom application class,
1:16
right click on our main package here,
select New, Java Class,
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let's call this
InteractiveStoryApplication.
1:24
By convention,
if we do a custom application class,
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we usually end with the word Application.
1:31
As a Superclass,
let's start typing Application, and
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we can select android.app.Application,
and click OK.
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Okay, so here we have our new class, and
it's extending our base application.
1:39
The base application class is used
when an app first start ups, and
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there are methods there
that happen by default.
1:47
Now that we're using a custom one, we need
to specify that in the manifest itself, so
1:49
here for the application element,
we want to add a new attribute.
1:53
So drop it on a new line,
and type android:name and
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then in here we want the value,
we can start typing InteractiveStory, and
2:00
from auto complete,
we can select our new class.
2:05
So now,
Android knows when our app starts to
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use this custom application class
instead of the default one.
2:10
Back in our class, we want to override the
onCreate method, so start typing onCreate,
2:14
and we can select it from auto complete,
and this is the onCreate method for
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the entire application, not an individual
activity like we've seen before.
2:24
So back in our sample code we see that,
inside onCreate we want to register a new
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ActivityLifeCycleCallBack, and then in
there we're gonna use a specific method.
2:33
So, let's add a new line after
super.onCreate, we wanna make sure we call
2:39
that, so that it does all
the functionality in the superclass.
2:42
And now we wanna type register, and
there it is, ActivityLifecycleCallbacks.
2:45
And here we can add a new anonymous
inner class, we can type new
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ActivityLifecycleCallbacks, hit Enter, and
we get a bunch of methods we can override.
2:54
Now we don't have to do anything here,
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we're only going to override this
first one onActivityCreated,
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but you can see there are other methods
that we could override for other reasons.
3:03
So in here, when an activity is created,
we want to force it to portrait mode,
3:07
we do that by referencing
the activity that's passed in, and
3:12
on it we call setRequestedOrientation,
and we set it to portrait mode,
3:16
which we get through ActivityInfo, and
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I just remember this from the stack
overflow question, ActivityInfo.
3:23
And here we have a bunch of screen
orientation parameters, and
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we want SCREEN_ORIENTATION_PORTRAIT,
there we go.
3:31
So, if we run this we
should be able to see,
3:34
if we change our emulator to landscape
mode, it should stay portrait.
3:36
Okay it loads up, and we can use the
buttons here to switch, and sure enough,
3:40
it doesn't change to landscape view.
3:44
Cool, that's exactly what we wanted.
3:45
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