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Let's finish up our custom intent and filter combo by creating a new intent filter in a second app.
I mentioned Content Providers, which are used to share content between apps. The Android Developer Site has extensive documentation on Content Providers if you need to learn more about them, and stay tuned for future material on them here at Treehouse!
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So now we just need to create a new
App to receive this custom intent.
0:00
Let's create a new project.
0:05
File, new, new project and
let's name this CustomIntentTester.
0:06
Just leave all the defaults click Next,
Next,
0:14
select empty activity, next and finish.
0:18
Okay so all we want to do here
is add a new intent filter.
0:26
Let's open up the manifest.
0:29
So here in manifest,
double click on it, and
0:31
we can just add a second intent
filter to main activity.
0:34
Activities can filter as many
intents as we can throw them.
0:37
So under the first one let's add
a line in the new intent filter.
0:40
And now let's add an action element,
action and then enter a name and
0:46
for the name, we want to use the exact
value we defined in our other app.
0:52
I'm going to copy and
paste it to make sure I don't get a typo.
0:57
So let's switch over here and in detail
activity, we defined it at the top.
1:00
I'm gonna copy the string value, switch
back, and paste it here as the name.
1:05
All I need to do is end my action,
and now I'm set.
1:12
For the category,
1:15
remember that implicit intents require
us to use the default category.
1:17
So let's add category, and recall name and
1:20
then it's already at the top
of my list category default.
1:24
All right, so now we need to do
something with it in main activity.
1:29
Let's go back there and let's just
display the song details in a TextView.
1:31
First will need an ID for the TextView.
1:36
So let's open up the layout file.
1:38
And we have a Hello World TextView.
1:42
I'm going to delete the text and then add
1:44
android:id=@+/textView.
1:49
Let's go back to main activity and
1:55
now we can create a text
view named text view.
1:59
And set it equal to a cast to text
view FindViewById(R.id.textview).
2:05
Next we can get the intent
used to start this activity.
2:13
Intent intent equals getIntent.
2:15
So first we want to check the action to
make sure that this is the right intent.
2:19
So like before, we wanna lead with
the string in case the action is null.
2:24
So we say if string value, which I
happened still have in my clipboard,
2:27
that equals then we pass
in intent.getAction.
2:32
That's in curly braces and
now we need a song class again.
2:36
There are actually
a couple ways to do this.
2:42
I wanna show you how to make it
work with a parcelable class, but
2:44
that means we need to copy
the song class into this app.
2:48
That's fine for now but
2:51
we should always be wary of having
the same code in two places.
2:53
If we really wanna share
models across apps,
2:56
we should package them into a jar file.
2:58
Anyhow, let's go back to Music Machine.
3:01
Open up the Songs class in the Models
package, right-click on it and
3:03
select Copy.
3:07
Go back to our custom intent tester,
right click on the main package here and
3:10
select paste.
3:14
Click OK and
here's our song class once again.
3:16
So now we can use this
back in main activity.
3:20
We'll say song
song=intent.getParcelableExtra.
3:23
And for the name we will use EXTRA_SONG.
3:29
Notice that we need to be really careful
to use the exact same value that we have
3:36
in our other app.
3:40
It's starting to feel a little brittle.
3:42
Perhaps these both should be
defined in the song class itself.
3:44
I'll leave that as an exercise for
you if you want to clean it up.
3:47
Now we can print the song
details in the text view.
3:51
TextView.setText(song.toString).
3:54
I overwrote the to string method to
print the details out line after line.
4:01
So let's try this out.
4:06
Let's run the app.
4:07
Pick the same emulator.
4:09
OK and then when it loads let's
switch back to Music Machine.
4:13
Let's tap on a song and try to share.
4:18
Go to the menu tap on share song and
ouch we get an error
4:23
if we scroll up in logcat,
let's see what it says.
4:29
Okay, this says, BadParcelableException:
ClassNotFound when unmarshalling.
4:37
If you Google this error you can
read about problems trying to share
4:44
a parcelable object across apps.
4:47
Each app has its own Java class loader and
parceling in one app and
4:50
then unparceling in
another causes problems.
4:54
Fortunately, we can address that by
putting the class in the same exact
4:57
package on both apps.
5:00
So let's get rid of this log view and
5:03
right-click on Java here
in the project navigator.
5:06
Select New then Package
5:10
select the main package that's
already in here and click OK.
5:14
Now we want to type the package name
of our custom class from the other app.
5:17
So we have
com.teamtreehouse.musicmachine.models.
5:22
Click OK and there we go,
we have our new package.
5:31
So we can drag the song class in here now.
5:37
So I'm going to drag song in here.
5:40
Click on the re-factor button and
now let's try it again.
5:43
This time if we switch back to Music
Machine, and let's try sharing this again.
5:49
Click on the menu, share song,
and this time it worked.
5:56
Look we can see all the details of
the song in our custom intent tester.
6:01
I should point out another way to share
complex data from one app to another.
6:07
We can choose to implement
a content provider
6:10
which is used to provide different types
of content to other apps that ask for it.
6:13
The classic example is the Photos
app which provides images or
6:17
videos when other apps
prompt the user to pick one.
6:21
Now we won't cover content
providers in this course but
6:24
check the teacher's notes for
more information if you're interested.
6:27
All right.
We've built up a solid understanding of
6:31
intents.
6:33
We've used both explicit and implicit
intents and now understand why you can set
6:34
a specific activity for an intent and
sometimes let Android find a handler.
6:39
We've also seen how to
be good listeners and
6:44
set up an activity to
handle certain intents.
6:45
Will take this further in the next
section where we'll learn how to
6:48
listen across the entire Android system
with a tool called broadcast receivers.
6:51
See you there.
6:56
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