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00:00:00,610 --> 00:00:03,960
All right, let's switch to DetailActivity
and handle the data on that side.

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00:00:05,790 --> 00:00:07,836
Let's comment out these few lines
here because we aren't going to

3
00:00:07,836 --> 00:00:08,426
use them anymore.

4
00:00:08,426 --> 00:00:09,960
I'll just leave them here as reference.

5
00:00:11,460 --> 00:00:13,160
So we still want to use a null check but

6
00:00:13,160 --> 00:00:15,562
this time we're going to call
a different intent method.

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00:00:15,562 --> 00:00:21,650
If intent.get, and here we want
to use the getParcelableExtra,

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00:00:21,650 --> 00:00:23,530
since we're passing in parcelable data.

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00:00:24,580 --> 00:00:28,626
We passed in with MainActivity.EXTRA_SONG.

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00:00:28,626 --> 00:00:31,450
And we want to make sure that
this is not equal to null.

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00:00:33,990 --> 00:00:36,670
Okay, so now inside here,
it's not null, so

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00:00:36,670 --> 00:00:39,148
we can use that same line to
initialize a song variable.

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00:00:39,148 --> 00:00:42,433
Song song = and
I'm going to copy and paste.

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00:00:45,500 --> 00:00:47,590
And here we go,
now we have a song variable.

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00:00:49,020 --> 00:00:50,890
Now we can set the title
from this variable.

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00:00:50,890 --> 00:00:55,681
So titleLabel.setText, and
we can use song.getTitle, and we can also

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00:00:55,681 --> 00:01:00,560
initialize our favorite check box
because that is part of the song object.

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00:01:00,560 --> 00:01:07,492
So we can say favoriteCheckbox.setChecked
and we can use song.isFavorite.

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00:01:07,492 --> 00:01:08,630
We need one more thing.

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00:01:08,630 --> 00:01:12,030
Remember that we are tracking the position
of the song that was tapped on.

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00:01:12,030 --> 00:01:13,840
We can get it as an int ListPosition.

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00:01:13,840 --> 00:01:16,066
I'm actually gonna put that
outside this if statement.

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00:01:16,066 --> 00:01:22,920
So, int ListPosition = intent.getIntExtra.

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00:01:22,920 --> 00:01:27,160
And the name was
MainActivity.EXTRA_LIST_POSITION.

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00:01:27,160 --> 00:01:30,030
And the getInt method
requires a default value.

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00:01:30,030 --> 00:01:31,650
This is why we don't need to
put it inside of a check.

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00:01:31,650 --> 00:01:35,190
So if it's not there, we'll just use
a default and we should use 0 for a list.

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00:01:37,390 --> 00:01:39,620
To use this list position
back in MainActivity,

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00:01:39,620 --> 00:01:42,300
we want to pass it back as
a result in our result intent.

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00:01:43,490 --> 00:01:45,792
So here where we're putting extra data,

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00:01:45,792 --> 00:01:48,590
let's set on our line
result intent.putExtra.

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00:01:48,590 --> 00:01:51,959
And we'll use the same key,
MainActivity.EXTRA_LIST_POSITION, and

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00:01:51,959 --> 00:01:53,330
we'll pass in listPosition.

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00:01:55,820 --> 00:01:59,350
Notice that Android Studio automatically
added the final keyword, which we need

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00:01:59,350 --> 00:02:02,830
when we're referencing the variable inside
of an anonymous class like we are here.

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00:02:04,270 --> 00:02:07,260
The last piece of this puzzle
is back in MainActivity.

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00:02:07,260 --> 00:02:10,070
We want to show the favorite
heart if the song is checked.

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00:02:10,070 --> 00:02:13,290
So now instead of just logging
the boolean result down here,

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00:02:13,290 --> 00:02:15,570
let's use it to update the view.

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00:02:15,570 --> 00:02:20,930
First we need the position in the list int
position = and our intent is called data.

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00:02:20,930 --> 00:02:23,881
And like before, we can call getIntExtra,

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00:02:23,881 --> 00:02:27,805
pass in EXTRA_LIST_POSITION and
a default value of 0.

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00:02:27,805 --> 00:02:33,040
Now, how can we update an individual
view in a separate recycler view?

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00:02:33,040 --> 00:02:37,140
The solution is to update the underlying
data and then notify the adapter that

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00:02:37,140 --> 00:02:41,250
the data has been changed, and that the
item should be bound to the view again.

46
00:02:41,250 --> 00:02:44,185
We can update the data
using the Playlist class,

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00:02:44,185 --> 00:02:48,250
Playlist.songs, and this is an array,
so we can pass in the position,

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00:02:48,250 --> 00:02:52,575
and then we can set the favorite
value with setIsFavorite.

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00:02:53,810 --> 00:02:55,400
And we have the value stored in result.

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00:02:57,340 --> 00:03:00,260
To notify the adapter of
a change at a specific position,

51
00:03:00,260 --> 00:03:06,250
we'll call mAdapter.notifyItemChanged
at a certain position.

52
00:03:07,800 --> 00:03:09,210
Now we can run this to see it in action.

53
00:03:13,490 --> 00:03:15,290
So first we need to tap
on a song in the list.

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00:03:15,290 --> 00:03:18,870
I'll tap on this one, Live and
Die, and it's going to open up.

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00:03:18,870 --> 00:03:20,424
I'm going to check it as a favorite.

56
00:03:22,494 --> 00:03:25,924
And when we return to the MainActivity,
there we go,

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00:03:25,924 --> 00:03:27,990
we see our favorite heart icon.

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00:03:29,250 --> 00:03:31,830
Now if we go back in,
let's tap on Live and Die again.

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00:03:33,350 --> 00:03:36,110
We'll uncheck the checkbox,
and we'll return.

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00:03:38,140 --> 00:03:39,610
And the heart icon disappears.

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00:03:41,600 --> 00:03:45,320
Let's take another look at that table
of different types of communication.

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00:03:45,320 --> 00:03:48,740
We've fully covered how to pass both
simple and complex data back and

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00:03:48,740 --> 00:03:52,760
forth between activities,
using intents and extras.

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00:03:52,760 --> 00:03:54,900
Well, it still looks like
we have a lot to cover.

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00:03:54,900 --> 00:03:58,330
Understanding this foundation makes
the rest of these pretty easy.

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00:03:58,330 --> 00:04:01,250
It's the same basic idea over and over.

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00:04:01,250 --> 00:04:04,670
Share information as extra
data on an intent object, and

68
00:04:04,670 --> 00:04:06,760
then make sure that extra
data is handled somehow.

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00:04:08,110 --> 00:04:11,500
Remember, everything we've covered for
activities works the same way for

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00:04:11,500 --> 00:04:13,630
communicating to and from services too.

71
00:04:15,300 --> 00:04:16,680
Nice work so far.

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00:04:16,680 --> 00:04:20,030
I now intend to take a short break,
and I'll make it explicit

73
00:04:20,030 --> 00:04:24,070
by naming the activity that will
handle my intention, playing a game.

74
00:04:24,070 --> 00:04:25,780
You take a break, too, but come back soon,

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00:04:25,780 --> 00:04:29,250
because I wanna get back to those
implicit intents we touched on earlier.

76
00:04:30,440 --> 00:04:32,450
In fact, if you'd like,

77
00:04:32,450 --> 00:04:36,640
why don't you try creating an implicit
intent to share location on a map?

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00:04:36,640 --> 00:04:39,250
I'll leave a link in the teacher's
notes and you can try it out, and

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00:04:39,250 --> 00:04:41,960
then we can look at it
together in the next section.

80
00:04:41,960 --> 00:04:43,960
Be sure to watch even
if you get it working,

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00:04:43,960 --> 00:04:46,340
because I want to show
you some special cases.

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00:04:46,340 --> 00:04:46,840
Good luck.