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G'day everyone, welcome back.

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Did you work out why the app crashes and manage to fix it?

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We've seen the error before.

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I'll run the app, and crash by editing a task, making
a change and then using the Up button without saving.

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Because we included an informative
message in the appDialog class,

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it's easy to see what the problem is.

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We have to implement the dialog's callback interface,

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and of course, we'll have to implement the function,
which we'll do after the onBackPressed function.

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It's always worth checking the dialog ID,
even if you've only got one dialog.

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Strange things could happen if
someone adds another dialog later,

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and your callback function responds to any ID.

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Alright, that should stop the app from crashing,

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and we'll close the fragment if the user
confirms that they want to abandon the edit.

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I'll run the app in portrait and make
changes to one of the tasks.

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When I tap the Up button,
we get the confirmation dialogue.

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CONTINUE EDITING just closes the dialogue,
and the Edit fragment remains visible.

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I'll tap again.

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I'll tap again, and this time ABANDON
CHANGES.

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That's good, now we'll test the Back button,

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and we get the same behavior.

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Tapping Back, after making a change,
causes the dialogue to appear,

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and CONTINUE EDITING allows us to carry on making changes.

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Back again, and ABANDON CHANGES returns us to the main screen.

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The behavior's slightly different in landscape.

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Up works the same, but Back closes the
app without requesting confirmation.

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You may not like that behavior of course.

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You're free to design your apps however you want.

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This is how we decided to do it,

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but if you want to change it, to get a confirmation
if the user taps Back in landscape,

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then just remove the test for the mTwoPane, in onBackPressed.

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Okay, that's the confirmation dialogues.

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I wanted to show you how to use them from
a fragment, and from an activity,

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which is why we're confirming
leaving the addEditFragment.

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Google's UI guidelines suggest that
that's not really a good idea.

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Google recommend that we should just save
the data when the user taps the Up button,

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and cancel quietly if they use the Back button.

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Doing that would remove the need to have a Save button.

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We just call the saveTask function in
AddEditFragment's onPause or onStop functions.

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I suggest you do that, because the app
will work more like other Android apps,

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but don't do it yet.

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Wait until we finish the app, in case you
introduce a bug when making the change.

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In the next video, we'll have a look at Kotlin
extension functions and create a few more.

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See you in the next video.