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all right so remote all our changes in

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the last three videos to our top ten

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downloader it's now time to check this

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out does it actually work what I'm gonna

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do first is put a log cat into floating

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mode so we can actually see this and

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we'll run our application as always I

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fast forward this to get it showing

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quickly

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all right so so far so good the app

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seems to be running but we've got a lot

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of data in the logging here

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I think we're logging a bit too much

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here so let's comment out some of this

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stuff so look at our paws applications

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class so let's move tag to be consistent

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outside of the class and also make it a

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constant and we'll also take the

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opportunity to remove the logging on

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line 16 so I want to just comment that

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line out again

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so let's now run the up again okay so I

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think there's a bit tidier and if you do

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get some error or information log

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entries from other parts of the system

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and I've got some there now you can

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filter them out what I'm going to do is

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just just show debug only errors but

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simple ways D capital D zap forward

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slash and you can see that makes it much

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easier to try and focus on just what

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we've got we've got a few other things

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there but it is a lot easy to see all of

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our entries now right so before checking

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for unnecessary downloads I want to make

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sure the app still works and it's just

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tab back over to that first thing I'm

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going to select songs from the list then

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we saw there that download our download

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URL got called if you scroll over and

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have a look we can see that other these

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songs was actually called there the

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download URL was called

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doing background was in turn called and

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because the URL had changed that set off

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the new async task the download the

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doing background was an executed from

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the download data racing task have feed

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view models on data available functions

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getting called there as you can see and

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when the live data object gets updated

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main activities picking up those changes

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and it's updating the data as you can

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see there in the interface so that's

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looking good let's try the top 25

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instead of the top 10 so select top 25

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you can see it clearly we've got more

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songs showing up there so that's good

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and in terms of our log entries with the

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top 25 being downloaded they're on data

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available being called again so so far

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so good just before I rotate the device

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I'm going to top an entry in the lock

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rotating and let's try rotating it now

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and see what happens

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and looking at the data you can see that

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data is still there clearly you've got

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that there but looking at the log entry

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though and accidentally scrolled in so I

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go back down to the end and see what

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happened so we've got our rotating it

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tree that I added there firstly notice

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notice how quick the data reloaded when

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I did rotate into landscape and that's

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because the data didn't have to be

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downloaded again and we can see there

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that the activities uncreate was called

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so activity was destroyed and recreated

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because of that that caused the download

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URL function to be called again and you

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can see it was called within them Anika

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was 25 again but this time because of

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the Euro hasn't changed and the v-model

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still has all the data

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there's no download needed you can see

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clearly there there wasn't a call to our

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download data async task as there was

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previously the adapters populated with

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the current data and the app appears

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much slicker than it did before and

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we've also saved battery life and

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avoided additional data costs for our

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users as well all right so that's pretty

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cool and now that brings to an end this

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section in our introduction to view

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model and live data so keep in mind that

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Google have now deprecated the lower

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classes but if you use them I think

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you'll agree that the view model that

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replaces them is easy to use and I think

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it's more flexible as well combined with

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live data it's a great way to separate

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your UI from other logic and also solves

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many of the lifecycle problems that we

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sometimes struggle with Android

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development now a lot easier as a result

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will be using view model again in our

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data base app we originally used to

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cursorloader but now that that's been

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deprecated we've rewritten it to use a

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view model instead so we'll see you in

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the next section when we start work on

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that