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Good day, everyone. Welcome back.

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Everything we've done so far in the course has been using the debug build.

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That's great while developing,

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as it allows all our debug log entries to appear in the logcat.

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You wouldn't normally want to take up space on the user's phone

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with huge log files,

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and the debug log entries are stripped out of the release build.

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As I mentioned, any code that's dependent on

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buildConfig.DEBUG being true

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also won't be compiled into the release version of the app.

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It gets better than that.

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Any classes you put into that debug folder,

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the one we created, and that's showing with (debug) in parentheses

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after the package name in the project pane

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those classes won't be compiled into the release version either.

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We can check that to make sure.

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From the build menu,

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choose the option build bundles/apks

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and then build apks.

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When the build is finished, a dialog pops up at the bottom

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of the android studio window.

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Click the link to analyze the apk. The apk,

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by the way, is the file that's used to deploy your package.

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You may have noticed messages about apk

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when running your apps from android studio.

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An apk file is just a zip file,

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containing everything that the app needs in order to run.

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All your classes and resources are included in the apk file.

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In earlier versions of android studio,

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you had to extract the contents of the apk zip file

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and examine it using your computer's file manager

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or a terminal session. Now things are much easier.

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Android studio has an apk analyzer.

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This gives a neat summary of the sizes of the various parts.

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You can see, for example,

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if your res folder is making up a large percentage of the overall size.

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The raw file size of this app is around 2.5 megabytes

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with our resources, icons, images and so forth

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making up nearly 400 kilobytes of that.

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If you've got a lot of images, that value might be a lot higher.

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We'll look at reducing the value a bit later.

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When we use vector graphics for our icons instead of png files.

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Okay. Most of the app size

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is the classes.dex.

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So click on that to get a more detailed breakdown in the bottom part of the window.

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That shows the various packages that make up the app.

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Android x makes up a lot of the total space used

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and that's things like the new support libraries that we're using in our app,

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the recyclerview, for example.

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Google are working on ways to share things like android x amongst apps.

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At the moment, those libraries are compiled into each app that uses them.

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Obviously that's not very efficient,

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but there are problems with allowing them to be shared.

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When google sorts it out, app sizes will shrink substantially.

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Expand the android x entry.

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And you'll see that appcompat is a substantial amount of the total.

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That will be support in the android package

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if you haven't converted your app to use android x.

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These figures don't add up by the way.

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So don't try to balance the sizes in the bottom part of the screen

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with those in the top part.

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There's all sorts of clever compression techniques going on here.

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Use the sizes as a relative measure of the various packages

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and don't try to equate those bottom figures with the top ones.

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What we're really interested in are the entries for our packages.

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I called my package learnprogramming.academy.doxtimer.

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So I have to expand that to see more details about it.

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If you used a different domain, expand the relevant entry in the list.

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The entry we're interested in at the moment under

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learnprogramming.academy.doxtimer is a debug entry.

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In there, we can see our testData class.

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So in the debug build that class is included.

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Close the window then go to build,

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select build variant.

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You may need to click in an editor window

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to enable that entry in the menu.

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Although it doesn't look like it, the build variant box on the left is a drop down.

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Click it, then select release.

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We can now create a release apk, using build,

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build bundles build apks again.

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All we could do if we didn't have an error in main activity.

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The test data class is no longer available.

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When you create a release build, anything in the debug directory

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doesn't get included.

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That means the release build

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has no knowledge of our testData class.

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In fact, if you check the project pane,

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the debug package isn't even showing up.

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Main activity is showing two errors.

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There's one when we try to use the testData class in the

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on options item selected,

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and the others in the import section

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when the program tries to import that class.

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In a release build, anything in debug

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just doesn't exist effectively.

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So there's no chance of us accidentally, including these debug classes,

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testData and test timing in the release version of our app.

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The app just won't compile.

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This isn't the most sophisticated way of handling this.

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If you work for a company developing android apps,

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you'll probably find they have more advanced processes in place.

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But as a developer, this technique is a good start

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to make sure you don't include debug classes

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in the apps that you deploy.

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Create a debug package as we've done here,

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and there's no chance of messing up by giving users things

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they really shouldn't be seeing.

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When you want to deploy your app, comment out the code that's giving the error.

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You may also have an error whenever buildConfig is used.

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If that happens, rebuild the project from the build menu.

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To check what's in our release apk, go to the build menu again

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and choose build bundles,

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build apks.

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Then click the analyze link in the dialog.

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It may take a while to create a release build.

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Keep an eye on the progress at the bottom of the screen.

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Click classes.dex.

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Then expand your package name

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learnprogramming.academy.doxtimer.

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Learnprogramming.academy.doxtimer in my case.

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Notice that the debug entry isn't present.

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That class just doesn't exist in build.

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The raw file size is also smaller than it was.

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A lot of other debug stuff has been stripped out of the release version,

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including all our log.d calls.

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Okya. Close the analyzer.

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Then make sure you set the build type back to debug.

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Build,

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select build variant,

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debug.

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That's important because you can't run a release build without signing it

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and we'll be covering that in a later video.

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I better uncomment those two lines as well.

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We've now got a way to generate test data in our app,

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and we've seen how to avoid accidentally giving users access to the testData class.

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Even if we somehow ship a version with that generate menu item enabled,

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it won't work for our users.

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That's a good thing

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because trying to unscramble test data from their live data

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would be far from trivial.

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If you make a mistake and ship a version of the app

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with that menu option enabled, it'll crash when they tap it.

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That's not good.

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What all you have to do is deploy a fixed version.

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If you left the testData class in, the app wouldn't crash.

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Instead, it would add a load of rogue records to their database,

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explaining to your users that the data they've collected over the last

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year is useless isn't something you want to have to do.

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In the next video, we'll make a start on displaying reports about the data that we've got.

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I'll see you there.