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Android From The Trenches Lessons learned from having two apps in the top free category on Google play for over 3 years.

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@donnfelker donnfelker.com

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Two Apps In The Top 100

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What happens when your app gets into the top free category on Google Play?

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Quite a few things ...

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Here’s what should happen.

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Excitement!

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Joy!

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Got Monetization?

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Then let it rain.

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Kinda. Sometimes. Maybe Not.

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Here’s what really happens.

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Excitement!

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Joy!

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BUT THEN ...

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All Hell Breaks Loose

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Tons of Email Complaints, Crashes, Support Emails, Oh My!

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What are these crashes? Huh? These never happened in dev. java.io.IOException: Attempted read from closed stream. com.android.music.sync.common.SoftSyncException: java.io.IOException: Attempted read from closed stream. at com.android.music.sync.google.MusicSyncAdapter.getChangesFromServerAsDom(MusicSyncAdapter.java:545) at com.android.music.sync.google.MusicSyncAdapter.fetchDataFromServer(MusicSyncAdapter.java:488) at com.android.music.sync.common.AbstractSyncAdapter.download(AbstractSyncAdapter.java:417) at com.android.music.sync.common.AbstractSyncAdapter.innerPerformSync(AbstractSyncAdapter.java:313) at com.android.music.sync.common.AbstractSyncAdapter.onPerformLoggedSync(AbstractSyncAdapter.java:243) at com.google.android.common.LoggingThreadedSyncAdapter.onPerformSync(LoggingThreadedSyncAdapter.java:33) at android.content.AbstractThreadedSyncAdapter$SyncThread.run(AbstractThreadedSyncAdapter.java:164) Caused by: java.io.IOException: Attempted read from closed stream. at org.apache.http.impl.io.ChunkedInputStream.read(ChunkedInputStream.java:148) at org.apache.http.conn.EofSensorInputStream.read(EofSensorInputStream.java:159) at java.util.zip.GZIPInputStream.readFully(GZIPInputStream.java:212) at java.util.zip.GZIPInputStream.(GZIPInputStream.java:81) at java.util.zip.GZIPInputStream.(GZIPInputStream.java:64) at android.net.http.AndroidHttpClient.getUngzippedContent(AndroidHttpClient.java:218) at com.android.music.sync.api.MusicApiClientImpl.createAndExecuteMethod(MusicApiClientImpl.java:312) at com.android.music.sync.api.MusicApiClientImpl.getItems(MusicApiClientImpl.java:588) at com.android.music.sync.api.MusicApiClientImpl.getTracks(MusicApiClientImpl.java:638) at com.android.music.sync.google.MusicSyncAdapter.getChangesFromServerAsDom(MusicSyncAdapter.java:512) ... 6 more

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How to mitigate? Be proactive.

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Unit Testing With JUNit, Robolectric & Mockito

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Whoa Whoa Whoa I didnt say it was perfect

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Example @RunWith(RobolectricTestRunner.class) public class SomeValueServiceImplTest { UserValueService uvs; UserService user; @Before public void setup() { user = mock(UserService.class); // An interface when(user.getGoals()).thenReturn(mock(UserGoals.class)); // Mock another interface uvs = new UserValueService(user); } @Test public void shouldBeAbleToGetBasicWeightHeightInfo() { when(user.getGoals().getHeight()).thenReturn(1223.0012f); when(user.getGoals().getWeight()).thenReturn("1,223g"); assertThat(uvs.getHeightGoal()).isEqualTo(1223.0012f); assertThat(uvs.getWeightGoal()).isEqualTo("1,223g"); } }

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What Is this? assertThat(something) .isEqualTo(someOtherValue); Fest for Assertions & Fest For Android More Info: github.com/square/fest-android

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Espresso Googles Testing tools for Android

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Click on a spinner to open the item selection onView(withId(R.id.spinner_simple)).perform(click()); Click on the item 'Americano' onData(allOf(is(instanceOf(String.class)), is("Americano"))) .perform(click()); Verify that the TextView contains the String "Americano" onView(withId(R.id.spinnertext_simple)) .check(matches(withText(containsString("Americano"))));

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Automate It

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! For Android Run Monkey against your App & Devices

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adb -d shell monkey -p com.instagram.android -v 2000

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Automated Acceptance Testing

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I GOT 99 Devices and the problem is every single one

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Testing on Multiple Devices Sucks

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You Know Your Android Dev If your Desk Looks Like This

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Device Lab devicelab.vanamco.com

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Device Lab Yeah buddy

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Device Lab Makes it Better But Testing on Multiple Devices Still Sucks

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ADB and Spoon To The Rescue

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Automated Distributed Instrumentation Testing

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Cant Catch Everything Even Parachutes Have Holes

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This Still Happens

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Log uncaught & caught exceptions

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What about development vs production crashes and getting them confused?

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Use build variants in gradle

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build.gradle buildTypes { debug { packageNameSuffix '.debug' } release { proguardFile plugin.getDefaultDexGuardFile('dexguard-release.pro') proguardFile 'dexguard-project.txt' } }

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NO This was not a commercial or Ad for Crashlytics

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Lesson Watch Your Crashes

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In App Monitoring Made Easy

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Tons of Email

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Managing Email Load

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Case Management Auto Assignment Email Workflow and more

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TOOLS ZenDesk Desk.com Freshdesk UserVoice ...

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Defensive Coding

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Trying To Prevent

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Null Pointer Exception AKA - NPE

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NPE is your new BFF

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What Shouldn't be null, will be. Thanks, Murph

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SIMPLE EXAMPLE @Override public void onListItemClick(final ListView l, final View v, final int position, final long id) { super.onListItemClick(l, v, position, id); Toast.makeText(getActivity(), "Seems Legit!", Toast.LENGTH_SHORT).show(); } Seems Legit?

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PFFT, I WISH

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In Fragments We Have getActivity() Make sure you always assume its null

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Easy to fix NPE crashes occur in Every Production Android Application

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Lesson Always Check For Null Because at scale, it will be null Even when it should NEVER be null

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Software Patterns Keeping you sane and healthy

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Boss Man Says The app has to have the feature this release. I know you just heard about it and we're shipping this afternoon.

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Making a quick & easy update Done! Commit!

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Boss Man: Happy Your Teammates though?

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Seriously?

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Spaghetti Mmmmmmmm tasty

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Why?

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A house built upon a cardboard foundation is bound to eventually fall

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App Architecture Matters

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Software Patterns

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Dependency Injection

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Break Dependencies

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Use Dagger

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Compile Time Code Generation Limited Reflection

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Using Dagger

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Android Field Injection

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Example Android Injection From Android Bootstrap public class NewsListFragment extends ItemListFragment { @Inject protected BootstrapServiceProvider serviceProvider; @Inject protected LogoutService logoutService; @Override public void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); Injector.inject(this); } }

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POJO Constructor Injection GOOD

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Example Pojo CTOR Injection From Android Bootstrap public class LogoutService { protected final Context context; protected final AccountManager accountManager; @Inject public LogoutService(final Context context, final AccountManager accountManager) { this.context = context; this.accountManager = accountManager; } }

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Start This Today Instant Reward Flexibiity, composition, testing

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Dagger Deep Dive https://speakerdeck.com/jakewharton/android-apps-with-dagger

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How Do You Perform In App Communication?

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I Sure hope its not statics

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Pub Sub

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For Goodness Sake Use an Event Bus

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Easily communicate inside of an app Can over complicate the app though Tooling Helps

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Popular Frameworks Otto Green Robot Event Bus RxJava

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Well This Looks Like Fun 04-19 10:15:14.164 464-477/system_process D/BluetoothManagerService Stored bluetooth Name=,Address=22:22:67:56:65:B2 04-19 10:15:14.164 464-477/system_process I/InputManager Starting input manager 04-19 10:15:14.164 464-477/system_process I/SystemServer Bluetooth Manager Service 04-19 10:15:14.172 464-477/system_process I/SystemServer Input Method Service 04-19 10:15:14.172 464-477/system_process W/InputMethodManagerService Couldnt create dir.: /data/system/inputmethod 04-19 10:15:14.184 464-477/system_process W/ResourceType Failure getting entry for 0x7f060000 (t=5 e=0) in package 0 (error -75) 04-19 10:15:14.188 464-477/system_process E/Trace error opening trace file: No such file or directory (2) 04-19 10:15:14.188 464-477/system_process I/SystemServer Accessibility Manager 04-19 10:15:14.192 484-486/? D/SurfaceFlinger setOrientation, mFbdev=0xb8969e90, mFbDev->setOrientation=0xb6774e20, orientation=0 04-19 10:15:14.192 484-486/? I/gralloc_vbox86 setOrientation: orientation=0 04-19 10:15:14.192 464-477/system_process I/SystemServer Mount Servic 04-19 10:15:14.196 485-485/? E/WVMExtractor Failed to open libwvm.so 04-19 10:15:14.196 464-477/system_process I/SystemServer LockSettingsService 04-19 10:15:14.196 464-477/system_process I/SystemServer Device Policy 04-19 10:15:14.196 464-477/system_process I/SystemServer Status Bar 04-19 10:15:14.196 464-477/system_process I/SystemServer Clipboard Service 04-19 10:15:14.196 464-477/system_process I/SystemServer NetworkManagement Service 04-19 10:15:14.196 464-477/system_process I/SystemServer Text Service Manager Service 04-19 10:15:14.204 464-477/system_process I/SystemServer NetworkStats Service 04-19 10:15:14.204 464-477/system_process I/SystemServer NetworkPolicy Service 04-19 10:15:14.208 464-524/system_process E/EventHub could not get driver version for /dev/input/mouse3, Not a typewriter 04-19 10:15:14.208 464-537/system_process I/PackageManager No secure containers on sdcard 04-19 10:15:14.208 464-537/system_process E/MountService Error processing initial volume state java.lang.NullPointerException at com.android.server.MountService.updatePublicVolumeState(MountService.java:630) at com.android.server.MountService.access$1400(MountService.java:103) at com.android.server.MountService$3.run(MountService.java:723) 04-19 10:15:14.208 464-477/system_process I/SystemServer Wi-Fi P2pService

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Android Logs Are Terrible

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Log.wtf No, seriously, this really exists in Android

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Yup, Here It Is

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But Really, Here's the Issue Log.e(tag, ...) Log.d(tag, ...) Log.i(tag, ...) Log.v(tag, ...)

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I Like Line #s

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Like This 04-19 10:21:13.527 1152-1152/ com.myfitnesspal.android D/ COM.MYFITNESSPAL.ANDROID/ AbstractNavigationHelper.java:370 MFP main starting activity normally: Intent { act=android.intent.action.MAIN flg=0x16000000 cmp=com.myfitnesspal.android/ com.myfitnesspal.activity.Welcome2 }

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The Ln Logger From RoboGuice/ Android Bootstrap

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Forget the tags ! Ln.d("Hi") Ln.e(err, "Oh No!") Ln.i("Yo") Ln.v("Foo")

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Ln.java Provides » File Names » Line Numbers » Package Name » Default Verbose logging for debug builds » Built in String formatting

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Hugo Annotation-Triggered method call logging for your debug builds @DebugLog public String getName(String first, String last) { SystemClock.sleep(15); // Don't ever really do this! return first + " " + last; } Result D/Example: ⇢ getName(first="Bill", last="Cosby") D/Example: ⇠ getName [16ms] = "Bill Cosby"

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Hugo https://github.com/JakeWharton/hugo

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Deep Links

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Deep Links Built Properly Open up Business opportunities and growth

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What is a Deep Link? A URI your app intercepts and responds to I'm sure you've seen this happen with Twitter, YouTube, GooglePlus, Groupon and more

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What does one look like? URL BASED http://www.donnfelker.com/some/path CUSTOM donnfelker://path/to/something

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Defined in the AndroidManifest.xml

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Deep Links Drive Engagement

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Lets Talk About Fragments For a Minute

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FRAGMENTS You need them, even if you think you dont.

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Fragments are Good For » Responsive Layout » Screen and UX Composition » Hosting Fragments in Fragments » View Pagers » Sliding Drawer/etc

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Start with Fragments or Migrate Now. Waiting until later is expensive

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Do you even Build, Bro?

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Continuous Integration

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A core component For any team

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Options » Jenkins » TeamCity » Travis » and a bunch more ...

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Most Common Jenkins In House Travis Open Source

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What gets Measured Gets Managed

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Analytics & A/B Testing

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Google Analytics Localytics MixPanel Custom

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A/B Testing on Mobile?

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Very Similar to Other A/B Test Frameworks { "abtests": [ { name: "201404-loginButtonColor", variants : [ { name: "orange", data: { color: "#FF9900" } }, { name: "yellow", data: { color: "#FEFEDF" } } ] } ] }

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Yeah, its custom

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Commercial Solutions - Apptimize.com - Arise.io - LeanPlum.com - AppIterate.com - SplitForce.com - Vessel - and more ...

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Community

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Embrace Open Source

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Libraries - Dagger - Otto - Picasso - OkHttp - Retrofit - Spoon - Http-Request - RxJava - Gson - Jackson - Guava - Butterknife - Hugo

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Libraries Continued - Timber - Madge - Scapel - StaggeredGrid

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Bootstrap An App & Learning

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Three Great Options Android Bootstrap Android Kickstartr Jake Wharton's u2020

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Android Bootstrap

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Android Kickstartr

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Jake Wharton's u2020

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Read Great Code One of the best ways to learn

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Thats a Wrap

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Lessons Learned

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1. Prepare for Things to break

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2. Prepare to Support Your Customers

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3. Remind yourself to Stay Foolish and Stay Hungry

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Thank You Reach me at @donnfelker