10 Common mistakes that Android developers do Erik Hellman @ErikHellman - www.hellso!.se 

Erik Hellman Freelance So!ware Developer Stockholm, Sweden Previously Ericsson, Sony Mobile, Spotify (and more) Drinks most coffee Author of Android Programming - Pushing the Limits 



1. People are different 

Accessability (a11y) 

Accessibility in Action Kelly Shuster, DroidCon Berlin 2015 

Different form factors 

Stop doing this! 

2. Cross-platform assumptions 

Cross-platform tools 

Your first options 

HTML5 Service Worker if ('serviceWorker' in navigator) { navigator.serviceWorker.register('/sw.js') .then(function(registration) { // Registration was successful console.log('ServiceWorker registration successful!'); }) .catch(function(err) { // registration failed :( console.log('ServiceWorker registration failed: ', err); }); } 

Modern C++ // auto std::vector container = // fetch container... for (auto it = container.begin(); it != it.end(); it++) { // type of it is std::vector::iterator } // lambdas auto is_odd = [](int n) {return n%2==1;}; // Strongly typed enums enum class Options {None, One, All}; Options o = Options::All; 

3. Very long builds 

./gradle clean assembleDebug --profile 

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Don't forget the lead times of your PRs! 

4. Testing strategy 

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Too much or not at all? 

Automate all the things! 

5. Leaking contexts 

Looks familar? E/AndroidRuntime(379): FATAL EXCEPTION: main E/AndroidRuntime(379): java.lang.IllegalStateException: Activity has been destroyed E/AndroidRuntime(379): at android.support.v4.app.FragmentManagerImpl.enqueueAction(FragmentManager.java:1365) E/AndroidRuntime(379): at android.support.v4.app.BackStackRecord.commitInternal(BackStackRecord.java:595) E/AndroidRuntime(379): at android.support.v4.app.BackStackRecord.commitAllowingStateLoss(BackStackRecord.java:578) E/AndroidRuntime(379): at com.app.main.AppMainTabActivity.pushFragments(AppMainTabActivity.java:650) E/AndroidRuntime(379): at com.app.home.Home$ExpandableListAdapter$1.onClick(Home.java:530) E/AndroidRuntime(379): at android.view.View.performClick(View.java:2408) E/AndroidRuntime(379): at android.view.View$PerformClick.run(View.java:8816) E/AndroidRuntime(379): at android.os.Handler.handleCallback(Handler.java:587) E/AndroidRuntime(379): at android.os.Handler.dispatchMessage(Handler.java:92) E/AndroidRuntime(379): at android.os.Looper.loop(Looper.java:123) E/AndroidRuntime(379): at android.app.ActivityThread.main(ActivityThread.java:4627) E/AndroidRuntime(379): at java.lang.reflect.Method.invokeNative(Native Method) E/AndroidRuntime(379): at java.lang.reflect.Method.invoke(Method.java:521) E/AndroidRuntime(379): at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:868) E/AndroidRuntime(379): at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:626) E/AndroidRuntime(379): at dalvik.system.NativeStart.main(Native Method) 

– What do we want? – Now! – When do we want it? – Fewer race conditions! — Developers 

Leak Canary https://github.com/square/leakcanary 

@WorkerThread public void doNetworkStuff() { // Do network stuff here... } @MainThread public void doUiStuff() { // Update the UI here } 

6. Security mistakes 

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signingConfigs { release { storeFile file("./cert/release_keystore.jks") storePassword S3cr3tP4ssw0rd keyAlias android keyPassword S3cr3tP4ssw0rd } debug { storeFile file("./cert/debug_keystore.jks") storePassword "appdebug" keyAlias "debug" keyPassword "appdebug" } } 

7. Picking the right library! 

Emerging and Disruptive 

8. API Level 

Official stats (April 2016) 

Android versions 2015 

Exepctations vs Reality 

· Track actual usage · Perform user studies in public · Play Store keeps old versions available 

9. Get an iPhone! 

10. Sharing is caring 

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Thank you for listening! @ErikHellman - www.hellsoft.se