Android Development, the Right Way

Current tools, essential libraries, and some best practices. This talk was for Google Developer Group Davao DevFest 2014.

Transcript

1. ANDROID DEVELOPMENT The Right Way
2. JAYSON BASAÑES CTO of Lifebit github.com/shiki
3. http://lifebit.com Available on both iOS and Android LIFEBIT
4. DAVAO CITY CLUBS for iOS and Android
5. Download Lifebit for iOS and Android jayson@basanes.net WUT • TOOLS • ESSENTIAL LIBRARIES • BEST PRACTICES
6. Download Lifebit for iOS and Android jayson@basanes.net TOOLS
7. Download Lifebit for iOS and Android jayson@basanes.net ANDROID STUDIO (0.8+) • Gradle-based build system • Improved Interface Designer • Better code completion and refactoring • Code analysis • Faster in every aspect
8. Download Lifebit for iOS and Android jayson@basanes.net buildscript { repositories { mavenCentral() } dependencies { classpath 'com.android.tools.build:gradle:0.12.+' } } apply plugin: 'com.android.application' dependencies { compile 'com.netflix.rxjava:rxjava-core:0.19.1' compile 'com.netflix.rxjava:rxjava-android:0.19.1' compile 'com.squareup.retrofit:retrofit:1.6.1' compile 'com.squareup.okhttp:okhttp-urlconnection:2.0.0' compile 'com.squareup.okhttp:okhttp:2.0.0' } android { compileSdkVersion 19 buildToolsVersion "20.0.0" defaultConfig { minSdkVersion 15 targetSdkVersion 19 versionCode 1 versionName "1.0" } buildTypes { debug { runProguard false } release { signingConfig signingConfigs.release runProguard true proguardFiles 'proguard-rules.pro' } } }
9. Download Lifebit for iOS and Android jayson@basanes.net Build Variants productFlavors { demo { applicationId "com.buildsystemexample.app.demo" versionName "1.0-demo" } full { applicationId "com.buildsystemexample.app.full" versionName "1.0-full" } }
10. Download Lifebit for iOS and Android jayson@basanes.net GENYMOTION • A lot faster than the Android Emulator • GPS, Battery, Accelerometer • Simpler interface
11. Download Lifebit for iOS and Android jayson@basanes.net VERSION CONTROL (GIT) • SourceTree + Bitbucket • History • Collaboration • Multiple build versions • Blame games
12. Download Lifebit for iOS and Android jayson@basanes.net CRASHLYTICS • Crash reporting • Logging • Analytics • Distribution
13. Download Lifebit for iOS and Android jayson@basanes.net ESSENTIAL LIBRARIES
14. Download Lifebit for iOS and Android jayson@basanes.net RETROFIT • REST client for Android and Java • Stupidly easy to use. • Uses Gson for JSON parsing square.github.io/retrofit
15. Download Lifebit for iOS and Android jayson@basanes.net RETROFIT public interface LifebitService { @GET("/users/{user}/bits") List<Bit> getUserBits(@Path("user") String user); } RestAdapter restAdapter = new RestAdapter.Builder() .setEndpoint("https://api.lifebit.com") .build(); ! LifebitService service = restAdapter.create(LifebitService.class); List<Bit> bits = service.getUserBits(“shiki"); Profit!
16. Download Lifebit for iOS and Android jayson@basanes.net OKHTTP • Efficient HTTP Client. Alternative to Apache's HTTPClient and java.net.HttpUrlConnection. • Can be used with Retrofit. • From their site: Perseveres when the network is troublesome square.github.io/okhttp
17. Download Lifebit for iOS and Android jayson@basanes.net OKHTTP OkHttpClient client = new OkHttpClient(); ! String run(String url) throws IOException { Request request = new Request.Builder() .url(url) .build(); ! Response response = client.newCall(request).execute(); return response.body().string(); }
18. Download Lifebit for iOS and Android jayson@basanes.net PICASSO • Image downloading and caching library. • Automatic memory and disk caching. • Mostly one-liners to load a remote image into an ImageView. • Supports: resizing, cropping, placeholders. • Can use OkHttp square.github.io/picasso
19. Download Lifebit for iOS and Android jayson@basanes.net PICASSO Picasso.with(context).load("http://i.imgur.com/DvpvklR.png").into(imageView); Picasso.with(context) .load(url) .resize(50, 50) .centerCrop() .into(imageView) Picasso.with(context) .load(url) .placeholder(R.drawable.user_placeholder) .error(R.drawable.user_placeholder_error) .into(imageView);
20. Download Lifebit for iOS and Android jayson@basanes.net EVENTBUS OR OTTO • publish-subscribe-style communication between components github.com/greenrobot/EventBus or square.github.io/otto
21. Download Lifebit for iOS and Android jayson@basanes.net EVENTBUS public class MessageEvent { /* Additional fields if needed */ } EventBus.getDefault().register(this); ! public void onEvent(MessageEvent event) { /* Do something */ }; MessageEvent event = new MessageEvent(); EventBus.getDefault().post(event);
22. Download Lifebit for iOS and Android jayson@basanes.net BUTTER KNIFE • View injection • No more findViewById boilerplate jakewharton.github.io/butterknife
23. Download Lifebit for iOS and Android jayson@basanes.net BUTTER KNIFE class ExampleActivity extends Activity { TextView title; TextView subtitle; TextView footer; ! @Override public void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.simple_activity); title = (TextView) findViewById(R.id.title); subtitle = (TextView) findViewById(R.id.subtitle); footer = (TextView) findViewById(R.id.footer); } } The old way
24. Download Lifebit for iOS and Android jayson@basanes.net BUTTER KNIFE class ExampleActivity extends Activity { @InjectView(R.id.title) TextView title; @InjectView(R.id.subtitle) TextView subtitle; @InjectView(R.id.footer) TextView footer; ! @Override public void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.simple_activity); ButterKnife.inject(this); } } Using injection
25. Download Lifebit for iOS and Android jayson@basanes.net BUTTER KNIFE Events @OnClick(R.id.submit) public void sayHi(Button button) { button.setText("Hello!"); }
26. Download Lifebit for iOS and Android jayson@basanes.net ROBOLECTRIC • Unit test framework • Runs outside of the emulator robolectric.org
27. Download Lifebit for iOS and Android jayson@basanes.net ROBOLECTRIC @RunWith(RobolectricTestRunner.class) public class MyActivityTest { ! @Test public void clickingButton_shouldChangeResultsViewText() throws Exception { Activity activity = Robolectric.buildActivity(MyActivity.class).create().get(); ! Button pressMeButton = (Button) activity.findViewById(R.id.press_me_button); TextView results = (TextView) activity.findViewById(R.id.results_text_view); ! pressMeButton.performClick(); String resultsText = results.getText().toString(); assertThat(resultsText, equalTo("Testing Android Rocks!")); } }
28. Download Lifebit for iOS and Android jayson@basanes.net BEST PRACTICES
29. Download Lifebit for iOS and Android jayson@basanes.net Aim for the latest Android version
30. Download Lifebit for iOS and Android jayson@basanes.net Beware of the 65K DEX methods limit Unable to execute dex: method ID not in [0, 0xffff]: 65536 Conversion to Dalvik format failed: Unable to execute dex: method ID not in [0, 0xffff]: 65536 • Choose third-party libraries wisely • Use Proguard if you can’t avoid it
31. Download Lifebit for iOS and Android jayson@basanes.net Use Proguard for release builds buildTypes { debug { runProguard false } release { signingConfig signingConfigs.release runProguard true proguardFiles 'proguard-rules.pro' } } • smaller, optimized, obfuscated builds
32. Download Lifebit for iOS and Android jayson@basanes.net # Obfuscation parameters: #-dontobfuscate -useuniqueclassmembernames -keepattributes SourceFile,LineNumberTable -allowaccessmodification # Keep Jackson stuff -keep class org.codehaus.** { *; } -keep class com.fasterxml.jackson.annotation.** { *; } # Keep these for GSON and Jackson -keepattributes Signature -keepattributes *Annotation* -keepattributes EnclosingMethod # Keep Retrofit -keep class retrofit.** { *; } -keepclasseswithmembers class * { @retrofit.** *; } -keepclassmembers class * { @retrofit.** *; } # Keep Picasso -keep class com.squareup.picasso.** { *; } -keepclasseswithmembers class * { @com.squareup.picasso.** *; } -keepclassmembers class * { @com.squareup.picasso.** *; }
33. Download Lifebit for iOS and Android jayson@basanes.net Prefer Maven dependencies instead of jar files dependencies { compile 'com.squareup.okio:okio:1.0.+' compile 'com.squareup.okhttp:okhttp:2.0.+' ! compile 'com.squareup.retrofit:retrofit:1.7.0' } • ez
34. Download Lifebit for iOS and Android jayson@basanes.net Not Invented Here • yet-another-image-loading library • Unless you can make something better in the little time that you have.
35. Download Lifebit for iOS and Android jayson@basanes.net Load heavy objects on demand Not class MyActivity extends Activity { private Service service; @Override public void onCreate(Bundle savedInstanceState) { ... service = restAdapter.create(LifebitService.class); } @OnClick(R.id.submit) public void onButtonClick(Button button) { List<Bit> bits = service.getBits(); // Do something with bits } }
36. Download Lifebit for iOS and Android jayson@basanes.net Load heavy objects on demand Not Not class MyActivity extends Activity { private Service service; ! Service getService() { if (service == null) { service = restAdapter.create(LifebitService.class); } return service; } ! @OnClick(R.id.submit) public void onButtonClick(Button button) { List<Bit> bits = getService().getBits(); // Do something with bits } }
37. Download Lifebit for iOS and Android jayson@basanes.net Know when to use background threads • API calls • Loading files • Anything that’s gonna take more than a second
38. Download Lifebit for iOS and Android jayson@basanes.net Know when to use background threads private class DownloadFilesTask extends AsyncTask<URL, Integer, Long> { protected Long doInBackground(URL... urls) { int count = urls.length; long totalSize = 0; for (int i = 0; i < count; i++) { totalSize += Downloader.downloadFile(urls[i]); publishProgress((int) ((i / (float) count) * 100)); // Escape early if cancel() is called if (isCancelled()) break; } return totalSize; } protected void onProgressUpdate(Integer... progress) { setProgressPercent(progress[0]); } protected void onPostExecute(Long result) { showDialog("Downloaded " + result + " bytes"); } } new DownloadFilesTask().execute(url1, url2, url3);
39. Download Lifebit for iOS and Android jayson@basanes.net View Holder Pattern public class MyAdapter extends BaseAdapter { @Override public View getView(int position, View view, ViewGroup parent) { ViewHolder holder; if (view != null) { holder = (ViewHolder) view.getTag(); } else { view = inflater.inflate(R.layout.whatever, parent, false); holder = new ViewHolder(view); view.setTag(holder); } holder.name.setText("John Doe"); // etc... return view; } static class ViewHolder { @InjectView(R.id.title) TextView name; @InjectView(R.id.job_title) TextView jobTitle; public ViewHolder(View view) { ButterKnife.inject(this, view); } } }
40. Download Lifebit for iOS and Android jayson@basanes.net Please do not ignore exceptions! try { List<Bit> bits = service.getBits(); ... } catch (APIException e) { // Something terrible has happened // but I am too lazy to handle this exception. // So f*ck you users! ! // Logging is not considered handling an exception! Log.d(getClass().getName(), e.getMessage()); }
41. Download Lifebit for iOS and Android jayson@basanes.net
42. Download Lifebit for iOS and Android jayson@basanes.net Please do not ignore exceptions! try { List<Bit> bits = service.getBits(); ... } catch (APIException e) { // If you are sure that the message is safe for the end user: showDialog(e.getMessage()); } Inform the user
43. Download Lifebit for iOS and Android jayson@basanes.net Please do not ignore exceptions! Throw it up the call chain private void loadBits() throws APIException { List<Bit> bits = service.getBits(); ... }
44. Download Lifebit for iOS and Android jayson@basanes.net Please do not ignore exceptions! Crash that motherf*cker try { List<Bit> bits = service.getBits(); ... } catch (APIException e) { // I am pretty sure that an exception will never happen, // but just in case: throw new RuntimeException(e); }
45. Download Lifebit for iOS and Android jayson@basanes.net Please do not ignore exceptions! Log to Crashlytics try { List<Bit> bits = service.getBits(); ... } catch (APIException e) { Crashlytics.logException(e); ! showDialog(e.getMessage()); }
46. Download Lifebit for iOS and Android jayson@basanes.net Enforced Coding Style • Everyone can read everyone’s shit • Unity through uniformity • Automate!
47. Download Lifebit for iOS and Android jayson@basanes.net Automated Tests • Robolectric, Robotium, whatever floats your boat • Pays off in the long run • Good luck convincing your boss ^_^x
48. Download Lifebit for iOS and Android jayson@basanes.net Find a Mentor • a.k.a. “Gamitan” • Pay it forward
49. Download Lifebit for iOS and Android jayson@basanes.net lastly
50. Download Lifebit for iOS and Android jayson@basanes.net Don’t believe everything that I just said.
51. Download Lifebit for iOS and Android jayson@basanes.net
52. Download Lifebit for iOS and Android jayson@basanes.net
53. Download Lifebit for iOS and Android jayson@basanes.net
54. Download Lifebit for iOS and Android jayson@basanes.net REFERENCES • androidweekly.net: Free weekly newsletter for the latest Android dev news, tutorials, articles, etc. • android-arsenal.com: List of free and paid Android libraries • github.com/futurice/android-best-practices: Android dev best practices
55. Download Lifebit for iOS and Android jayson@basanes.net GLHF! Slides will be up at speakerdeck.com/shiki