Building complex apps easily Mustafa Ali 

Building a good app is hard 

“If I have seen farther than others, it is by standing on the shoulders of giants.” - Isaac Newton Mt. St. Helens Crater Rim by brookehoyer (CC-BY SA) 

Writing boilerplate code sucks 

Butter Knife View “injection” library for Android Eliminates boilerplate code Performs annotation-based code generation No reflection Can “inject” listeners as well jakewharton.github.io/butterknife 

Butter Knife Usage public 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); // TODO Use "injected" views... } } public void inject(ExampleActivity a) { a.subtitle = (android.widget.TextView) a.findViewById(2130963232); a.footer = (android.widget.TextView) a.findViewById(21309685455); a.title = (android.widget.TextView) a.findViewById(21309686566); } 

Butter Knife Usage @OnClick(R.id.submit) public void sayHi(Button button) { button.setText("Live long and prosper"); } @OnClick({ R.id.door1, R.id.door2, R.id.door3 }) public void pickDoor(DoorView door) { if (door.hasPrizeBehind()) { Toast.makeText(this, "You win!", LENGTH_SHORT).show(); } else { Toast.makeText(this, "DIE DIE DIE!", LENGTH_SHORT).show(); } } @OnItemSelected(R.id.list_view) void onItemSelected(int position) { // Do something with the “chosen one” } @OnItemSelected(value = R.id.maybe_missing, callback = NOTHING_SELECTED) void onNothingSelected() { // Y u no select anything? } 

Integrating APIs is tricky GET, PUT, POST …. WUT??? 

Retrofit Type-safe REST client for Android and Java Turns your REST API into a Java interface Each HTTP verb is represented by an annotation Requests can be both synchronous & asynchronous Automatic deserialization using GSON, Simple, etc square.github.io/retrofit 

Retrofit Usage public interface GoogleBooksService { @GET("/books/v1/volumes") void search(@Query("q") String query, Callback callback); } GET https://www.googleapis.com/books/v1/volumes?q=android RestAdapter restAdapter = new RestAdapter.Builder() .setEndpoint("https://www.googleapis.com") .setLogLevel(RestAdapter.LogLevel.FULL) .build(); GoogleBooksService service = restAdapter.create(GoogleBooksService.class); 

Synchronous SearchResult result = service.search(query); Retrofit Usage Asynchronous service.search(query, callback); private Callback callback = new Callback() { @Override public void success(SearchResults searchResults, Response response) { displayResults(searchResults); } @Override public void failure(RetrofitError error) { displayError(error); } }; 

Image Loading 

Picasso Hassle-free image downloading and caching Handles ImageView recycling automatically Performs download cancellations automatically Allows complex image transformations Automatic memory and disk caching square.github.io/picasso 

Picasso Usage Picasso.with(context).load("http://i.imgur.com/DvpvklR.png").into(imageView); Picasso.with(context) .load(url) .resize(50, 50) .centerCrop() .placeholder(R.drawable.user_placeholder) .error(R.drawable.user_placeholder_error) .into(imageView) Picasso.with(context).load(R.drawable.landing_screen).into(imageView1); Picasso.with(context).load("file:///android_asset/DvpvklR.png").into(imageView2); Picasso.with(context).load(new File(...)).into(imageView3); 

Microsavings Small things, big benefits 

Timber Logger built on top of android.util.Log Small and extensible API Automatic smart tagging No logging in production, ever! jakewharton.github.io/timber 

Timber Usage public class SherlockApplication extends Application { @Override public void onCreate() { super.onCreate(); if (BuildConfig.DEBUG) { Timber.plant(new Timber.DebugTree()); } else { Timber.plant(new CrashReportingTree()); } } } Timber.i("A button with ID %s was clicked to say '%s'.", button.getId(), button.getText()); Timber.e("Search failed with error: " + error.getKind()); 

Timber Usage private static class CrashReportingTree extends Timber.HollowTree { @Override public void i(String message, Object... args) { // TODO e.g., Crashlytics.log(String.format(message, args)); } @Override public void i(Throwable t, String message, Object... args) { i(message, args); // Just add to the log. } @Override public void e(String message, Object... args) { i("ERROR: " + message, args); // Just add to the log. } @Override public void e(Throwable t, String message, Object... args) { e(message, args); // TODO e.g., Crashlytics.logException(t); } } 

Demo 

Q & A Ask me questions! Code available at - github.com/mustafa01ali/Sherlock 

Thank you! You can reach out to me at @mustafa01ali