– Dead Poet’s Society “No matter what anybody tells you words and ideas can change the world.” 

What is a Language? 1. First we listen, then speak and then we write. 2. We learn from structures. 3. Every word has a context. 4. Vocabulary and knowledge makes you express better. 5. The more we read, the more we learn the language. 

What is a Computer Language? 1. First we listen, then speak and then we write. 2. We learn from structures. 3. Every word has a context. 4. Vocabulary and knowledge makes you express better. 5. The more we read, the more we learn the language. 

Eloquence Fluent or persuasive speaking or writing. 

Brevity Concise and exact use of words in writing or speech. 

Boil Boilerplate Code With Data Binding 

What? 1. Software Pattern to simplify UI development. 2. Binds UI elements to an App Domain Model. 3. Minimizes the glue code. 4. Incorporates Observer pattern. 5. Flexibility and broad compatibility (API level 7+). 6. Short and readable code. 

What? 

Why? private TextView name; private TextView age; protected void onCreate(Bundle savedInstanceState) { setContentView(R.layout.activity_main); name = (TextView) findViewById(R.id.name); age = (TextView) findViewById(R.id.age); } public void updateUI(User user) { if (user == null) { name.setText(null); age.setText(null); } else { name.setText(user.getName()); mLastName.setText(user.getLastName()); } } INSIPID BOILERPLATE BLOATED CLASSES REDUNDANT 

Why? private @BindView(R.id.name) TextView name; private @BindView(R.id.age) TextView age; protected void onCreate(Bundle savedInstanceState) { setContentView(R.layout.activity_main); ButterKnife.bind(this); } public void updateUI(User user) { if (user == null) { name.setText(null); age.setText(null); } else { name.setText(user.getName()); mLastName.setText(user.getLastName()); } } Use Holdr? Use Butterknife? 

Let’s boil the code! Boiler -plate Code Data Binding 

Data Bound Code private ActivityMainBinding binding; protected void onCreate(Bundle savedInstanceState) { binding = DataBindingUtil.setContentView(this, R.layout.activity_main); } public void updateUI(User user) { binding.setUser(user); } Moustache Operator Generated Class View Model Layout Tag 

How? android { .... dataBinding { enabled = true } } In your app-level build.gradle // For Activity binding = DataBindingUtil.setContentView(this, R.layout.layout); // For Fragment binding = DataBindingUtil.inflate(inflater, R.layout.layout, container, false); // For ViewHolder binding = DataBindingUtil.bind(view); In your View 

Model View ViewModel Model View 

Model View ViewModel 

public class LoginModel extends BaseObservable { private String email; private String password; @Bindable public String getEmail() { return email; } public void setEmail(String email) { this.email = email; notifyPropertyChanged(BR.email); } @Bindable public String getPassword() { return password; } public void setPassword(String password) { this.password = password; notifyPropertyChanged(BR.password); } } View Model Java 

View Model Kotlin public class LoginModel : BaseObservable() { @get:Bindable var email: String? = null set(email) { field = email notifyPropertyChanged(BR.email) } @get:Bindable var password: String? = null set(password) { field = password notifyPropertyChanged(BR.password) } } 

public class LoginModel { public final ObservableField email = new ObservableField<>(); public final ObservableField password = new ObservableField<>(); public String getEmail() { return email.get(); } public String getPassword() { return password.get(); } public void setEmail(String email) { this.email.set(email); } public void setPassword(String password) { this.password.set(password); } } ObservableField<> 

public class LoginModel implements Observable { public String email; public String password; private PropertyChangeRegistry registry = new PropertyChangeRegistry(); @Bindable public String getEmail() { return email; } public void setEmail(String email) { this.email = email; registry.notifyChange(this, BR.email); setLoginEnabled(isEmailAndPasswordSet()); } … @Override public void addOnPropertyChangedCallback(OnPropertyChangedCallback callback) { registry.add(callback); } @Override public void removeOnPropertyChangedCallback(OnPropertyChangedCallback callback) { registry.remove(callback); } } PropertyChangeRegistry 

Login User enters email and password and taps Login 

Event Handling

Event Handling public class MainActivity extends AppCompatActivity implements MainHandler { private ActivityMainBinding binding; private LoginModel model = new LoginModel(); @Override protected void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); binding = DataBindingUtil.setContentView(this, R.layout.activity_main); binding.setModel(model); binding.setHandler(this); } @Override public void onLoginClicked(String email, String password) { Toast.makeText(this, "Email: " + email + "\nPassword: " + password, Toast.LENGTH_SHORT).show(); } } 

Event Handling public class Presenter { public void onCompletedChanged(Task task, boolean completed){} } 

Two Way binding 2-way binding (Moustache with a nose) 

public class LoginModel extends BaseObservable { private String email; private String password; private boolean loginEnabled; @Bindable public String getEmail() { return email; } public void setEmail(String email) { this.email = email; notifyPropertyChanged(BR.email); setLoginEnabled(isEmailAndPasswordSet()); } … private boolean isEmailAndPasswordSet() { return !TextUtils.isEmpty(getEmail()) && !TextUtils.isEmpty(getPassword()); } } Validations Good bye Text watchers " 

Resources In Expressions: android:padding="@{isBig ? @dimen/bigPadding : @dimen/smallPadding}" Inline string formatting: android:text="@{@string/nameFormat(firstName, lastName)}" Inline plurals: android:text="@{@plurals/banana(bananaCount)}" 

Null Safety UI won’t crash if user is null. @{user.card.number, default=@string/no_number} @{user.card.number ?? @string/no_number} Use Null Coalescing 

RecyclerView Binding public class UserViewHolder extends RecyclerView.ViewHolder { static UserViewHolder create(LayoutInflater inflater, ViewGroup parent) { UserItemBinding binding = UserItemBinding.inflate(inflater, parent, false); return new UserViewHolder(binding); } private UserItemBinding mBinding; private UserViewHolder(UserItemBinding binding) { super(binding.getRoot()); mBinding = binding; } public void bindTo(User user) { mBinding.setUser(user); mBinding.executePendingBindings(); } } 

RecyclerView Binding public UserViewHolder onCreateViewHolder(ViewGroup viewGroup, int i) { return UserViewHolder.create(mLayoutInflater, viewGroup); } public void onBindViewHolder(UserViewHolder userViewHolder, int position) { userViewHolder.bindTo(mUserList.get(position)); } 



Custom View Inflation public class CustomView extends LinearLayout implements CustomViewHandler { private LayoutCustomViewBinding binding; private CustomViewModel model = new CustomViewModel() public CustomView(Context context) { this(context, null); } public CustomView(Context context, @Nullable AttributeSet attrs) { this(context, attrs, 0); } public CustomView(Context context, @Nullable AttributeSet attrs, int defStyleAttr) { super(context, attrs, defStyleAttr); init(context); } @Override public void init(Context context) { final LayoutInflater inflater = (LayoutInflater) context.getSystemService(Context.LAYOUT_INFLATER_SERVICE); binding = LayoutCustomViewBinding.inflate(inflater, this, true); binding.setModel(model); binding.setHandler(this); } @Override public void onCustomViewClicked() { Toast.makeText(this, “Hello", Toast.LENGTH_SHORT).show(); } } 

Binding Adapter @BindingAdapter({"app:src", "app:error"}) public static void loadImage(ImageView view, String srcUrl, Drawable error) { Glide.with(view.getContext()) .load(srcUrl) .error(error) .into(view); } @BindingAdapter(value = {“app:src", "app:error"}, requireAll = false) Has to be static 

Binding Conversions @BindingConversion public static int convertBooleanToVisibility(boolean visible) { return visible ? View.VISIBLE : View.GONE; } Great use case for Empty/Placeholder Views … 

Binding Fonts // In Application class FontCache fontCache = FontCache.getInstance(this); fontCache.addFont("droid", "DroidSerif.ttf"); // In BindingAdapter @BindingAdapter({"app:font"}) public static void setFont(TextView textView, String fontName) { textView .setTypeface(FontCache.getInstance(context) .get(fontName)); } // In Layout 

Dependency Injection public interface TestableAdapter { @BindingAdapter("android:src") void setImageUrl(ImageView imageView, String url); } public interface DataBindingComponent { TestableAdapter getTestableAdapter(); } DataBindingUtil.setDefaultComponent(myComponent); ‐ or ‐ binding = MyLayoutBinding.inflate(layoutInflater, myComponent); In Activity In Application 

Daggerification // Create BindingComponent @Singleton public class BindingComponent implements DataBindingComponent { BindingAdapter bindingAdapter; @Inject public BindingComponent() { } public BindingAdapter getBindingAdapter() { return bindingAdapter; } } // Create getter of BindingComponent AppComponent @Singleton @Component(modules = {AppModule.class}) public interface AppComponent { void inject(MyApplication myApplication); BindingComponent getBindingComponent(); } // Set DefaultComponent in Application class DataBindingUtil.setDefaultComponent(component.getBindingComponent()); 

Rxification compile 'com.jakewharton.rxbinding2:rxbinding:2.0.0' Button b = (Button)findViewById(R.id.button); Subscription buttonSub = RxView.clicks(b).subscribe(new Action1() { @Override public void call(Void aVoid) { // do some work here } }); RxBinding is a set of libraries that allow you to react to user interface events via the RxJava paradigm. 

Search using RxBinding RxTextView.textChanges(searchTextView) .filter(new Func1 (){ @Override public Boolean call(String s) { return s.length() > 2; } }) .debounce(100, TimeUnit.MILLISECONDS) .switchMap(new Func1>>() { makeApiCall(s); }) .subscribeOn(Schedulers.io()) .observeOn(AndroidSchedulers.mainThread()) .subscribe(/* attach observer */); 

Tools DataBinding Support Plugin Alt + Enter 

References 1. https://academy.realm.io/posts/data-binding-android-boyar-mount/ 2. https://academy.realm.io/posts/droidkaigi-kevin-pelgrims-data-real-world- data-binding/ 3. https://nullpointer.wtf/android/mvvm-architecture-data-binding-library/ 4. https://medium.com/@chet.deva/boil-boilerplate-code-with-data-binding- bb0ed0d0ceb6 

Thank you Chetan Sachdeva Android Dev at Fueled @chetsachdeva