Linking UI layer with Data Model-Part -1

The Data Binding — Support library that facilitate you to bind layout’s UI components to data models directly in the layout itself rather than programmatically.

It means :

How does it help ?

      1.  Reduce boilerplate code in java files.

      2.  Increase readability in java files.

Disadvantages :

       1.  Creates additional autogenerated classes which is overhead on apk size.    

       2.  Difficult to debug as code will be scattered in the java as well as xml file.

Steps to do data binding :

1.Add these lines in app build.gradle

// enable data binding for the application
android {
    ......
    dataBinding {
        enabled = true
    }
}

2. Add layouts and binding expressions in the layout activity_main.xml

<layout xmlns:android="http://schemas.android.com/apk/res/android"
        xmlns:app="http://schemas.android.com/apk/res-auto">
    <data>
        <variable
            name="user"
            type="com.codehangouts.databindingdemo.User" />
    </data>
    <ConstraintLayout... /> <!-- UI layout's root element -->
</layout>

3. User the model reference in the layout xml wherever required.

<TextView
   android:layout_width="wrap_content"
   android:layout_height="wrap_content
   android:text="@{user.name}" />

4. Binding data with Activity or Fragment

In case of Activity

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
   //ActivityMainBinding will be autogenerated if activity_main
  // is the layout name 
  ActivityMainBinding userBinding=DataBindingUtil. setContentView(this,R.layout.activity_main);
  User  user = …..// get or create the User object
  ....
  ....
  userBinding.setUser(user);
}

In case of Fragment:

@Override    
public View onCreateView(LayoutInflater inflater, ViewGroup     container,Bundle savedInstanceState) {
   //FragmentDataBinding will be autogenerated if fragment_main
   // is the layout name
   FragmentMainBinding userBinding     =        
   DataBindingUtil. inflate(inflater,R.layout.fragment_main, 
   container,  false);
    ... 
    View rootView = userBinding.getRoot();
    ...
    ...
    User  user = …..// get or create the user object    
    user.setUser(user);
    ....
    ....
    return rootView}

Conclusion

This is just the overview of Android data binding, however a lot more interesting and powerful features are available in the library which will be covered in the next part.

Find the article on my  Medium Blog as well.