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ViewBinding - how to get binding for included layouts?

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How do I convert layout to data binding layout?

To convert your XML layouts into the Data Binding layout, follow the below steps: Declare a <layout> tag, which will wrap your existing layout file at the root level. Declare variables under the <data> tag, which will go under the <layout> tag. Declare necessary expressions to bind data inside the view elements.

How would you enable view binding for a module in your application so you can reference views from layout files without using findViewById?

To enable view binding, configure viewBinding in your module-level build. gradle file. Once enabled for a project, view binding will generate a binding class for all of your layouts automatically. You don't have to make changes to your XML — it'll automatically work with your existing layouts.


In case of:

  1. Include with generic layout (not merge node), we need to assign ID to included part, this way in binding we will have access to included sub part
<include
    android:id="@+id/your_id"
    layout="@layout/some_layout" />

This way in your activity code:

private lateinit var exampleBinding: ActivityExampleBinding  //activity_example.xml layout

override fun onCreate(savedInstanceState: Bundle?) {
    super.onCreate(savedInstanceState)
    exampleBinding = ActivityExampleBinding.inflate(layoutInflater)
    setContentView(exampleBinding.root)
    //we will be able to access included layouts view like this
    val includedView: View = exampleBinding.yourId.idOfIncludedView
//[...]
}
  1. Include with merge block in external layout. We can't add ID to it because merge block is not a view. Let's say we have such eternal merge layout (merge_layout.xm):
<?xml version="1.0" encoding="utf-8"?>
<merge xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    xmlns:tools="http://schemas.android.com/tools"
    tools:showIn="@layout/activity_example">

    <TextView
        android:id="@+id/some_view"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="Hello World" />
</merge>

To properly bind such merge layout we need to:

In your activity code:

private lateinit var exampleBinding: ActivityExampleBinding  //activity_example.xml layout
private lateinit var mergeBinding: MergeLayoutBinding  //merge_layout.xml layout

override fun onCreate(savedInstanceState: Bundle?) {
    super.onCreate(savedInstanceState)
    exampleBinding = ActivityExampleBinding.inflate(layoutInflater)
    //we need to bind the root layout with our binder for external layout
    mergeBinding = MergeLayoutBinding.bind(exampleBinding.root)
    setContentView(exampleBinding.root)
    //we will be able to access included in merge layout views like this
    val mergedView: View = mergeBinding.someView
//[...]
}

Your first question, that is working with an included layout using ViewBinding can be solved so easily.

Here is a sample main_fragment.xml file

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:orientation="vertical">

    <androidx.recyclerview.widget.RecyclerView
        android:id="@+id/recycler_view_main"
        android:layout_width="match_parent"
        android:layout_height="0dp"
        android:layout_weight="1" />

    <include
        android:id="@+id/toolbar"
        layout="@layout/toolbar" />

</LinearLayout>

And MainFragment.java can be like this

public class MeaningFragment extends Fragment {

    private MainFragmentBinding binding;
    private ToolbarBinding toolbarBinding;

    @Nullable
    @Override
    public View onCreateView(@NonNull LayoutInflater inflater, ViewGroup container,
                         Bundle savedInstanceState) {

        binding = MainFragmentBinding.inflate(inflater, container, false);
        toolbarBinding = binding.toolbar;

        return binding.getRoot();
    }

    @Override
    public void onDestroy() {
        super.onDestroy();

        toolbarBinding = null;
        binding = null;
    }
}

Now, you have two bindings. one of them is the default and the next one is from the included layout.


If you want to bind included layout then,

For Activity

YourMainLayoutBinding mainLayoutBinding = MainLayoutBinding.inflate(getLayoutInflater);

View view = mainLayoutBinding.getRoot();

YourIncludedLayoutBinding includedLayoutBinding = YourIncludedLayoutBinding.bind(View);

For Fragment

YourMainLayoutBinding mainLayoutBinding = MainLayoutBinding.inflate(inflater,container,false);

View view = mainLayoutBinding.getRoot();

YourIncludedLayoutBinding includedLayoutBinding = YourIncludedLayoutBinding.bind(View);

Make Sure if your main layout binding parent root is LinearLayout then, includedLayoutBinding parent layout also be a linear layout


Suppose I included a layout in my activity_main.xml file as follows:

<include
    android:id="@+id/ll_layout1"
    layout="@layout/layout1"
    android:visibility="gone" />

And suppose I wanted to change its visibility. I can do so as follows:

activityMainBinding.llLayout1.root.visibility = View.VISIBLE