ViewBinding – how to get binding for included layouts?

While working with ViewBinding I come across few not documented cases.

First: How to get binding for included generic view layout parts, main binding see only items in main layout?

Second: How to get binding for included merge type layout parts, again main binding see only items in main layout?

Answer

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
//[...]
}

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