Include layouts

If creating multiple instances of the same layout it is good practice to save that layout code in its own file and instantiate it using the tag e.g. you are designing separate portrait and landscape layouts of the same content with groups of objects such as those in a table which will remain in an identical relative layout across both designs.

Given this original layout:
<?xml version="1.0" encoding="utf-8"?>
<layout>
<ScrollView xmlns:app="http://schemas.android.com/apk/res-auto"
    xmlns:tools="http://schemas.android.com/tools"
    xmlns:android="http://schemas.android.com/apk/res/android"
    android:id="@+id/scroll"
    android:layout_width="match_parent"
    android:layout_height="wrap_content">

    <android.support.constraint.ConstraintLayout
        android:orientation="vertical"
        android:layout_width="match_parent"
        android:layout_height="match_parent">

        <TextView
            android:text="@string/passenger_label"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            ... />

        <TextView
            tools:text="@string/passenger_name"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            ... />

<!-- Start of section of code defining a group of objects in a fixed layout to be duplicated across portrait and landscape -->

        <ImageView
            android:id="@+id/leftRectangle"
            android:layout_width="60dp"
            android:layout_height="80dp"
            ... />

        <ImageView
            android:id="@+id/divider"
            android:background="@color/colorPrimaryLight"
            ... />

        <ImageView
            android:id="@+id/rightRectangle"
            android:layout_width="60dp"
            android:layout_height="80dp"
            ... />

        <TextView
            android:id="@+id/textViewOriginAirport"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            ... />

        <TextView
            android:id="@+id/textViewDestinationAirport"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            ... />

        <ImageView
            android:id="@+id/imagePlane"
            android:layout_height="wrap_content"
            android:layout_width="wrap_content"
            ... />

        <TextView
            android:id="@+id/textViewFlightCode"
            tools:text="@string/flight_code"
            android:layout_width="wrap_content"
            ... />

<!-- Endof section of code defining a group of objects -->

        <TextView
            android:id="@+id/textViewBoardingTimeLabel"
            android:text="@string/boarding_time_label"
            android:layout_width="wrap_content"
            ... />

        <TextView
            android:id="@+id/textViewBoardingTime"
            tools:text="@string/boarding_time"
            android:layout_width="wrap_content"
            ... />

        <TextView
            android:id="@+id/textViewDepartureTimeLabel"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            ... />

        <TextView
            android:id="@+id/textViewDepartureTime"
            tools:text="@string/departure_time"
            android:layout_width="wrap_content"
            ... />

    </android.support.constraint.ConstraintLayout>
</ScrollView>
</layout>

The extracted code pasted into it separate layout file (name boarding_info.xml) would look like:
<?xml version="1.0" encoding="utf-8"?>
<layout xmlns:android="http://schemas.android.com/apk/res/android" // Very important to include these tags
    xmlns:app="http://schemas.android.com/apk/res-auto"
    xmlns:tools="http://schemas.android.com/tools">

    <android.support.constraint.ConstraintLayout // Very important to include these tags
        android:layout_width="match_parent"
        android:layout_height="match_parent">

        <ImageView
            android:id="@+id/leftRectangle"
            android:layout_width="60dp"
            android:layout_height="80dp"
            ... />

        <ImageView
            android:id="@+id/divider"
            android:background="@color/colorPrimaryLight"
            ... />

        <ImageView
            android:id="@+id/rightRectangle"
            android:layout_width="60dp"
            android:layout_height="80dp"
            ... />

        <TextView
            android:id="@+id/textViewOriginAirport"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            ... />

        <TextView
            android:id="@+id/textViewDestinationAirport"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            ... />

        <ImageView
            android:id="@+id/imagePlane"
            android:layout_height="wrap_content"
            android:layout_width="wrap_content"
            ... />

        <TextView
            android:id="@+id/textViewFlightCode"
            tools:text="@string/flight_code"
            android:layout_width="wrap_content"
            ... />

    </android.support.constraint.ConstraintLayout>

</layout>

And the original file would look like:
<layout>
<ScrollView xmlns:app="http://schemas.android.com/apk/res-auto"
    xmlns:tools="http://schemas.android.com/tools"
    xmlns:android="http://schemas.android.com/apk/res/android"
    android:id="@+id/scroll"
    android:layout_width="match_parent"
    android:layout_height="wrap_content">

    <android.support.constraint.ConstraintLayout
        android:orientation="vertical"
        android:layout_width="match_parent"
        android:layout_height="match_parent">

        <TextView
            android:text="@string/passenger_label"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            ... />

        <TextView
            tools:text="@string/passenger_name"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            ... />

        <include
            android:id="@+id/boarding_info" // Essential for binding data
            layout="@layout/boarding_info" // Only essential attribute - others added on on aligning with surrounding elements
            android:layout_width="0dp"
            android:layout_height="wrap_content"
            ... />

        <TextView
            android:id="@+id/textViewBoardingTimeLabel"
            android:text="@string/boarding_time_label"
            android:layout_width="wrap_content"
            ... />

        <TextView
            android:id="@+id/textViewBoardingTime"
            tools:text="@string/boarding_time"
            android:layout_width="wrap_content"
            ... />

        <TextView
            android:id="@+id/textViewDepartureTimeLabel"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            ... />

        <TextView
            android:id="@+id/textViewDepartureTime"
            tools:text="@string/departure_time"
            android:layout_width="wrap_content"
            ... />

    </android.support.constraint.ConstraintLayout>
</ScrollView>
</layout>

If binding to these layouts you will need to add in an extra reference to the include file e.g.
mBinding.textViewOriginAirport.setText("aString");
becomes
mBinding.boardingInfo.textViewOriginAirport.setText("aString"); // boardingInfo automatically generated from 'boarding_info' xml name