How to use <layout> tag in Android

Question

I need to know how to use layout tag in android xml file. I know it is used for data binding but I do not have complete knowledge on this. Please let me know if anyone can help me in same.

Thanks in Advance !!

Answer 1

The <layout> tag must be the root tag when you are using DataBinding. Doing so you are telling the compiler that you are using DataBinding and your layout will have special tags like <variable> or <import>, so you have to embed your layout within that tag.

In short, you need to use the <layout> tag whenever you are using DataBinding for the compiler to understand the special tags and generate the DataBinding class with the right variables and methods.

If you have a layout like this (layout_data_binding.xml):

<layout xmlns:android="http://schemas.android.com/apk/res/android">
   <data>
       <variable name="user" type="com.example.User"/>
   </data>
   <LinearLayout
       android:orientation="vertical"
       android:layout_width="match_parent"
       android:layout_height="match_parent">
       <TextView android:layout_width="wrap_content"
           android:layout_height="wrap_content"
           android:text="@{user.firstName}"/>
       <TextView android:layout_width="wrap_content"
           android:layout_height="wrap_content"
           android:text="@{user.lastName}"/>
   </LinearLayout>
</layout>

It is based on what is inside the <layout> tag to create the LayoutDataBinding class (auto-generated) with the User variable and its getters and setters.