android - Include layout with custom attributes

Question

I'm building a complex layout and I want to use include tag for my custom component, like this:

<include layout="@layout/topbar"/>

The topbar layout has custom root component and in layout xml file it's defined like this:

<my.package.TopBarLayout
 ... a lot of code

Now, I wanna pass my custom defined attributes to "topbar" like this:

<include layout="@layout/topbar" txt:trName="@string/contacts"/>

And then get the value of those custom attributes in custom component code or ideally in xml.

Sadly, I cannot get value of txt:trName attribute to make it to the topbar layout, I just don't receive anything in code. If I understand correctly from that documentation page, I can set no attributes for layouts used via include, but id, height and width.

So my question is how can I pass my custom defined attributes to layout which is added via include?

Answer 1

I know this is an old question but I came across it and found that it is now possible thanks to Data Binding.

First you need to enable Data Binding in your project. Use DataBindingUtil.inflate (instead of setContentView, if it's Activity) to make it work.

Then add data binding to the layout you want to include:

<?xml version="1.0" encoding="utf-8"?>    
<layout xmlns:android="http://schemas.android.com/apk/res/android">
    <data>
        <variable name="title" type="java.lang.String"/>
    </data>
    <RelativeLayout xmlns:app="http://schemas.android.com/apk/res-auto"
        android:id="@+id/screen_header"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:layout_gravity="top"
        android:gravity="center">

    ...

        <TextView
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:layout_centerInParent="true"
            android:textSize="20sp"
            android:textStyle="bold"
            android:text="@{title}"/>

    ...

    </RelativeLayout>
</layout>

Finally, pass the variable from the main layout to the included layout like this:

<?xml version="1.0" encoding="utf-8"?>
<layout xmlns:android="http://schemas.android.com/apk/res/android"
        xmlns:app="http://schemas.android.com/apk/res-auto">
    <data>
        ...
    </data>
    ...
    <include layout="@layout/included_layout"
        android:id="@+id/title"
        app:title="@{@string/title}"/>
    ...
</layout>