Part 1 – Setup & Simple Binding

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In this video series, we will learn how to use the Data Binding library from the Android Architecture Components.
In part 1, we will enable Data Binding which is bundled with the Android Gradle Plugin in our Android Studio project, add the Kotlin annotation processor kapt plugin and write our first XML binding expressions.
I will also give a comparison between Data Binding and it’s other alternatives, namely View Binding, findViewById, and Kotlin’s synthetic properties.

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activity_main.xmlMainActivity.ktUser.kt

<?xml version="1.0" encoding="utf-8"?>
<layout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools">

    <data>

        <variable
            name="user"
            type="com.codinginflow.databindingexample.User" />
    </data>

    <LinearLayout
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        android:gravity="center"
        android:orientation="vertical"
        tools:context=".MainActivity">

        <TextView
            android:id="@+id/text_view_first_name"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:text="@{user.firstName}"
            android:textAppearance="@style/TextAppearance.AppCompat.Large" />

        <TextView
            android:id="@+id/text_view_last_name"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:text="@{user.lastName}"
            android:textAppearance="@style/TextAppearance.AppCompat.Large" />

        <TextView
            android:id="@+id/text_view_age"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:text="@{String.valueOf(user.age)}"
            android:textAppearance="@style/TextAppearance.AppCompat.Large" />

    </LinearLayout>
</layout>

package com.codinginflow.databindingexample

import androidx.appcompat.app.AppCompatActivity
import android.os.Bundle
import androidx.databinding.DataBindingUtil
import com.codinginflow.databindingexample.databinding.ActivityMainBinding

class MainActivity : AppCompatActivity() {

    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)
        val binding: ActivityMainBinding =
            DataBindingUtil.setContentView(this, R.layout.activity_main)

        binding.user = User("Florian", "Walther", 29)
    }
}

package com.codinginflow.databindingexample

data class User(val firstName: String, val lastName: String, val age: Int)