【Kotlin/Android Studio】DataBindingの方法！findViewByIdを排除する

build.gradle(Module)
android {
  // 〜〜〜〜〜〜

  buildFeatures {
    dataBinding true
  }

  // 〜〜〜〜〜〜
}

Execution failed for task ':app:checkDebugAarMetadata'.
> A failure occurred while executing com.android.build.gradle.internal.tasks.CheckAarMetadataWorkAction
   > 5 issues were found when checking AAR metadata:
  
    1.  Dependency 'androidx.appcompat:appcompat-resources:1.7.0' requires libraries and applications that
      depend on it to compile against version 34 or later of the
      Android APIs.

      :app is currently compiled against android-33.

      Also, the maximum recommended compile SDK version for Android Gradle
      plugin 8.0.2 is 33.

      Recommended action: Update this project's version of the Android Gradle
      plugin to one that supports 34, then update this project to use
      compileSdk of at least 34.

      Note that updating a library or application's compileSdk (which
      allows newer APIs to be used) can be done separately from updating
      targetSdk (which opts the app in to new runtime behavior) and
      minSdk (which determines which devices the app can be installed
      on).

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

    <data>

    </data>

    <androidx.constraintlayout.widget.ConstraintLayout
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        tools:context=".MainActivity">

        <TextView
            android:id="@+id/main_text"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:text="Hello World!"
            app:layout_constraintBottom_toBottomOf="parent"
            app:layout_constraintStart_toStartOf="parent"
            app:layout_constraintEnd_toEndOf="parent"
            app:layout_constraintTop_toTopOf="parent" />


        <Button
            android:id="@+id/done_button"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:text="Button"
            app:layout_constraintBottom_toBottomOf="parent"
            app:layout_constraintEnd_toEndOf="parent"
            app:layout_constraintStart_toStartOf="parent"
            app:layout_constraintTop_toBottomOf="@+id/main_text" />

    </androidx.constraintlayout.widget.ConstraintLayout>
</layout>

MainActivity.kt
private lateinit var binding: ActivityMainBinding

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

MainActivity.kt
binding.doneButton.setOnClickListener{
  binding.mainText.setText("こんにちは")
}

class FirstFragment : Fragment() {

    private var _binding: FragmentFirstBinding? = null
    private val binding get() = _binding!!

    override fun onCreateView(
        inflater: LayoutInflater, container: ViewGroup?,
        savedInstanceState: Bundle?
    ): View? {
        _binding = FragmentFirstBinding.inflate(inflater, container, false)
        binding.lifecycleOwner = viewLifecycleOwner
        return binding.root
    }

    override fun onViewCreated(view: View, savedInstanceState: Bundle?) {
        super.onViewCreated(view, savedInstanceState)

        binding.doneButton.setOnClickListener {
            parentFragmentManager.popBackStack()
        }
    }

    override fun onDestroyView() {
        super.onDestroyView()
        _binding = null
    }
}

class FirstFragment : Fragment() {

    private lateinit var binding: FragmentFirstBinding

    override fun onCreateView(
        inflater: LayoutInflater, container: ViewGroup?,
        savedInstanceState: Bundle?
    ): View? {
        binding = FragmentFirstBinding.inflate(inflater, container, false)
        binding.lifecycleOwner = viewLifecycleOwner
        return binding.root
    }
}

User.kt
data class User(
  var name: String = "", 
  var nickname: String = ""
)

activity_main.xml
<data>
    <variable name="user" type="com.example.databinding.User" />
</data>

activity_main.xml
<TextView
    android:id="@+id/main_text"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
+   android:text="@{user.name}"
    app:layout_constraintBottom_toBottomOf="parent"
    app:layout_constraintStart_toStartOf="parent"
    app:layout_constraintEnd_toEndOf="parent"
    app:layout_constraintTop_toTopOf="parent" />

MainActivity.kt
binding.user = User("ame")

activity_main.xml
<EditText
  android:id="@+id/edit_nickname"
  android:layout_width="wrap_content"
  android:layout_height="wrap_content"
  android:ems="10"
  android:inputType="text"
  android:text="nickname"
  app:layout_constraintBottom_toTopOf="@+id/main_text"
  app:layout_constraintEnd_toEndOf="parent"
  app:layout_constraintStart_toStartOf="parent"
  app:layout_constraintTop_toTopOf="parent" />

  <TextView
      android:id="@+id/textView"
      android:layout_width="wrap_content"
      android:layout_height="wrap_content"
      android:text="@={user.nickname}"
      app:layout_constraintBottom_toTopOf="@+id/main_text"
      app:layout_constraintEnd_toEndOf="parent"
      app:layout_constraintStart_toStartOf="parent"
      app:layout_constraintTop_toBottomOf="@+id/edit_nickname" />

MainActivity.kt
binding.apply {
    doneButton.setOnClickListener{
        user?.nickname = editNickname.text.toString()
        invalidateAll()
    }
}

android:text="@{user.nickname, default=ニックネーム}"

xmlレイアウト
<data>
    <import type="java.util.Map"/>
    <import type="java.util.List"/>
    <variable name="list" type="List&lt;String>"/>
    <variable name="map" type="Map&lt;String, String>"/>
</data>

xmlレイアウト
android:text="@{list[0]}"
android:text="@{map[`name`]}"

binding.list = listOf("1", "2")
binding.map = mapOf("name" to "ame", "age" to "29")

xmlレイアウト
android:text="@{list[3] != null ? list[3] : `none`}"
-- または--
android:text="@{list[3] ?? `none`}"

android:text="@{String.valueOf(index + 1)}"
android:visibility="@{age > 13 ? View.GONE : View.VISIBLE}"
android:transitionName='@{"image_" + id}'