[Android] Two ways Binding

android {
...
    buildFeatures {
       dataBinding true
    }
}

<?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"
    xmlns:tools="http://schemas.android.com/tools">

    <data>

    </data>

    <LinearLayout
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        tools:context=".MainActivity">

        <TextView
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            app:layout_constraintBottom_toBottomOf="parent"
            app:layout_constraintLeft_toLeftOf="parent"
            app:layout_constraintRight_toRightOf="parent"
            app:layout_constraintTop_toTopOf="parent" />

    </LinearLayout>
</layout>

  val binding: ActivityMainBinding =
            DataBindingUtil.setContentView(this, R.layout.activity_main)

class MainViewModel : ViewModel()

  <data>
        <variable
            name="viewmodel"
            type="com.molysulfur.example.databinding.MainViewModel" />
  </data>

class MainViewModel : ViewModel() {

    private val _numbers: MutableLiveData<Int> = MutableLiveData(0)

    var number : Int = 0
    val numbers: LiveData<Int> = _numbers

    fun onClick() {
        _numbers.value = (_numbers.value ?: 0) + 1
    }

}

<?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"
    xmlns:tools="http://schemas.android.com/tools">

    <data>

        <variable
            name="viewmodel"
            type="com.molysulfur.example.databinding.MainViewModel" />
    </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/main_name"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:text="@{viewmodel.numbers.toString()}"
            app:layout_constraintBottom_toBottomOf="parent"
            app:layout_constraintLeft_toLeftOf="parent"
            app:layout_constraintRight_toRightOf="parent"
            app:layout_constraintTop_toTopOf="parent" />

        <Button
            android:id="@+id/main_button"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:onClick="@{() -> viewmodel.onClick()}"
            android:text="Click" />
    </LinearLayout>
</layout>

object BindingAdapters {

    @BindingAdapter("app:hideIsTen")
    @JvmStatic
    fun hideIsTen(view: View, number: Int) {
        view.visibility = if (number == 10) View.GONE else View.VISIBLE
    }
    
}