Android Studio can't find classes for MotionLayout

Question

I'm trying to use android MotionLayout, but it can't find appropriate classes for it and wont work.

I tried implementing the below dependencies:

implementation 'androidx.constraintlayout:constraintlayout:2.0.0-beta2'
implementation 'androidx.constraintlayout:constraintlayout:2.0.0-beta1'
implementation 'com.android.support.constraint:constraint-layout:2.0.0-beta1'
implementation 'com.android.support.constraint:constraint-layout:2.0.0-alpha2'
implementation 'com.android.support.constraint:constraint-layout:2.0.0-alpha4'

but none of them seems to work...

here is my XML file:

<android.support.constraint.motion.MotionLayout
xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:app="http://schemas.android.com/apk/res-auto"
footstools="http://schemas.android.com/tools"
android:id="@+id/motionLayout"
android:layout_width="match_parent"
android:layout_height="match_parent"
tools:showPaths="true"
tools:context=".PlayGameActivity">

<View
    android:id="@+id/button"
    android:layout_width="64dp"
    android:layout_height="64dp"
    android:background="@color/colorAccent"
    android:text="Button" />

</android.support.constraint.motion.MotionLayout >'

but it gives me always this error massage:

Missing classes
The following classes could not be found:
- android.support.constraint.motion.MotionLayout (Fix Build Path, Edit XML, Create Class)
Tip: Try to build the project.   
Tip: Try to refresh the layout.

and in the preview window of the projects it fills the entire layout in gray and writes in the center:

android...MotionLayout

Answer 1

There is no android.support.constraint.motion.MotionLayout

in implementation "androidx.constraintlayout:constraintlayout:2.0.0-beta2".

It's called androidx.constraintlayout.motion.widget.MotionLayout.

If MotionLayout shows up gray, you might be lacking the app:layoutDescription XML.

There's an example for AndroidX & Support Library versions.