Updated libraries so it works today...

app/build.gradle

@@ -1,33 +1,22 @@
-apply plugin: 'com.android.application'
-
-apply plugin: 'kotlin-android'
-
-apply plugin: 'kotlin-android-extensions'
+plugins {
+    id "com.android.application"
+    id "kotlin-android"
+}
 
 android {
-    compileSdkVersion 26
+    compileSdkVersion 33
     defaultConfig {
         applicationId "com.lpirro.constraintlayoutanimations"
         minSdkVersion 21
-        targetSdkVersion 26
+        targetSdkVersion 33
         versionCode 1
         versionName "1.0"
-        testInstrumentationRunner "android.support.test.runner.AndroidJUnitRunner"
-    }
-    buildTypes {
-        release {
-            minifyEnabled false
-            proguardFiles getDefaultProguardFile('proguard-android.txt'), 'proguard-rules.pro'
-        }
+        testInstrumentationRunner "androidx.test.runner.AndroidJUnitRunner"
     }
 }
 
 dependencies {
-    implementation fileTree(dir: 'libs', include: ['*.jar'])
-    implementation"org.jetbrains.kotlin:kotlin-stdlib-jre7:$kotlin_version"
-    implementation 'com.android.support:appcompat-v7:26.1.0'
-    implementation 'com.android.support.constraint:constraint-layout:1.0.2'
-    testImplementation 'junit:junit:4.12'
-    androidTestImplementation 'com.android.support.test:runner:1.0.1'
-    androidTestImplementation 'com.android.support.test.espresso:espresso-core:3.0.1'
+    implementation "org.jetbrains.kotlin:kotlin-stdlib:1.7.20"
+    implementation "androidx.appcompat:appcompat:1.5.1"
+    implementation "androidx.constraintlayout:constraintlayout:2.1.4"
 }

app/src/main/AndroidManifest.xml

@@ -9,7 +9,8 @@
         android:roundIcon="@mipmap/ic_launcher_round"
         android:supportsRtl="true"
         android:theme="@style/AppTheme">
-        <activity android:name=".MainActivity">
+        <activity android:name=".MainActivity"
+            android:exported="true">
             <intent-filter>
                 <action android:name="android.intent.action.MAIN" />
 

app/src/main/java/com/lpirro/constraintlayoutanimations/MainActivity.kt

@@ -1,54 +1,43 @@
 package com.lpirro.constraintlayoutanimations
 
 import android.os.Bundle
-import android.support.constraint.ConstraintSet
-import android.support.v7.app.AppCompatActivity
 import android.transition.ChangeBounds
 import android.transition.TransitionManager
+import android.view.View
 import android.view.animation.AnticipateOvershootInterpolator
-import kotlinx.android.synthetic.main.circuit.*
+import androidx.annotation.LayoutRes
+import androidx.appcompat.app.AppCompatActivity
+import androidx.constraintlayout.widget.ConstraintLayout
+import androidx.constraintlayout.widget.ConstraintSet
 
 class MainActivity : AppCompatActivity() {
 
     private var show = false
+    lateinit var constraintLayout: ConstraintLayout
 
     override fun onCreate(savedInstanceState: Bundle?) {
         super.onCreate(savedInstanceState)
         setContentView(R.layout.circuit)
 
+        constraintLayout = findViewById(R.id.constraint)
+
+        val backgroundImage = findViewById<View>(R.id.backgroundImage)
         backgroundImage.setOnClickListener {
-            if(show)
-                hideComponents() // if the animation is shown, we hide back the views
-            else
-                showComponents() // if the animation is NOT shown, we animate the views
+            show = !show
+            if (show) changeConstraints(R.layout.circuit_detail) // if the animation is NOT shown, we animate the views
+            else changeConstraints(R.layout.circuit) // if the animation is shown, we hide back the views
         }
     }
 
-    private fun showComponents(){
-        show = true
-
-        val constraintSet = ConstraintSet()
-        constraintSet.clone(this, R.layout.circuit_detail)
-
-        val transition = ChangeBounds()
-        transition.interpolator = AnticipateOvershootInterpolator(1.0f)
-        transition.duration = 1200
-
-        TransitionManager.beginDelayedTransition(constraint, transition)
-        constraintSet.applyTo(constraint) //here constraint is the name of view to which we are applying the constraintSet
-    }
-
-    private fun hideComponents(){
-        show = false
-
+    private fun changeConstraints(@LayoutRes newConstraintLayout: Int) {
         val constraintSet = ConstraintSet()
-        constraintSet.clone(this, R.layout.circuit)
+        constraintSet.clone(this, newConstraintLayout)
 
         val transition = ChangeBounds()
         transition.interpolator = AnticipateOvershootInterpolator(1.0f)
         transition.duration = 1200
 
-        TransitionManager.beginDelayedTransition(constraint, transition)
-        constraintSet.applyTo(constraint)  //here constraint is the name of view to which we are applying the constraintSet
+        TransitionManager.beginDelayedTransition(constraintLayout, transition)
+        constraintSet.applyTo(constraintLayout)  //here constraint is the name of view to which we are applying the constraintSet
     }
 }

app/src/main/res/layout/circuit.xml

@@ -1,5 +1,5 @@
 <?xml version="1.0" encoding="utf-8"?>
-<android.support.constraint.ConstraintLayout
+<androidx.constraintlayout.widget.ConstraintLayout
     android:id="@+id/constraint"
     xmlns:android="http://schemas.android.com/apk/res/android"
     xmlns:app="http://schemas.android.com/apk/res-auto"
@@ -21,6 +21,7 @@
         app:layout_constraintTop_toTopOf="parent"/>
 
     <TextView
+        android:id="@+id/t1"
         android:layout_width="wrap_content"
         android:layout_height="wrap_content"
         android:text="JUNE 3, 2018"
@@ -51,7 +52,7 @@
 
     <View
         android:id="@+id/fadeBackgroudView"
-        android:layout_width="wrap_content"
+        android:layout_width="match_parent"
         android:layout_height="90dp"
         android:foreground="@drawable/gradient_variant"
         app:layout_constraintBottom_toTopOf="@+id/description" />
@@ -86,4 +87,4 @@
         app:layout_constraintLeft_toLeftOf="parent"
         app:layout_constraintRight_toRightOf="parent"/>
 
-</android.support.constraint.ConstraintLayout>
+</androidx.constraintlayout.widget.ConstraintLayout>

app/src/main/res/layout/circuit_detail.xml

@@ -1,7 +1,8 @@
 <?xml version="1.0" encoding="utf-8"?>
-<android.support.constraint.ConstraintLayout xmlns:android="http://schemas.android.com/apk/res/android"
+<androidx.constraintlayout.widget.ConstraintLayout 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"
+    android:id="@+id/root"
     android:layout_width="match_parent"
     android:layout_height="match_parent"
     tools:context=".MainActivity">
@@ -23,46 +24,40 @@
         android:layout_height="wrap_content"
         android:layout_marginTop="48dp"
         android:background="#F44336"
-        android:paddingBottom="8dp"
-        android:paddingEnd="24dp"
         android:paddingStart="24dp"
         android:paddingTop="8dp"
+        android:paddingEnd="24dp"
+        android:paddingBottom="8dp"
         android:text="Mugello Circuit"
         android:textColor="#FFFF"
         android:textSize="45sp"
         app:layout_constraintLeft_toLeftOf="parent"
         app:layout_constraintTop_toTopOf="parent" />
 
     <TextView
+        android:id="@+id/t1"
         android:layout_width="wrap_content"
         android:layout_height="wrap_content"
-        android:text="JUNE 3, 2018"
-        app:layout_constraintRight_toRightOf="@+id/title"
-        app:layout_constraintTop_toBottomOf="@+id/title"
-        android:textSize="12sp"
         android:background="#d3d3d3"
         android:paddingStart="16dp"
-        android:paddingEnd="16dp"
         android:paddingTop="3dp"
-        android:paddingBottom="3dp"/>
-
-    <View
-        android:id="@+id/fadeBackgroudView"
-        android:layout_width="wrap_content"
-        android:layout_height="30dp"
-        android:foreground="@drawable/gradient"
-        app:layout_constraintBottom_toTopOf="@+id/description" />
+        android:paddingEnd="16dp"
+        android:paddingBottom="3dp"
+        android:text="JUNE 3, 2018"
+        android:textSize="12sp"
+        app:layout_constraintRight_toRightOf="@+id/title"
+        app:layout_constraintTop_toBottomOf="@+id/title" />
 
     <TextView
         android:id="@+id/tap"
         android:layout_width="wrap_content"
         android:layout_height="wrap_content"
-        android:layout_marginBottom="8dp"
-        android:layout_marginEnd="8dp"
         android:layout_marginStart="8dp"
+        android:layout_marginEnd="8dp"
+        android:layout_marginBottom="8dp"
         android:text="Tap for info"
-        android:textSize="15sp"
         android:textColor="#ffffff"
+        android:textSize="15sp"
         app:layout_constraintBottom_toBottomOf="parent"
         app:layout_constraintEnd_toEndOf="parent"
         app:layout_constraintStart_toStartOf="parent" />
@@ -71,17 +66,24 @@
         android:id="@+id/description"
         android:layout_width="wrap_content"
         android:layout_height="wrap_content"
-        android:text="The Mugello is a historic region and valley in northern Tuscany, in Italy. It is located to the north of the city of Florence and consists of the northernmost portion of the Metropolitan City of Florence.  It is connected to the separate Santerno river valley by the Futa Pass."
-        android:textSize="22sp"
-        android:textColor="#FFFF"
-        android:gravity="center"
         android:background="#181818"
+        android:gravity="center"
         android:paddingStart="8dp"
         android:paddingEnd="8dp"
         android:paddingBottom="8dp"
+        android:text="The Mugello is a historic region and valley in northern Tuscany, in Italy. It is located to the north of the city of Florence and consists of the northernmost portion of the Metropolitan City of Florence.  It is connected to the separate Santerno river valley by the Futa Pass."
+        android:textColor="#FFFF"
+        android:textSize="22sp"
         app:layout_constraintBottom_toBottomOf="parent"
         app:layout_constraintLeft_toLeftOf="parent"
-        app:layout_constraintRight_toRightOf="parent"/>
+        app:layout_constraintRight_toRightOf="parent" />
+
+    <View
+        android:id="@+id/fadeBackgroudView"
+        android:layout_width="match_parent"
+        android:layout_height="30dp"
+        android:foreground="@drawable/gradient"
+        app:layout_constraintBottom_toTopOf="@+id/description" />
 
 
-</android.support.constraint.ConstraintLayout>
+</androidx.constraintlayout.widget.ConstraintLayout>

build.gradle

@@ -1,25 +1,8 @@
 // Top-level build file where you can add configuration options common to all sub-projects/modules.
-
-buildscript {
-    ext.kotlin_version = '1.2.21'
-    repositories {
-        google()
-        jcenter()
-    }
-    dependencies {
-        classpath 'com.android.tools.build:gradle:3.0.1'
-        classpath "org.jetbrains.kotlin:kotlin-gradle-plugin:$kotlin_version"
-
-        // NOTE: Do not place your application dependencies here; they belong
-        // in the individual module build.gradle files
-    }
-}
-
-allprojects {
-    repositories {
-        google()
-        jcenter()
-    }
+plugins {
+    id "com.android.application" version "7.2.1" apply false
+    id "com.android.library" version "7.2.1" apply false
+    id "org.jetbrains.kotlin.android" version "1.7.20" apply false
 }
 
 task clean(type: Delete) {

gradle.properties

@@ -15,3 +15,5 @@ org.gradle.jvmargs=-Xmx1536m
 # This option should only be used with decoupled projects. More details, visit
 # http://www.gradle.org/docs/current/userguide/multi_project_builds.html#sec:decoupled_projects
 # org.gradle.parallel=true
+
+android.useAndroidX=true

gradle/wrapper/gradle-wrapper.properties

@@ -1,6 +1,6 @@
-#Sun Feb 04 11:49:22 CET 2018
+#Sun Jun 13 10:34:00 CEST 2021
 distributionBase=GRADLE_USER_HOME
+distributionUrl=https\://services.gradle.org/distributions/gradle-7.3.3-bin.zip
 distributionPath=wrapper/dists
-zipStoreBase=GRADLE_USER_HOME
 zipStorePath=wrapper/dists
-distributionUrl=https\://services.gradle.org/distributions/gradle-4.1-all.zip
+zipStoreBase=GRADLE_USER_HOME