fixed errors

app/build.gradle

@@ -35,11 +35,11 @@ android {
 dependencies {
 
     implementation "org.jetbrains.kotlin:kotlin-stdlib:$kotlin_version"
-    implementation 'com.android.support:appcompat-v7:28.0.0'
+    //implementation 'com.android.support:appcompat-v7:28.0.0'
     implementation 'com.android.support.constraint:constraint-layout:2.0.4'
     implementation "androidx.recyclerview:recyclerview:1.1.0"
     implementation 'androidx.constraintlayout:constraintlayout:1.1.3'
     testImplementation 'junit:junit:4.+'
-    androidTestImplementation 'com.android.support.test:runner:1.0.2'
+    //androidTestImplementation 'com.android.support.test:runner:1.0.2'
     androidTestImplementation 'com.android.support.test.espresso:espresso-core:3.0.2'
 }
\ No newline at end of file

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

@@ -15,4 +15,14 @@
         app:layout_constraintStart_toStartOf="parent"
         app:layout_constraintTop_toTopOf="parent" />
 
+    <Button
+        android:id="@+id/button3"
+        android:layout_width="wrap_content"
+        android:layout_height="wrap_content"
+        android:layout_marginEnd="30dp"
+        android:layout_marginBottom="30dp"
+        android:text="Button"
+        app:layout_constraintBottom_toBottomOf="parent"
+        app:layout_constraintEnd_toEndOf="parent" />
+
 </androidx.constraintlayout.widget.ConstraintLayout>
\ No newline at end of file

gradle.properties

@@ -12,4 +12,5 @@ org.gradle.jvmargs=-Xmx2048m -Dfile.encoding=UTF-8
 # http://www.gradle.org/docs/current/userguide/multi_project_builds.html#sec:decoupled_projects
 # org.gradle.parallel=true
 # Kotlin code style for this project: "official" or "obsolete":
-kotlin.code.style=official
+kotlin.code.style=official
\ No newline at end of file
+android.useAndroidX=true
\ No newline at end of file