adicionei o comentario

app/src/main/java/com/example/teste/MainActivity.java

@@ -20,5 +20,6 @@ public class MainActivity extends AppCompatActivity {
             v.setPadding(systemBars.left, systemBars.top, systemBars.right, systemBars.bottom);
             return insets;
         });
+        // adicionei codigo aqui
     }
 }

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

@@ -16,4 +16,12 @@
         app:layout_constraintStart_toStartOf="parent"
         app:layout_constraintTop_toTopOf="parent" />
 
+    <Button
+        android:id="@+id/button"
+        android:layout_width="wrap_content"
+        android:layout_height="wrap_content"
+        android:text="Button"
+        tools:layout_editor_absoluteX="168dp"
+        tools:layout_editor_absoluteY="341dp" />
+
 </androidx.constraintlayout.widget.ConstraintLayout>