For Full video click on below link :- https://youtu.be/RdKznpj3p30?si=41W4Dj0focRWbFln Working with the activity_main.xml file. Navigate to the app > res > layout > activity_main.xml and add the below code to that file. Below is the code for the activity_main.xml file. <?xml version="1.0" encoding="utf-8"?> <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:layout_width="match_parent" android:layout_height="match_parent" tools:context=".MainActivity" android:background="@color/white"> <Button android:id="@+id/openbtn" android:layout_width="150dp" android:layout_height="50dp" ...