Building the interface

To be able to place and manage the call, you need to add few elements to the screen:

• Button to login Alice user
• Button to login Bob user
• A TextView to show the connection status
• A Button to start the call
• A Button to end the call
• A Button to answer the call
• A Button to reject the call

Open the app/res/layout/activity_main.xml file. Click the Code button in the top right corner:

Replace the file contents with the following:

You will control the view using code, so you have to store references to the views. Add these properties at the top of the ManActivity class:

Now you need to assign views to previously added properties and add callbacks to the buttons. Add below code to the onCreate method inside MainActivity class (below request permissions code):

To make code compile add these two empty methods in the MainActivity class:

private fun loginAsAlice() {
    // TODO: update body
}

private fun loginAsBob() {
    // TODO: update body
}

You will fill the body of these methods in the following steps of this tutorial.

Build and Run

Run the project again (Ctrl + R).

Notice that some views are hidden by default. After launching the app you will see login alice and login bob buttons: