In the created main_activity layout, we'll show a list of the user details where we show the name, email ID, and contact number of a user—we'll use ListView.

Here's the code of the mainActivity layout of the MainActivity class:

<?xml version="1.0" encoding="utf-8"?>
<android.support.constraint.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">

    <TextView
        android:id="@+id/textView"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:text="@string/user_title"
        app:layout_constraintEnd_toEndOf="parent"
        android:textStyle="bold"
        android:padding="5dp"
        android:gravity="center_horizontal"
        android:textAppearance="?android:textAppearanceLarge"
        app:layout_constraintStart_toStartOf="parent"
        app:layout_constraintTop_toTopOf="parent" />

    <ListView
        android:id="@+id/displayList"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:layout_marginStart="8dp"
        android:layout_marginLeft="8dp"
        android:layout_marginTop="8dp"
        android:layout_marginEnd="8dp"
        android:layout_marginRight="8dp"
        app:layout_constraintEnd_toEndOf="parent"
        app:layout_constraintStart_toStartOf="parent"
        app:layout_constraintTop_toBottomOf="@+id/textView" />

</android.support.constraint.ConstraintLayout>

In this layout, we have one TextView and one ListView.

We'll use this ListView in the onResponse() function of MainActivity. 

We'll get the list and create a custom adapter to show the user list, as follows:

val adapter = UserListAdapter(this@MainActivity, 
response.body()//this is a arraylist 
)

Here, we have a custom adapter where we'll send the context and the Array list of the users.