A default AppCompatActivity that hosts a Fragment.

activity_single_fragment.xml

<?xml version="1.0" encoding="utf-8"?>
<androidx.fragment.app.FragmentContainerView xmlns:android="http://schemas.android.com/apk/res/android"
    android:id="@+id/fragmentContainerView"
    android:layout_width="match_parent"
    android:layout_height="match_parent" />

SingleFragmentActivity.kt

import android.content.Intent
import android.os.Bundle
import androidx.annotation.CallSuper
import androidx.appcompat.app.AppCompatActivity
import androidx.fragment.app.Fragment
import androidx.fragment.app.FragmentContainerView
import androidx.fragment.app.commitNow
import com.deliveryhero.commons.mvvm.R
import kotlin.reflect.KClass

/**
 * A default [AppCompatActivity] that hosts a [Fragment].
 *
 * [SingleFragmentActivity] has a default layout [R.layout.activity_single_fragment]
 * that consists of a single, full-screen [FragmentContainerView] in the center of the
 * screen.
 *
 * Any extra set in the activity [Intent] will be automatically redirect to the
 * displayed [Fragment].
 *
 * [SingleFragmentActivity] was designed to be used when migrating to a "Single
 * Activity Architecture" in small steps: first converting multiple activities to
 * fragments hosted by multiple [SingleFragmentActivity] without breaking changes
 * and finally, using a NavGraph - if you are planning to use JetPack Navigation -
 * to do the wiring of all these fragments inside a host [AppCompatActivity].
 *
 * Note this class has been designed to support child fragments, but you should
 * NOT change the single fragment or this would result in unexpected behaviour.
 *
 * Usage example:
 * ```
 * class MyActivity : SingleFragmentActivity(MyFragment::class)
 * ```
 */
abstract class SingleFragmentActivity(
    private val fragmentClass: KClass<out Fragment>
) : AppCompatActivity() {

    @CallSuper
    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)

        setContentView(R.layout.activity_single_fragment)

        supportFragmentManager.findFragmentById(R.id.fragmentContainerView) ?: return

        val fragment = supportFragmentManager.fragmentFactory
            .instantiate(classLoader, fragmentClass.java.name)
            .apply { arguments = intent?.extras }

        supportFragmentManager.commitNow {
            setReorderingAllowed(true)
            add(R.id.fragmentContainerView, fragment)
            setPrimaryNavigationFragment(fragment)
        }
    }
}