MainActivity_InAppUpdates_Listener.kt

class MainActivity : AppCompatActivity(), InstallStateUpdatedListener {
    override fun onStateUpdate(installState: InstallState) {
        if (installState.installStatus() == InstallStatus.DOWNLOADED) {
            notifyUser()
        }
    }
    
    super.onCreate(savedInstanceState)
        setContentView(R.layout.activity_main)

        appUpdateManager = AppUpdateManagerFactory.create(this)
        appUpdateManager.registerListener(this)
        
        appUpdateManager.appUpdateInfo.addOnSuccessListener {
        if (it.updateAvailability() == UpdateAvailability.UPDATE_AVAILABLE &&
            it.isUpdateTypeAllowed(AppUpdateType.FLEXIBLE)) {   //  check for the type of update flow you want
            requestUpdate()
        }
    }
    
    override fun onDestroy() {
        super.onDestroy()
        appUpdateManager.unregisterListener(this)
    }
    
    private fun notifyUser() {
        Snackbar
            .make(appVersionTextView, R.string.restart_to_update, Snackbar.LENGTH_INDEFINITE)
            .setAction(R.string.action_restart) {
                appUpdateManager.completeUpdate()
                appUpdateManager.unregisterListener(this)
            }
            .show()
    }
}