Life without Fragments

Google recommends that you use fragments to build a flexible UI. In cases when we need to optimize the UI for tablets or implement ViewPager this is indeed the easiest way.

Anyway, using fragments isn’t that easy. Anyone who’ve ever seen a diagram of their life cycle, understands the statement well :wink: Potential memory leaks, a complex API, and bugs (the number of questions on StackOverflow more than 100 000). And this doesn’t look as a brilliant idea anymore.

But what are the alternatives?

Video: https://www.youtube.com/watch?v=LidlAkrYKGg
Demo: https://github.com/johnkil/android-without-fragments

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Links:
https://github.com/weefbellington/screenplay
https://github.com/nhaarman/Triad
https://github.com/doridori/Pilot
https://github.com/mattlogan/Pancakes
https://github.com/lyft/scoop
https://github.com/bluelinelabs/Conductor
https://github.com/sockeqwe/mosby-conductor
https://www.reddit.com/r/androiddev/comments/2iodnx/advocating_against_android_fragments/
https://medium.com/square-corner-blog/advocating-against-android-fragments-81fd0b462c97
https://eng.lyft.com/building-single-activity-apps-using-scoop-763d4271b41
https://speakerdeck.com/rock3r/life-without-fragments-with-eugenio-marletti
https://softwaremill.com/finally-getting-rid-of-android-fragments/
https://www.polidea.com/blog/Introduction_To_Single_Activity_Applications/
https://github.com/xxv/android-lifecycle

Transcript

1. Life without Fragments Evgeny Shishkin @johnkil
2. Why Fragments?
3. Fragments
4. Single Activity
6. FragmentManager + IllegalStateException
7. public empty constructor
9. github.com/JetradarMobile/multibackstack
10. Alternative?
11. Advocating Against Android Fragments by Square
12. View-based App
13. Flow (square) Conductor (bluelinelabs) Scoop (lyft) Pancakes (mattlogan) Pilot (doridori) Triad (nhaarman) Screenplay (weefbellington)
14. Screenplay
15. Screenplay Stage Rigger Component #1 Component #2 Create setUp tearDown Destroy
16. Screenplay class LoginStage(val app: ScreenplayApp) : XmlStage() {
 val rigger by lazy { CrossFadeRigger(app) }
 
 init {
 addComponents(SignInComponent(app))
 }
 
 override fun getLayoutId(): Int {
 return R.layout.stage_login
 }
 
 override fun getRigger(): Stage.Rigger {
 return rigger
 }
 
 private class SignInComponent(val app: ScreenplayApp) : Component {
 override fun afterSetUp(stage: Stage, isInitializing: Boolean) {
 val signInButton = stage.view.findViewById(R.id.sign_in_button)
 signInButton.setOnClickListener { signIn() }
 }
 
 private fun signIn() {
 app.appFlow.set(WelcomeStage(app))
 }
 
 override fun beforeTearDown(stage: Stage, isFinishing: Boolean) {
 }
 }
 }
17. Triad
18. Triad Presenter Container Screen View Create onCreate onAttach Destroy onDetach onDestroy
19. Triad class LoginScreen : Screen<ApplicationComponent>() {
 
 override val layoutResId = R.layout.screen_login
 
 override fun createPresenter(viewId: Int) = LoginPresenter(applicationComponent.triad)
 }
 
 interface LoginContainer : Container {
 fun setUpEmail(email: String)
 fun setUpPassword(password: String)
 }
 
 class LoginPresenter(private val triad: Triad) : BasePresenter<LoginContainer, ActivityComponent>() {
 
 fun signInButtonClicked() {
 triad.goTo(WelcomeScreen())
 }
 }
 
 class LoginView @JvmOverloads constructor(context: Context, attrs: AttributeSet? = null, defStyle: Int = 0) :
 LinearLayoutContainer<LoginPresenter, ActivityComponent>(context, attrs,
 defStyle), LoginContainer {
 
 override fun onFinishInflate() {
 super.onFinishInflate()
 signInButton.setOnClickListener { presenter.signInButtonClicked() }
 }
 
 override fun setUpEmail(email: String) {
 emailEdit.setText(email)
 }
 
 override fun setUpPassword(password: String) {
 passwordEdit.setText(password)
 }
 }
20. Pilot
21. Pancakes
22. Pancakes ViewStack UIContainer Previous view Next view LayoutId
23. Pancakes class LoginView(context: Context, attrs: AttributeSet) : LinearLayout(context, attrs) {
 
 override fun onFinishInflate() {
 super.onFinishInflate()
 if (isInEditMode) return
 
 val signInButton = findViewById(R.id.sign_in_button)
 signInButton.setOnClickListener { signIn() }
 }
 
 private fun signIn() {
 val viewStack = (context as ViewStackActivity).viewStack()
 viewStack.pushWithAnimation(R.layout.view_welcome, CircularReveal())
 }
 }
24. Scoop
25. Scoop • Screen • Router • ViewController • Layout • Transitions
26. Scoop Router UIContainer Previous view Next view Screen Route change
27. Scoop @EnterTransition(FadeTransition::class)
 @ExitTransition(FadeTransition::class)
 @Controller(LoginController::class)
 class LoginScreen : Screen()
 
 class LoginController : ViewController() {
 override fun layoutId() = R.layout.screen_login
 
 override fun onAttach() {
 val signInButton = view.findViewById(R.id.sign_in_button)
 signInButton.setOnClickListener { signIn() }
 }
 
 private fun signIn() {
 router.goTo(WelcomeScreen())
 }
 }
28. Conductor
29. Conductor
30. Conductor • Controller • Router • RouterTransaction • ControllerChangeHandler
31. Conductor class LoginController : Controller() {
 
 override fun onCreateView(inflater: LayoutInflater, container: ViewGroup): View {
 val view = inflater.inflate(R.layout.controller_login, container, false)
 val signInButton = view.findViewById(R.id.sign_in_button)
 signInButton.setOnClickListener { signIn() }
 return view
 }
 
 private fun signIn() {
 router.pushController(RouterTransaction.with(WelcomeController())
 .pushChangeHandler(SimpleSwapChangeHandler())
 .popChangeHandler(SimpleSwapChangeHandler()))
 }
 }
32. Conductor + Mosby
33. Conductor + Mosby class LoginController : MvpController<LoginView, LoginPresenter>(), LoginView {
 
 override fun createPresenter() = LoginPresenter()
 
 override fun onCreateView(inflater: LayoutInflater, container: ViewGroup): View {
 val view = inflater.inflate(R.layout.controller_login, container, false)
 val signInButton = view.findViewById(R.id.sign_in_button)
 signInButton.setOnClickListener { presenter.signInButtonClicked() }
 return view
 }
 
 override fun showWelcomeScreen() {
 router.pushController(RouterTransaction.with(WelcomeController())
 .pushChangeHandler(SimpleSwapChangeHandler())
 .popChangeHandler(SimpleSwapChangeHandler()))
 }
 }
 
 interface LoginView : MvpView {
 fun showWelcomeScreen()
 }
 
 class LoginPresenter : MvpBasePresenter<LoginView>() {
 
 fun signInButtonClicked() {
 view?.showWelcomeScreen()
 }
 }
34. github.com/johnkil/android-without-fragments
35. Thank You
37. Links