I'm having a problem where when executing
findNavController(R.id.main_nav_host).navigateUp()
or
findNavController(R.id.main_nav_host).popBackStack()
Instead of going back to the last fragment in the backstack, it reopens/navigates to the same/current fragment.
Can somebody point me in the right direction why this is happening?
Navigation graph:
<navigation 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:id="#+id/main_navigation_root"
app:startDestination="#+id/dest_main">
<fragment
android:id="#+id/dest_main"
android:name="com.example.popularmovies.ui.main.views.MainMoviesFragment"
android:label="#string/home"
tools:layout="#layout/fragment_main_movies">
<action
android:id="#+id/action_dest_main_to_dest_movie_details"
app:destination="#+id/dest_movie_details"
app:enterAnim="#anim/slide_in_right"
app:exitAnim="#anim/slide_out_left"
app:popEnterAnim="#anim/slide_in_left"
app:popExitAnim="#anim/slide_out_right" />
</fragment>
<fragment
android:id="#+id/dest_movie_details"
android:name="com.example.popularmovies.ui.details.movie.view.MovieDetailsFragment"
android:label="#string/movie_details"
tools:layout="#layout/fragment_movie_details"/>
</navigation>
MainActivity layout:
<FrameLayout
xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:app="http://schemas.android.com/apk/res-auto"
android:layout_width="match_parent"
android:layout_height="match_parent"
app:layout_behavior="#string/appbar_scrolling_view_behavior">
<fragment
android:id="#+id/main_nav_host"
android:name="androidx.navigation.fragment.NavHostFragment"
android:layout_width="match_parent"
android:layout_height="match_parent"
app:defaultNavHost="true"
app:navGraph="#navigation/main_navigation"/>
</FrameLayout>
MainActivity:
class MainActivity : AppCompatActivity(), HasSupportFragmentInjector {
#Inject
lateinit var dispatchingAndroidInjector: DispatchingAndroidInjector<Fragment>
private lateinit var appBarConfiguration: AppBarConfiguration
override fun onCreate(savedInstanceState: Bundle?) {
super.onCreate(savedInstanceState)
setContentView(R.layout.activity_main)
setSupportActionBar(toolbar)
initNavUi()
}
override fun onBackPressed() {
findNavController(R.id.main_nav_host).popBackStack()
}
override fun onCreateOptionsMenu(menu: Menu): Boolean {
// Inflate the menu; this adds items to the action bar if it is present.
menuInflater.inflate(R.menu.menu_main, menu)
return true
}
override fun onOptionsItemSelected(item: MenuItem): Boolean {
// Handle action bar item clicks here. The action bar will
// automatically handle clicks on the Home/Up button, so long
// as you specify a parent activity in AndroidManifest.xml.
return when (item.itemId) {
R.id.action_settings -> true
else -> super.onOptionsItemSelected(item)
}
}
override fun onSupportNavigateUp(): Boolean {
return findNavController(R.id.main_nav_host).navigateUp()
}
override fun supportFragmentInjector(): AndroidInjector<Fragment> {
return dispatchingAndroidInjector
}
private fun initNavUi() {
val navController = Navigation.findNavController(this, R.id.main_nav_host)
appBarConfiguration = AppBarConfiguration(
setOf(R.id.dest_main)
)
NavigationUI.setupActionBarWithNavController(this, navController, appBarConfiguration)
}
}
Destination home fragment:
class MainMoviesFragment : Fragment(), Injectable, MovieViewHolder.MovieClickListener {
#Inject
lateinit var viewModelFactory: ViewModelProvider.Factory
private lateinit var fragmentViewModel: MainMoviesFragmentViewModel
private lateinit var moviesRv: RecyclerView
private lateinit var moviesAdapter: MainMoviesAdapter
override fun onCreateView(inflater: LayoutInflater, container: ViewGroup?, savedInstanceState: Bundle?): View? {
return inflater.inflate(R.layout.fragment_main_movies, container, false)
}
override fun onViewCreated(view: View, savedInstanceState: Bundle?) {
super.onViewCreated(view, savedInstanceState)
initViews(view)
}
override fun onActivityCreated(savedInstanceState: Bundle?) {
super.onActivityCreated(savedInstanceState)
fragmentViewModel = ViewModelProviders.of(this,viewModelFactory).get(MainMoviesFragmentViewModel::class.java)
fragmentViewModel.start()
observe()
}
override fun onMovieClicked(position: Int) {
fragmentViewModel.onMovieClicked(position)
}
private fun initViews(view: View) {
moviesRv = view.findViewById<RecyclerView>(R.id.fragment_main_movies_rv).apply{
layoutManager = LinearLayoutManager(context)
setHasFixedSize(true)
moviesAdapter = MainMoviesAdapter(this#MainMoviesFragment)
adapter = moviesAdapter
}
}
private fun observe() {
fragmentViewModel.moviesLiveData.observe(this, Observer { moviesAdapter.submitList(it) })
fragmentViewModel.onMovieClickedLiveEvent.observe(this, Observer { handleMovieClickedEvent(it) })
}
private fun handleMovieClickedEvent(movieModel: MovieModel?){
val action = MainMoviesFragmentDirections.actionDestMainToDestMovieDetails()
findNavController().navigate(action)
}
}
Destination target fragment:
class MovieDetailsFragment : Fragment() {
private lateinit var viewModel: MovieDetailsFragmentViewModel
override fun onCreateView(inflater: LayoutInflater, container: ViewGroup?, savedInstanceState: Bundle?): View? {
return inflater.inflate(R.layout.fragment_movie_details, container, false)
}
override fun onActivityCreated(savedInstanceState: Bundle?) {
super.onActivityCreated(savedInstanceState)
viewModel = ViewModelProviders.of(this).get(MovieDetailsFragmentViewModel::class.java)
}
}
The project code on GitHub can be found here
Your onMovieClickedLiveEvent, used in your MainMoviesFragmentViewModel, is firing every time you go back to your MainMoviesFragment since MutableLiveData saves the current value. This means that popBackStack() works just fine, but then you instantly get navigated back to the detail page (note: you'll still want to remove your code in onBackPressed() since right now you can't exit the app by hitting the back button).
It seems like, particularly with the name of the variable, that you should be using the SingleLiveEvent class, instead of MutableLiveData directly, as per this blog post.
Of course, there's no particular reason to use a LiveData or go through the ViewModel at all in this case. Your MovieViewHolder could pass the MovieModel directly to onMovieClicked, which could call handleMovieClickedEvent directly. That would avoid the use of LiveData (which is designed to store state, not events) and better model what you actually want to achieve: an event listener.
Related
In my project that makes open new fragment with NavigationComponenet when click button. I want to test if fragment open when click button, But it don't work properly. Only it click button and does not open another fragment. So, I can't test if it works. Why it does not navigate?
#RunWith(AndroidJUnit4::class)
class WelcomeFragmentTestDoctor {
val phoneHelper = PhoneHelper
private lateinit var scenario: FragmentScenario<WelcomeFragment>
#Before
fun setup() {
scenario = launchFragmentInContainer(themeResId = R.style.AppTheme)
scenario.moveToState(Lifecycle.State.STARTED)
Intents.init()
}
#After
fun tearDown(){
Intents.release()
}
#Test
fun clickApplyAsADoctor(){
val navController = TestNavHostController(
ApplicationProvider.getApplicationContext())
scenario.onFragment { fragment ->
navController.setGraph(R.navigation.auth_navigation)
Navigation.setViewNavController(fragment.requireView(), navController)
}
onView(withId(R.id.buttonDoctor)).perform(click())
Assert.assertEquals(navController.currentDestination?.id, R.id.action_welcomeFragment_to_doctorRegistrationFragment)
}
}
fragment_doctor_registration.xml
<?xml version="1.0" encoding="utf-8"?>
<layout 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">
<androidx.constraintlayout.widget.ConstraintLayout
android:layout_width="match_parent"
android:layout_height="match_parent">
<androidx.constraintlayout.widget.ConstraintLayout
android:id="#+id/toolbar"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:paddingTop="#dimen/_14sdp"
android:paddingBottom="#dimen/_14sdp"
app:layout_constraintTop_toTopOf="parent">
</androidx.constraintlayout.widget.ConstraintLayout>
</androidx.core.widget.NestedScrollView>
</androidx.constraintlayout.widget.ConstraintLayout>
</layout>
DoctorRegistrationFragment.kt
class DoctorRegistrationFragment : Fragment() {
private lateinit var mBinding: FragmentDoctorRegistrationBinding
private val mViewModel: DoctorRegistrationViewModel by inject()
override fun onCreate(savedInstanceState: Bundle?) {
super.onCreate(savedInstanceState)
}
override fun onCreateView(inflater: LayoutInflater, container: ViewGroup?, savedInstanceState: Bundle?): View? {
mBinding = FragmentDoctorRegistrationBinding.inflate(inflater, container, false)
return mBinding.root
}
override fun onViewCreated(view: View, savedInstanceState: Bundle?) {
super.onViewCreated(view, savedInstanceState)
DoctorRegistrationComponent.inject()
with(mBinding) {
backButton.setOnCrashOnClickListener {
findNavController().popBackStack()
}
btnSend.setOnCrashOnClickListener {
mViewModel.onEvent(
DoctorRegistrationInteractions.RegisterStart(fdr_name.text, fdr_surname.text,
fdr_title.text, fdr_diploma.text, fdr_branch.text,
inputLogin.lifEdittext.text.toString(), fdr_email.text, fdr_address.text,
fdr_company.text, fdr_tax.text
))
}
}
with(mViewModel) {
actions.map { it.getContentIfNotHandled() }.onEach(::handleActions).launchIn(viewLifecycleOwner.lifecycleScope)
}
}
private fun handleActions(action: DoctorRegistrationActions) {
when (action) {
is DoctorRegistrationActions.ErrorMessage -> PopupMessage.error(requireActivity(),message = action.message)
DoctorRegistrationActions.Init -> { }
is DoctorRegistrationActions.SuccessMessage -> {
PopupMessage.success(requireActivity(), message = action.message)
findNavController().popBackStack()
}
}
}
}
You need to check the fragment id not the Action id
Assert.assertEquals(navController.currentDestination?.id, R.id.doctorRegistrationFragment)
Assuming that doctorRegistrationFragment is the id of your fragment tag in your nav graph
<fragment
android:id="#+id/doctorRegistrationFragment"
/* rest of attrs */ >
The title itself is my problem, whenever I open MainActivity then navigate to another fragment available in the hamburger/drawer menu then press/swipe back to return in main screen (first fragment) it recreates. Is there away for Nav Component to make it not recreate the first fragment? I am using the Jetpack Navigation template generated by Android Studio and it seems that is the default behavior.
This is the MainActivity
class MainActivity : AppCompatActivity() {
private lateinit var appBarConfiguration: AppBarConfiguration
private var _binding: ActivityMainBinding? = null
// This property is only valid between onCreate and
// onDestroyView.
private val binding get() = _binding!!
private lateinit var drawerLayout: DrawerLayout
override fun onCreate(savedInstanceState: Bundle?) {
super.onCreate(savedInstanceState)
_binding = ActivityMainBinding.inflate(layoutInflater)
setContentView(binding.root)
setSupportActionBar(binding.appBarMain.toolbar)
drawerLayout = binding.drawerLayout
val navView: NavigationView = binding.navView
val navController = findNavController(R.id.nav_host_fragment_content_main)
// Passing each menu ID as a set of Ids because each
// menu should be considered as top level destinations.
appBarConfiguration = AppBarConfiguration(setOf(
R.id.nav_home, R.id.nav_marketcap, R.id.nav_about), drawerLayout)
setupActionBarWithNavController(navController, appBarConfiguration)
navView.setupWithNavController(navController)
}
override fun onCreateOptionsMenu(menu: Menu): Boolean {
// Inflate the menu; this adds items to the action bar if it is present.
menuInflater.inflate(R.menu.main, menu)
menu.findItem(R.id.action_settings).isChecked = AppCompatDelegate.getDefaultNightMode() == AppCompatDelegate.MODE_NIGHT_YES
return true
}
override fun onSupportNavigateUp(): Boolean {
val navController = findNavController(R.id.nav_host_fragment_content_main)
return navController.navigateUp(appBarConfiguration) || super.onSupportNavigateUp()
}
override fun onDestroy() {
super.onDestroy()
_binding = null
}
override fun onBackPressed() {
if (drawerLayout.isDrawerOpen(GravityCompat.START))
drawerLayout.closeDrawer(GravityCompat.START)
else
super.onBackPressed()
}
}
This is the Home Fragment (The first fragment in MainActivity) that holds child fragment AssetFragment
class HomeFragment : Fragment() {
private val homeViewModel: HomeViewModel by activityViewModels()
private var _binding: FragmentHomeBinding? = null
// This property is only valid between onCreateView and
// onDestroyView.
private val binding get() = _binding!!
private lateinit var viewPager : ViewPager2
override fun onCreateView(
inflater: LayoutInflater,
container: ViewGroup?,
savedInstanceState: Bundle?
): View {
_binding = FragmentHomeBinding.inflate(inflater, container, false)
val root: View = binding.root
viewPager = binding.viewPagerContainer
val bottomNav = binding.bottomNav
// val tabLayout = binding.tabLayout
val fragmentList : MutableList<Pair<String, Fragment>> = mutableListOf()
fragmentList.add(Pair(getString(R.string.assets), AssetFragment.newInstance()))
fragmentList.add(Pair(getString(R.string.news), NewsFragment.newInstance()))
fragmentList.add(Pair(getString(R.string.videos), VideosFragment.newInstance()))
val adapter = AppFragmentAdapter(fragmentList, this)
viewPager.adapter = adapter
viewPager.offscreenPageLimit = 2
viewPager.registerOnPageChangeCallback(object : ViewPager2.OnPageChangeCallback() {
override fun onPageSelected(position: Int) {
super.onPageSelected(position)
bottomNav.menu.getItem(position).isChecked = true
homeViewModel.setTitle(adapter.getFragmentTabName(position))
}
})
val bottomNavListener = BottomNavigationView.OnNavigationItemSelectedListener { item ->
when(item.itemId) {
R.id.page_1 -> {
// Respond to navigation item 1 click
viewPager.setCurrentItem(0, true)
true
}
R.id.page_2 -> {
// Respond to navigation item 2 click
viewPager.setCurrentItem(1, true)
true
}
R.id.page_3 -> {
// Respond to navigation item 3 click
viewPager.setCurrentItem(2, true)
true
}
else -> false
}
}
bottomNav.setOnNavigationItemSelectedListener(bottomNavListener)
// val layoutInflater : LayoutInflater = LayoutInflater.from(context)
//Connect TabLayout with ViewPager2
// TabLayoutMediator(tabLayout, viewPager){ tab, position ->
// tab.customView = prepareTabView(layoutInflater, tabLayout, adapter.getFragmentTabName(position), tabIcons[position])
// }.attach()
return root
}
// private fun prepareTabView(
// layoutInflater: LayoutInflater,
// tabLayout: TabLayout,
// fragmentName: String,
// drawableId: Int
// ): View {
//
// val rootView : View = layoutInflater.inflate(R.layout.main_custom_tab_text, tabLayout, false)
//
// val tabName : AppCompatTextView = rootView.findViewById(R.id.tabName)
//
// tabName.text = fragmentName
// tabName.setCompoundDrawablesWithIntrinsicBounds(null, AppCompatResources.getDrawable(requireContext(), drawableId), null, null)
//
// return tabName
//
// }
override fun onDestroyView() {
super.onDestroyView()
_binding = null
}
override fun onResume() {
super.onResume()
requireView().isFocusableInTouchMode = true
requireView().requestFocus()
requireView().setOnKeyListener(object : View.OnKeyListener {
override fun onKey(v: View?, keyCode: Int, event: KeyEvent?): Boolean {
if (event!!.action == KeyEvent.ACTION_UP && keyCode == KeyEvent.KEYCODE_BACK) {
onBackPress()
return true
}
return false
}
})
}
fun onBackPress() {
if (viewPager.currentItem != 0)
viewPager.setCurrentItem(0, true)
else
requireActivity().onBackPressed()
}
}
This is one of the child fragment displayed in ViewPager hosted by parent fragment HomeFragment
class AssetFragment : Fragment() {
companion object {
fun newInstance() = AssetFragment()
}
private lateinit var viewModel: AssetViewModel
private var _binding: FragmentAssetsBinding? = null
// This property is only valid between onCreateView and
// onDestroyView.
private val binding get() = _binding!!
private lateinit var logTxt: AppCompatTextView
private lateinit var recyclerView: RecyclerView
private lateinit var swipeRefreshLayout: SwipeRefreshLayout
override fun onCreateView(
inflater: LayoutInflater, container: ViewGroup?,
savedInstanceState: Bundle?,
): View {
_binding = FragmentAssetsBinding.inflate(inflater, container, false)
val root: View = binding.root
recyclerView = binding.recyclerView
swipeRefreshLayout = binding.refreshLayout
logTxt = binding.errorLog
recyclerView.layoutManager = LinearLayoutManager(context)
adapter = AssetAdapter(requireContext(), this)
recyclerView.adapter = adapter
swipeRefreshLayout.isRefreshing = true
fetchAssets("30")
swipeRefreshLayout.setOnRefreshListener {
swipeRefreshLayout.isRefreshing = true
fetchAssets("30")
}
return root
}
private fun fetchAssets(limit: String) {
//Network stuff
}
override fun onActivityCreated(savedInstanceState: Bundle?) {
super.onActivityCreated(savedInstanceState)
viewModel = ViewModelProvider(this).get(AssetViewModel::class.java)
// TODO: Use the ViewModel
}
override fun onDestroyView() {
super.onDestroyView()
_binding = null
}
}
Navigation xml
This are the fragments that will be shown in the drawer menu
<?xml version="1.0" encoding="utf-8"?>
<navigation 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:id="#+id/mobile_navigation"
app:startDestination="#+id/nav_home">
<fragment
android:id="#+id/nav_home"
android:name="com.myapp.ui.home.HomeFragment"
android:label="#string/home"
tools:layout="#layout/fragment_home" />
<fragment
android:id="#+id/nav_marketcap"
android:name="com.myapp.ui.marketcap.MarketCapFragment"
android:label="#string/marketCap"
tools:layout="#layout/fragment_marketcap" />
<fragment
android:id="#+id/nav_about"
android:name="com.myapp.ui.about.AboutFragment"
android:label="#string/about"
tools:layout="#layout/fragment_about" />
</navigation>
The menu.xml
<?xml version="1.0" encoding="utf-8"?>
<menu xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools"
tools:showIn="navigation_view">
<group android:checkableBehavior="single">
<item android:title="#string/menu">
<menu>
<item
android:id="#+id/nav_home"
android:icon="#drawable/ic_assets"
android:title="#string/home" />
<item
android:id="#+id/nav_marketcap"
android:icon="#drawable/ic_marketcap"
android:title="#string/marketCap" />
<item
android:id="#+id/nav_about"
android:icon="#drawable/ic_about"
android:title="#string/about" />
</menu>
</item>
</group>
<item android:title="#string/connect">
<menu>
<item
android:id="#+id/email_connect"
android:icon="#drawable/ic_email"
android:title="#string/fui_email_hint" />
</menu>
</item>
</menu>
Flow:
Open the app
Launching the MainActivity
Show HomeFragment (AssetFragment)
Open drawer menu
Select item e.g. About (AboutFragment)
Press/Swipe back
Problem here The HomeFragment onCreateView is being triggered once again
Expected behavior HomeFragment will no longer need to inflate view since we just literally make the user back to the very first destination. Unless a user itself press Home item in our drawer menu, that is the time HomeFragment will be recreated.
As per the Saving state with fragments guide, it is expected that your Fragment's view (but not the fragment itself) is destroyed and recreated when it is on the back stack.
As per that guide, one of the types of state is non config state:
NonConfig: data pulled from an external source, such as a server or local repository, or user-created data that is sent to a server once committed.
NonConfig data should be placed outside of your fragment, such as in a ViewModel. The ViewModel class inherently allows data to survive configuration changes, such as screen rotations, and remains in memory when the fragment is placed on the back stack.
So your fragment should never be calling fetchAssets("30") in onCreateView(). Instead, this logic should happen inside a ViewModel such that it is instantly available when the fragment returns from the back stack. As per the ViewModel guide, your fetchAssets should be done inside the ViewModel and your Fragment would observe that data.
I have an app with 3 main destinations which can be accessed by a bottom nav view. Each destination has its own navigation graph.
The problem is that when I minimize and reopen my app, the navigation components reset to the default destination. Why does this happen?
My main activity: (Irrelevant code omitted)
class MainActivity : AppCompatActivity() {
// List of base host containers
val fragments = listOf(
HomeHostFragment(),
CoursesHostFragment(),
SearchHostFragment()
)
override fun onCreate(savedInstanceState: Bundle?) {
super.onCreate(savedInstanceState)
setContentView(R.layout.activity_main)
val viewPager: ViewPager = findViewById(R.id.main_activity_pager)
viewPager.adapter = ViewPagerAdapter()
}
inner class ViewPagerAdapter : FragmentPagerAdapter(supportFragmentManager) {
override fun getItem(position: Int): Fragment =
fragments[position]
override fun getCount(): Int =
fragments.size
}
}
HomeHostFragment.kt:
class HomeHostFragment : Fragment() {
private lateinit var navController: NavController
override fun onCreateView(inflater: LayoutInflater, container: ViewGroup?, savedInstanceState: Bundle?): View? =
inflater.inflate(R.layout.fragment_home_host, container, false)
override fun onStart() {
super.onStart()
navController = requireActivity().findNavController(R.id.nav_host_home)
navController.setGraph(R.navigation.nav_graph_home)
NavigationUI.setupWithNavController(toolbar_home, navController)
}
fun onBackPressed(): Boolean {
return navController.navigateUp()
}
}
Whenever onStart() is called, NavigationUI.setupWithNavController() is called again which resets the navigation. Move this call to onViewCreated() so that the navigation setup is not done every time the fragment pauses and restarts.
I'm trying to implement the android jetpack navigation component.
The case is almost the same as in the official doc: https://developer.android.com/guide/navigation/navigation-conditional
But my case is, if the user hasn't logged in yet where the login access will be recorded in the database (Room),
then the system will force the user to login.
I use https://developer.android.com/guide/navigation/navigation-global-action to declare
destination to the login fragment
Then in order, the definition is as follows
Home Fragment is startDestination,
If no user data has been found in the database, display the login page
If the login is successful, bring the user back to home and save data login to database.
I use MVVM Architecture and Coroutine which runs requests to REST
using Retrofit.
Here are some code that I used:
Navigation (xml)
<navigation 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:id="#+id/nav"
app:startDestination="#id/homeFragment">
<fragment
android:id="#+id/homeFragment"
android:name="com.depo.trask.ui.home.HomeFragment"
android:label="#string/app_name"
tools:layout="#layout/fragment_home">
<argument android:name="authentication"
android:defaultValue="none" />
<action
android:id="#+id/action_homeFragment_to_settingsFragment"
app:destination="#id/settingsFragment" />
</fragment>
<fragment
android:id="#+id/settingsFragment"
android:name="com.depo.trask.ui.settings.SettingsFragment"
android:label="#string/settings" />
<fragment
android:id="#+id/loginFragment"
android:name="com.depo.trask.ui.login.LoginFragment"
android:label="fragment_login"
tools:layout="#layout/fragment_login" />
<action
android:id="#+id/action_global_loginFragment"
app:destination="#id/loginFragment"
app:launchSingleTop="false"
app:popUpTo="#+id/nav_host_fragment"
app:popUpToInclusive="true" />
</navigation>
MainActivity
class MainActivity : AppCompatActivity() {
private lateinit var navController: NavController
private lateinit var bottomNavigationView: BottomNavigationView
private lateinit var toolbar: Toolbar
private val navigationInMainScreen = setOf(
R.id.loginFragment,
R.id.homeFragment,
R.id.containerShippingFragment,
R.id.locationFragment,
R.id.historyFragment,
R.id.aboutFragment
)
override fun onCreate(savedInstanceState: Bundle?) {
setTheme(R.style.Theme_MyTheme)
super.onCreate(savedInstanceState)
setContentView(R.layout.activity_main)
setupNavController()
}
override fun onSupportNavigateUp(): Boolean {
navController.navigateUp()
return super.onSupportNavigateUp()
}
// Nav Controller
private fun setupNavController() {
navController = findNavController(R.id.nav_host_fragment)
setupActionBar()
setupBottomNavigationBar()
navController.addOnDestinationChangedListener { _, destination, _ ->
// Listening toolbar
when(destination.id){
R.id.loginFragment, R.id.aboutFragment -> toolbar.visibility = View.GONE
else -> toolbar.visibility = View.VISIBLE
}
// Listening bottom navigation bar
when (destination.id) {
R.id.loginFragment, R.id.settingsFragment -> bottomNavigationView.visibility = View.GONE
else -> bottomNavigationView.visibility = View.VISIBLE
}
}
}
// Top Bar OR App Bar
private fun setupActionBar() {
toolbar = findViewById(R.id.toolbar)
setSupportActionBar(toolbar)
val appBarConfiguration = AppBarConfiguration(
navigationInMainScreen
)
setupActionBarWithNavController(navController, appBarConfiguration)
}
// Bottom Navigation Bar
private fun setupBottomNavigationBar() {
bottomNavigationView = findViewById(R.id.bottom_navigation_view)
bottomNavigationView.setupWithNavController(navController)
}
}
Home Fragment
class HomeFragment : Fragment() {
?? Should I usede LoginViewModel ?
override fun onCreateView(
inflater: LayoutInflater,
container: ViewGroup?,
savedInstanceState: Bundle?
): View? {
return inflater.inflate(R.layout.fragment_home, container, false)
}
override fun onViewCreated(view: View, savedInstanceState: Bundle?) {
super.onViewCreated(view, savedInstanceState)
observeAuthenticationState()
}
private fun observeAuthenticationState() {
val navController = findNavController()
// REDIRECT USER TO LOGIN PAGE ?
// How To check it
navController.navigate(R.id.action_global_loginFragment)
}
}
Login Fragment
class LoginFragment : Fragment() {
private lateinit var viewModel: LoginViewModel // How can I shared this to home fragment
private lateinit var binding: FragmentLoginBinding
override fun onCreateView(
inflater: LayoutInflater,
container: ViewGroup?,
savedInstanceState: Bundle?
): View? {
// For Retrofit
val networkConnectionInterceptor = NetworkConnectionInterceptor(requireContext())
val api = MyApi(networkConnectionInterceptor)
// For Room
val db = AppDatabase(context = requireActivity().applicationContext)
// For ViewModel
val repository = UserRepository(api, db)
val factory = LoginViewModelFactory(repository)
binding = DataBindingUtil.inflate(
inflater,
R.layout.fragment_login,
container,
false
)
viewModel = ViewModelProvider(this, factory).get(LoginViewModel::class.java)
binding.buttonLogin.setOnClickListener { loginUser() }
return binding.root
}
private fun loginUser() {
val username = binding.editTextUsername.text.toString().trim()
val password = binding.editTextPassword.text.toString().trim()
binding.progressBar.show()
lifecycleScope.launch {
try {
val loginResponse = viewModel.userLogin(username!!, password!!)
if(loginResponse.user != null){
viewModel.saveLoggedInUser(loginResponse.user)
}
binding.progressBar.hide()
binding.root.context.toast(loginResponse.message!!)
} catch (e: ApiException) {
binding.progressBar.hide()
binding.root.context.toast( e.toString())
} catch (e: NoInternetException) {
binding.progressBar.hide()
binding.root.context.toast( e.toString())
}
}
}
}
My question ?
How to force users to log in fragments correctly on home fragments?
How to use LoginViewModel on HomeFragment?
I have a pretty straightforward case. I want to implement shared element transition between an item in recyclerView and fragment. I'm using android navigation component in my app.
There is an article about shared transition on developer.android and topic on stackoverflow but this solution works only for view that located in fragment layout that starts transition and doesn't work for items from RecyclerView. Also there is a lib on github but i don't want to rely on 3rd party libs and do it by myself.
Is there some solution for this? Maybe it should work and this is just a bug? But I haven't found any information about it.
code sample:
transition start
class TransitionStartFragment: Fragment() {
override fun onCreateView(inflater: LayoutInflater, container: ViewGroup?, savedInstanceState: Bundle?): View? {
return inflater.inflate(R.layout.fragment_transition_start, container, false)
}
override fun onViewCreated(view: View, savedInstanceState: Bundle?) {
super.onViewCreated(view, savedInstanceState)
val testData = listOf("one", "two", "three")
val adapter = TestAdapter(testData, View.OnClickListener { transitionWithTextViewInRecyclerViewItem(it) })
val recyclerView = view.findViewById<RecyclerView>(R.id.test_list)
recyclerView.adapter = adapter
val button = view.findViewById<Button>(R.id.open_transition_end_fragment)
button.setOnClickListener { transitionWithTextViewInFragment() }
}
private fun transitionWithTextViewInFragment(){
val destination = TransitionStartFragmentDirections.openTransitionEndFragment()
val extras = FragmentNavigatorExtras(transition_start_text to "transitionTextEnd")
findNavController().navigate(destination, extras)
}
private fun transitionWithTextViewInRecyclerViewItem(view: View){
val destination = TransitionStartFragmentDirections.openTransitionEndFragment()
val extras = FragmentNavigatorExtras(view to "transitionTextEnd")
findNavController().navigate(destination, extras)
}
}
layout
<androidx.constraintlayout.widget.ConstraintLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:app="http://schemas.android.com/apk/res-auto"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:orientation="vertical">
<TextView
android:id="#+id/transition_start_text"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="transition"
android:transitionName="transitionTextStart"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintTop_toTopOf="parent" />
<Button
android:id="#+id/open_transition_end_fragment"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
app:layout_constraintLeft_toLeftOf="parent"
app:layout_constraintTop_toBottomOf="#id/transition_start_text"
android:text="open transition end fragment" />
<androidx.recyclerview.widget.RecyclerView
android:id="#+id/test_list"
android:layout_width="match_parent"
android:layout_height="wrap_content"
app:layout_constraintTop_toBottomOf="#id/open_transition_end_fragment"
app:layout_constraintLeft_toLeftOf="parent"
app:layout_constraintBottom_toBottomOf="parent"
app:layoutManager="androidx.recyclerview.widget.LinearLayoutManager" />
adapter for recyclerView
class TestAdapter(
private val items: List<String>,
private val onItemClickListener: View.OnClickListener
) : RecyclerView.Adapter<TestAdapter.ViewHodler>() {
override fun onCreateViewHolder(parent: ViewGroup, viewType: Int): ViewHodler {
return ViewHodler(LayoutInflater.from(parent.context).inflate(R.layout.item_test, parent, false))
}
override fun getItemCount(): Int {
return items.size
}
override fun onBindViewHolder(holder: ViewHodler, position: Int) {
val item = items[position]
holder.transitionText.text = item
holder.itemView.setOnClickListener { onItemClickListener.onClick(holder.transitionText) }
}
class ViewHodler(itemView: View) : RecyclerView.ViewHolder(itemView) {
val transitionText = itemView.findViewById<TextView>(R.id.item_test_text)
}
}
in onItemClick I pass the textView form item in recyclerView for transition
transition end
class TransitionEndFragment : Fragment() {
override fun onCreateView(inflater: LayoutInflater, container: ViewGroup?, savedInstanceState: Bundle?): View? {
setUpTransition()
return inflater.inflate(R.layout.fragment_transition_end, container, false)
}
private fun setUpTransition(){
sharedElementEnterTransition = TransitionInflater.from(context).inflateTransition(android.R.transition.move)
}
}
layout
<androidx.constraintlayout.widget.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"
android:orientation="vertical">
<TextView
android:id="#+id/transition_end_text"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="transition"
android:transitionName="transitionTextEnd"
app:layout_constraintBottom_toBottomOf="parent"
app:layout_constraintEnd_toEndOf="parent" />
</androidx.constraintlayout.widget.ConstraintLayout>
fun transitionWithTextViewInFragment() - has transition.
fun transitionWithTextViewInRecyclerViewItem(view: View) - no transition.
To solve the return transition problem you need to add this lines on the Source Fragment (the fragment with the recycler view) where you initialize your recycler view
// your recyclerView
recyclerView.apply {
...
adapter = myAdapter
postponeEnterTransition()
viewTreeObserver
.addOnPreDrawListener {
startPostponedEnterTransition()
true
}
}
Here is my example with RecyclerView that have fragment shared transition.
In my adapter i am setting different transition name for each item based on position(In my example it is ImageView).
override fun onBindViewHolder(holder: ViewHolder, position: Int) {
val item = items[position]
holder.itemView.txtView.text=item
ViewCompat.setTransitionName(holder.itemView.imgViewIcon, "Test_$position")
holder.setClickListener(object : ViewHolder.ClickListener {
override fun onClick(v: View, position: Int) {
when (v.id) {
R.id.linearLayout -> listener.onClick(item, holder.itemView.imgViewIcon, position)
}
}
})
}
And when clicking on item, my interface that implemented in source fragment:
override fun onClick(text: String, img: ImageView, position: Int) {
val action = MainFragmentDirections.actionMainFragmentToSecondFragment(text, position)
val extras = FragmentNavigator.Extras.Builder()
.addSharedElement(img, ViewCompat.getTransitionName(img)!!)
.build()
NavHostFragment.findNavController(this#MainFragment).navigate(action, extras)
}
And in my destination fragment:
override fun onCreate(savedInstanceState: Bundle?) {
super.onCreate(savedInstanceState)
info("onCreate")
if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.LOLLIPOP) {
sharedElementEnterTransition = TransitionInflater.from(context).inflateTransition(android.R.transition.move)
}
}
override fun onCreateView(inflater: LayoutInflater, container: ViewGroup?, savedInstanceState: Bundle?): View? {
info("onCreateView")
return inflater.inflate(R.layout.fragment_second, container, false)
}
override fun onViewCreated(view: View, savedInstanceState: Bundle?) {
super.onViewCreated(view, savedInstanceState)
info("onViewCreated")
val name=SecondFragmentArgs.fromBundle(arguments).name
val position=SecondFragmentArgs.fromBundle(arguments).position
txtViewName.text=name
ViewCompat.setTransitionName(imgViewSecond, "Test_$position")
}
Faced the same issue as many on SO with the return transition but for me the root cause of the problem was that Navigation currently only uses replace for fragment transactions and it caused my recycler in the start fragment to reload every time you hit back which was a problem by itself.
So by solving the second (root) problem the return transition started to work without delayed animations. For those of you who are looking to keep the initial state when hitting back here is what I did :
just adding a simple check in onCreateView as so
private lateinit var binding: FragmentSearchResultsBinding
override fun onCreateView(
inflater: LayoutInflater,
container: ViewGroup?,
savedInstanceState: Bundle?
): View? {
return if (::binding.isInitialized) {
binding.root
} else {
binding = DataBindingUtil.inflate(inflater, R.layout.fragment_search_results, container, false)
with(binding) {
//doing some stuff here
root
}
}
So triple win here: recycler is not redrawn, no refetching from server and also return transitions are working as expected.
I have managed return transitions to work.
Actually this is not a bug in Android and not a problem with setReorderingAllowed = true. What happens here is the original fragment (to which we return) trying to start transition before its views/data are settled up.
To fix this we have to use postponeEnterTransition() and startPostponedEnterTransition().
For example:
Original fragment:
class FragmentOne : Fragment(R.layout.f1) {
override fun onViewCreated(view: View, savedInstanceState: Bundle?) {
super.onViewCreated(view, savedInstanceState)
postponeEnterTransition()
val items = listOf("one", "two", "three", "four", "five")
.zip(listOf(Color.RED, Color.GRAY, Color.GREEN, Color.BLUE, Color.YELLOW))
.map { Item(it.first, it.second) }
val rv = view.findViewById<RecyclerView>(R.id.rvItems)
rv.adapter = ItemsAdapter(items) { item, view -> navigateOn(item, view) }
view.doOnPreDraw { startPostponedEnterTransition() }
}
private fun navigateOn(item: Item, view: View) {
val extras = FragmentNavigatorExtras(view to "yura")
findNavController().navigate(FragmentOneDirections.toTwo(item), extras)
}
}
Next fragment:
class FragmentTwo : Fragment(R.layout.f2) {
val item: Item by lazy { arguments?.getSerializable("item") as Item }
override fun onViewCreated(view: View, savedInstanceState: Bundle?) {
super.onViewCreated(view, savedInstanceState)
sharedElementEnterTransition =
TransitionInflater.from(context).inflateTransition(android.R.transition.move)
val tv = view.findViewById<TextView>(R.id.tvItemId)
with(tv) {
text = item.id
transitionName = "yura"
setBackgroundColor(item.color)
}
}
}
For more details and deeper explanation see:
https://issuetracker.google.com/issues/118475573
and
https://chris.banes.dev/2018/02/18/fragmented-transitions/
Android material design library contains MaterialContainerTransform class which allows to easily implement container transitions including transitions on recycler-view items. See container transform section for more details.
Here's an example of such a transition:
// FooListFragment.kt
class FooListFragment : Fragment() {
...
private val itemListener = object : FooListener {
override fun onClick(item: Foo, itemView: View) {
...
val transitionName = getString(R.string.foo_details_transition_name)
val extras = FragmentNavigatorExtras(itemView to transitionName)
navController.navigate(directions, extras)
}
}
override fun onViewCreated(view: View, savedInstanceState: Bundle?) {
super.onViewCreated(view, savedInstanceState)
// Postpone enter transitions to allow shared element transitions to run.
// https://github.com/googlesamples/android-architecture-components/issues/495
postponeEnterTransition()
view.doOnPreDraw { startPostponedEnterTransition() }
...
}
// FooDetailsFragment.kt
class FooDetailsFragment : Fragment() {
...
override fun onCreate(savedInstanceState: Bundle?) {
super.onCreate(savedInstanceState)
sharedElementEnterTransition = MaterialContainerTransform().apply {
duration = 1000
}
}
}
And don't forget to add unique transition names to the views:
<!-- foo_list_item.xml -->
<LinearLayout ...
android:transitionName="#{#string/foo_item_transition_name(foo.id)}">...</LinearLayout>
<!-- fragment_foo_details.xml -->
<LinearLayout ...
android:transitionName="#string/foo_details_transition_name">...</LinearLayout>
<!-- strings.xml -->
<resources>
...
<string name="foo_item_transition_name" translatable="false">foo_item_transition_%1$s</string>
<string name="foo_details_transition_name" translatable="false">foo_details_transition</string>
</resources>
The full sample is available on GitHub.
You can also take a look at Reply - an official android material sample app where a similar transition is implemented, see HomeFragment.kt & EmailFragment.kt. There's a codelab describing the process of implementing transitions in the app, and a video tutorial.