多くのフラグメントを持つ単一のアクティビティがあります (ジェットパック ナビゲーションを使用)。私の最初のフラグメントには、リサイクルビューがあります。最初のフラグメントをスクロールしてから別のフラグメントに移動すると、フラグメントはスクロール位置を保持し、それは望ましくありません。例は次のとおりです。
つまり、A と B の 2 つのフラグメントがあるとします。アプリを開始すると、A で開始されます。A でスクロールを開始してから B に移動するとします。フラグメント B を上から開始したい。そして、フラグメントAに戻ったときに、以前にスクロールしたスクロール位置を保持したい.
フラグメント A.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">
<data>
<import type="android.view.View" />
<variable
name="ViewModel"
type="....AccountViewModel" />
</data>
<androidx.constraintlayout.widget.ConstraintLayout
android:id="@+id/Layout_Fragment_Account"
android:layout_width="match_parent"
android:layout_height="match_parent">
<!--
Recyclerview
-->
<androidx.recyclerview.widget.RecyclerView
android:id="@+id/RecyclerView_Account"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:visibility="@{ViewModel.accountListVisibility? View.VISIBLE : View.GONE}"
app:layoutManager="androidx.recyclerview.widget.LinearLayoutManager"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintTop_toTopOf="parent"
tools:visibility="gone" />
<!--
Empty Views and group
-->
<androidx.constraintlayout.widget.Group
android:id="@+id/Empty_View"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:visibility="@{ViewModel.accountEmptyViewVisibility?
View.VISIBLE : View.GONE}"
app:constraint_referenced_ids="Empty_View_Illustration,Empty_View_Title,Empty_View_Subtitle" />
<ImageView
android:id="@+id/Empty_View_Illustration"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_gravity="center_horizontal"
android:scaleType="centerCrop"
app:layout_constraintBottom_toTopOf="@+id/Empty_View_Title"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintTop_toTopOf="parent"
app:layout_constraintVertical_chainStyle="packed"
app:srcCompat="@drawable/il_account" />
<TextView
android:id="@+id/Empty_View_Title"
style="@style/Locky.Text.Title6"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:layout_marginStart="32dp"
android:layout_marginEnd="32dp"
android:text="@string/text_title_emptyView_accounts"
android:textAlignment="center"
app:layout_constraintBottom_toTopOf="@id/Empty_View_Subtitle"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintTop_toBottomOf="@+id/Empty_View_Illustration"
app:layout_constraintVertical_chainStyle="packed"
app:layout_constraintWidth_default="percent"
app:layout_constraintWidth_percent=".8" />
<TextView
android:id="@+id/Empty_View_Subtitle"
style="@style/Locky.Text.Subtitle"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:layout_gravity="center_horizontal"
android:layout_marginStart="32dp"
android:layout_marginEnd="32dp"
android:layout_marginBottom="?attr/actionBarSize"
android:text="@string/text_subtitle_emptyView_accounts"
android:textAlignment="center"
app:layout_constraintBottom_toBottomOf="parent"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintHorizontal_bias="0.6"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintTop_toBottomOf="@+id/Empty_View_Title"
app:layout_constraintWidth_default="percent"
app:layout_constraintWidth_percent=".8" />
<!--
Progress Bar
-->
<include
android:id="@+id/Progress_Bar"
layout="@layout/custom_view_list_loading"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:visibility="@{ViewModel.loadingStatus? View.VISIBLE : View.GONE}"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintTop_toTopOf="parent" />
</androidx.constraintlayout.widget.ConstraintLayout>
</layout>
フラグメント A.kt:
class AccountFragment : Fragment() {
private var _binding: FragmentAccountBinding? = null
private var _viewModel: AccountViewModel? = null
private var _lastClickTime: Long = 0
private val binding get() = _binding!!
private val viewModel get() = _viewModel!!
companion object {
const val TAG = "ACCOUNT_FRAGMENT_DEBUG"
}
override fun onCreateView(
inflater: LayoutInflater,
container: ViewGroup?,
savedInstanceState: Bundle?
): View? {
// Inflate the layout for this fragment
_binding = FragmentAccountBinding.inflate(inflater, container, false)
// Fetch view model
_viewModel = ViewModelProvider(this).get(AccountViewModel::class.java)
//Bind view model to layout
binding.viewModel = _viewModel
// Bind lifecycle owner
binding.lifecycleOwner = this
return binding.root
}
override fun onViewCreated(view: View, savedInstanceState: Bundle?) {
super.onViewCreated(view, savedInstanceState)
/* Hides the soft keyboard */
hideSoftKeyboard(binding.root)
/* Observe snack bar events */
observeSnackBarEvent()
/* Observe the account list changes */
observeAccounts()
/* Observe back stack entry result after navigating from sort sheet */
observeBackStackEntryForSortSheet()
}
override fun onCreate(savedInstanceState: Bundle?) {
super.onCreate(savedInstanceState)
setHasOptionsMenu(true)
}
override fun onCreateOptionsMenu(menu: Menu, inflater: MenuInflater) {
inflater.inflate(R.menu.menu_toolbar_filter, menu)
super.onCreateOptionsMenu(menu, inflater)
}
override fun onOptionsItemSelected(item: MenuItem): Boolean {
return when (item.itemId) {
R.id.Toolbar_Filter -> {
navigateToSort()
true
}
else -> false
}
}
override fun onDestroyView() {
super.onDestroyView()
_binding = null
}
/*
* My Functions
*/
private fun observeBackStackEntryForSortSheet() {
val navController = findNavController()
// After a configuration change or process death, the currentBackStackEntry
// points to the dialog destination, so you must use getBackStackEntry()
// with the specific ID of your destination to ensure we always
// get the right NavBackStackEntry
val navBackStackEntry = navController.getBackStackEntry(R.id.Fragment_Account)
// Create our observer and add it to the NavBackStackEntry's lifecycle
val observer = LifecycleEventObserver { _, event ->
if (event == Lifecycle.Event.ON_RESUME
&& navBackStackEntry.savedStateHandle.contains(KEY_ACCOUNTS_SORT)
) {
viewModel.sortChange(
navBackStackEntry.savedStateHandle.get<AccountSort>(
KEY_ACCOUNTS_SORT
)!!
)
navBackStackEntry.savedStateHandle.remove<AccountSort>(KEY_ACCOUNTS_SORT)
}
}
navBackStackEntry.lifecycle.addObserver(observer)
// As addObserver() does not automatically remove the observer, we
// call removeObserver() manually when the view lifecycle is destroyed
viewLifecycleOwner.lifecycle.addObserver(LifecycleEventObserver { _, event ->
if (event == Lifecycle.Event.ON_DESTROY) {
navBackStackEntry.lifecycle.removeObserver(observer)
}
})
}
private fun observeSnackBarEvent() {
viewModel.showSnackBarEvent.observe(viewLifecycleOwner, Observer {
if (it != null) {
snackBarAction(it)
}
})
}
private fun observeAccounts() {
with(viewModel) {
accounts.observe(viewLifecycleOwner, Observer {
if (it != null) {
//set loading flag to hide loading animation
doneLoading()
//Alternate visibility for account list and empty view
alternateAccountListVisibility(it.size)
//Submit the cards
initiateAccounts().submitList(it)
}
})
}
}
private fun initiateAccounts(): AccountAdapter {
val adapter = AccountAdapter(
AccountClickListener {
navigateToSelectedAccount(it)
},
AccountOptionsClickListener { view, card ->
view.apply {
isEnabled = false
}
createPopupMenu(view, card)
})
binding.RecyclerViewAccount.apply {
this.adapter = adapter
setHasFixedSize(true)
}
return adapter
}
private fun createPopupMenu(view: View, account: Account) {
requireContext().createPopUpMenu(
view,
R.menu.menu_moreoptions_account,
PopupMenu.OnMenuItemClickListener {
when (it.itemId) {
R.id.Menu_CopyUsername -> copyToClipboardAndToast(account.username)
R.id.Menu_CopyPass -> copyToClipboardAndToast(account.password)
R.id.Menu_ShowPass -> triggerSnackBarEvent(account.password)
else -> false
}
}, PopupMenu.OnDismissListener {
view.apply {
isEnabled = true
}
})
}
private fun navigateToSort() {
if (SystemClock.elapsedRealtime() - _lastClickTime >= 800) {
_lastClickTime = SystemClock.elapsedRealtime()
navigateTo(AccountFragmentDirections.actionFragmentAccountToBottomSheetFragmentAccountFilter())
}
}
private fun navigateToSelectedAccount(account: Account) {
navigateTo(
AccountFragmentDirections.actionFragmentAccountToFragmentViewAccount(
account
)
)
}
private fun snackBarAction(message: String) {
binding.LayoutFragmentAccount.snackbar(message) {
action(getString(R.string.button_snack_action_close)) { dismiss() }
}
viewModel.doneShowingSnackBar()
}
private fun triggerSnackBarEvent(message: String): Boolean {
viewModel.setSnackBarMessage(message)
return true
}
private fun copyToClipboardAndToast(message: String): Boolean {
copyToClipboard(message)
toast(getString(R.string.message_copy_successful))
return true
}
フラグメント B.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">
<data>
<variable
name="Account"
type="....Account" />
</data>
<androidx.constraintlayout.widget.ConstraintLayout
android:id="@+id/Layout_Credential_View"
android:layout_width="match_parent"
android:layout_height="match_parent">
<ImageView
android:id="@+id/Account_Logo"
imageUrl="@{Account.logoUrl}"
loadingResource="@{@drawable/ic_image_loading}"
errorResource="@{@drawable/ic_account_placeholder}"
android:layout_width="100dp"
android:layout_height="100dp"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintTop_toTopOf="parent"
tools:src="@drawable/ic_account_placeholder" />
<TextView
android:id="@+id/Account_Name"
style="@style/Locky.Text.Title5.Name"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:layout_marginStart="32dp"
android:layout_marginTop="16dp"
android:layout_marginEnd="32dp"
android:textAlignment="center"
android:text="@{Account.accountName}"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintTop_toBottomOf="@+id/Account_Logo"
tools:text="This can be a very very very long title toooooo" />
<androidx.recyclerview.widget.RecyclerView
android:id="@+id/RecyclerView_Credentials_Field"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:layout_marginStart="8dp"
android:layout_marginTop="24dp"
android:layout_marginEnd="8dp"
android:nestedScrollingEnabled="true"
app:layoutManager="androidx.recyclerview.widget.LinearLayoutManager"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintTop_toBottomOf="@+id/Account_Name" />
</androidx.constraintlayout.widget.ConstraintLayout>
</layout>
フラグメント B.kt
class ViewAccountFragment : Fragment() {
private var _binding: FragmentViewAccountBinding? = null
private var _viewModel: ViewAccountViewModel? = null
private lateinit var _account: Account
private val binding get() = _binding!!
private val viewModel get() = _viewModel!!
override fun onCreateView(
inflater: LayoutInflater,
container: ViewGroup?,
savedInstanceState: Bundle?
): View? {
//Fetch the layout and do the binding
_binding = FragmentViewAccountBinding.inflate(inflater, container, false)
//Instantiate view model
_viewModel = ViewModelProvider(this).get(ViewAccountViewModel::class.java)
binding.lifecycleOwner = this
//Fetch the account clicked on the previous screen
_account = ViewAccountFragmentArgs.fromBundle(requireArguments()).parcelcredaccount
with(_account) {
//Bind the account to the layout for displaying
binding.account = this
//Submit the account details to the recyclerview
initiateCredentialsFieldList().submitList(viewModel.fieldList(this))
}
return binding.root
}
override fun onViewCreated(view: View, savedInstanceState: Bundle?) {
super.onViewCreated(view, savedInstanceState)
/* Hides the soft keyboard */
hideSoftKeyboard(binding.root)
}
override fun onDestroyView() {
super.onDestroyView()
_binding = null
}
override fun onCreate(savedInstanceState: Bundle?) {
super.onCreate(savedInstanceState)
setHasOptionsMenu(true)
}
override fun onCreateOptionsMenu(menu: Menu, inflater: MenuInflater) {
inflater.inflate(R.menu.menu_credentials_actions, menu)
super.onCreateOptionsMenu(menu, inflater)
}
override fun onOptionsItemSelected(item: MenuItem): Boolean {
return when (item.itemId) {
R.id.Action_Duplicate -> {
/*
* We set the account id to empty here
* When the add screen receives it, it wil perceive it as a new account that needs to be
* added to the database
*/
navigateToEditScreen(_account.copy(accountID = generateUniqueID()))
true
}
R.id.Action_Edit -> {
navigateToEditScreen(_account)
true
}
R.id.Action_Delete -> {
deleteConfirmationDialog(_account.accountName)
true
}
else -> false
}
}
private fun initiateCredentialsFieldList(): CredentialsViewAdapter {
val credentialsAdapter =
CredentialsViewAdapter(
CopyClickListener { data ->
copyToClipboardAndToast(data)
},
ViewClickListener { data ->
snackBarAction(data)
})
binding.RecyclerViewCredentialsField.apply {
adapter = credentialsAdapter
setHasFixedSize(true)
}
return credentialsAdapter
}
private fun deleteAndNavigateBackToAccountList() {
with(_account) {
viewModel.delete(accountID)
toast(getString(R.string.message_credentials_deleted, accountName))
findNavController().popBackStack()
}
}
ナビゲーション.xml
<fragment
android:id="@+id/Fragment_Account"
android:name="....AccountFragment"
android:label="Accounts"
tools:layout="@layout/fragment_account">
<action
android:id="@+id/action_Fragment_Account_to_Fragment_View_Account"
app:destination="@id/Fragment_View_Account" />
<action
android:id="@+id/action_Fragment_Account_to_BottomSheet_Fragment_Account_Filter"
app:destination="@id/BottomSheet_Fragment_Account_Filter" />
</fragment>
MainActivity.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.drawerlayout.widget.DrawerLayout
android:id="@+id/Drawer_Main"
android:layout_width="match_parent"
android:layout_height="match_parent"
tools:context=".ui.main.main.MainActivity">
<androidx.coordinatorlayout.widget.CoordinatorLayout
android:id="@+id/Layout_Coordinator_Main"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:fitsSystemWindows="true">
<com.google.android.material.appbar.MaterialToolbar
android:id="@+id/Toolbar_Main"
android:layout_width="match_parent"
android:layout_height="?attr/actionBarSize"
android:background="@color/colorOnSurface"
android:outlineAmbientShadowColor="@color/colorShadowColor"
android:outlineSpotShadowColor="@color/colorShadowColor">
<TextView
android:id="@+id/Toolbar_Main_Title"
style="@style/Locky.Text.Title6.Toolbar"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_gravity="center"
android:text="@string/app_name" />
</com.google.android.material.appbar.MaterialToolbar>
<androidx.core.widget.NestedScrollView
android:id="@+id/Nested_Scroll"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:layout_marginTop="?attr/actionBarSize"
android:fillViewport="true">
<fragment
android:id="@+id/Navigation_Host"
android:name="androidx.navigation.fragment.NavHostFragment"
android:layout_width="match_parent"
android:layout_height="match_parent"
app:defaultNavHost="true"
app:navGraph="@navigation/navigation_drawer_main" />
</androidx.core.widget.NestedScrollView>
<com.google.android.material.floatingactionbutton.FloatingActionButton
android:id="@+id/FAB_Search"
style="@style/Locky.FloatingActionButton.Mini"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_marginTop="0dp"
android:layout_marginBottom="85dp"
app:layout_anchor="@id/FAB_Add"
app:layout_anchorGravity="top|center_horizontal"
app:layout_behavior="com.google.android.material.behavior.HideBottomViewOnScrollBehavior"
app:srcCompat="@drawable/ic_search" />
<com.google.android.material.floatingactionbutton.FloatingActionButton
android:id="@+id/FAB_Add"
style="@style/Locky.FloatingActionButton.Normal"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_gravity="bottom|end"
android:layout_margin="@dimen/fab_margin"
app:layout_behavior="com.google.android.material.behavior.HideBottomViewOnScrollBehavior"
app:srcCompat="@drawable/ic_add" />
</androidx.coordinatorlayout.widget.CoordinatorLayout>
<com.google.android.material.navigation.NavigationView
android:id="@+id/Navigation_View"
style="@style/Locky.Widget.Custom.NavigationView"
android:layout_width="280dp"
android:layout_height="match_parent"
android:layout_gravity="start"
android:clipToPadding="false"
android:paddingStart="0dp"
android:paddingEnd="16dp"
app:headerLayout="@layout/drawer_header"
app:itemTextAppearance="@style/Locky.Text.Body.Drawer"
app:menu="@menu/menu_drawer_main" />
</androidx.drawerlayout.widget.DrawerLayout>
MainActivity.kt
class MainActivity : AppCompatActivity() {
private lateinit var _binding: ActivityMainBinding
private lateinit var _viewModel: MainActivityViewModel
private lateinit var _appBarConfiguration: AppBarConfiguration
//Fragments that can navigate with the drawer
private val _navigationFragments = setOf(
R.id.Fragment_Card,
R.id.Fragment_Account,
R.id.Fragment_Device
)
override fun onCreate(savedInstanceState: Bundle?) {
super.onCreate(savedInstanceState)
_binding = DataBindingUtil.setContentView(this, R.layout.activity_main)
_viewModel = ViewModelProvider(this).get(MainActivityViewModel::class.java)
_binding.lifecycleOwner = this
//Set the support action bar to the toolbar
setSupportActionBar(_binding.ToolbarMain)
//Remove the default actionbar title
supportActionBar?.setDisplayShowTitleEnabled(false)
/* Updates the app settings*/
updateAppSettings()
//Setup the navigation components
navigationUISetup()
//Load FABs
listenerForAddFab()
listenerForSearchFab()
//Scroll changes to adjust toolbar elevation accordingly
setUpNestedScrollChangeListener()
}
override fun onOptionsItemSelected(item: MenuItem) =
item.onNavDestinationSelected(findNavController(R.id.Navigation_Host)) || super.onOptionsItemSelected(
item
)
override fun onSupportNavigateUp() =
findNavController(R.id.Navigation_Host).navigateUp(_appBarConfiguration)
override fun finish() {
super.finish()
ActivityNavigator.applyPopAnimationsToPendingTransition(this)
}
private fun navigationUISetup() {
//Fetch the Nav Controller
val navController = findNavController(R.id.Navigation_Host)
//Setup the App Bar Configuration
_appBarConfiguration = AppBarConfiguration(_navigationFragments, _binding.DrawerMain)
//Use Navigation UI to setup the app bar config and navigation view
NavigationUI.setupActionBarWithNavController(this, navController, _appBarConfiguration)
NavigationUI.setupWithNavController(_binding.NavigationView, navController)
//Set the mini FABs with navigation to navigate to fragments accordingly.
Navigation.setViewNavController(_binding.FABAdd, navController)
Navigation.setViewNavController(_binding.FABSearch, navController)
//Add on change destination listener to navigation controller to handle fab visibility
navigationDestinationChangeListener_FAB(navController)
//Add on change destination listener to navigation controller to handle screen title visibility
navigationDestinationChangeListener_ToolbarTitle(navController)
}
private fun setUpNestedScrollChangeListener() =
_binding.NestedScroll.setOnScrollChangeListener { _, _, scrollY, _, _ ->
if (scrollY > 0) {
_binding.ToolbarMain.elevation = 12F
} else {
_binding.ToolbarMain.elevation = 0F
}
}
private fun navigationDestinationChangeListener_ToolbarTitle(navController: NavController) {
navController.addOnDestinationChangedListener { _, nd, _ ->
when (nd.id) {
R.id.Fragment_Account -> updateToolbar(getString(R.string.text_title_screen_accounts))
R.id.Fragment_Card -> updateToolbar(getString(R.string.text_title_screen_cards))
R.id.Fragment_Device -> updateToolbar(getString(R.string.text_title_screen_devices))
R.id.Fragment_Settings -> updateToolbar(getString(R.string.text_title_screen_settings))
R.id.Fragment_Profile -> updateToolbar(getString(R.string.text_title_screen_profile))
R.id.Fragment_About -> updateToolbar(getString(R.string.text_title_screen_about))
R.id.Fragment_Donate -> updateToolbar(getString(R.string.text_title_screen_donate))
else -> {
//Show the toolbar
updateToolbar(null)
}
}
}
}
private fun navigationDestinationChangeListener_FAB(navController: NavController) {
navController.addOnDestinationChangedListener { nc, nd, _ ->
when (nd.id) {
nc.graph.startDestination,
R.id.Fragment_Card,
R.id.Fragment_Device -> {
_binding.DrawerMain.setDrawerLockMode(DrawerLayout.LOCK_MODE_UNLOCKED)
//Show all the FABs
showFABs()
}
else -> {
_binding.DrawerMain.setDrawerLockMode(DrawerLayout.LOCK_MODE_LOCKED_CLOSED)
//Hide all the FABs
hideFABs()
}
}
}
}
private fun getFadeNavOptions(): NavOptions? {
return NavOptions.Builder()
.setEnterAnim(R.anim.anim_fade_in)
.setExitAnim(R.anim.anim_fade_out)
.build()
}
private fun hideFABs() {
_binding.FABSearch.hide()
_binding.FABAdd.hide()
}
private fun showFABs() {
_binding.FABSearch.show()
_binding.FABAdd.show()
showFABFromSlidingBehavior(_binding.FABSearch, _binding.FABSearch.isVisible)
showFABFromSlidingBehavior(_binding.FABAdd, _binding.FABAdd.isVisible)
}
private fun showFABFromSlidingBehavior(fab: FloatingActionButton, isVisible: Boolean) {
val layoutParams: ViewGroup.LayoutParams = fab.layoutParams
if (layoutParams is CoordinatorLayout.LayoutParams) {
val behavior = layoutParams.behavior
if (behavior is HideBottomViewOnScrollBehavior) {
if (isVisible) {
behavior.slideUp(fab)
} else {
behavior.slideDown(fab)
}
}
}
}
ここで問題を示すためにgifを添付しました：
GIF では、3 つのフラグメント (フラグメント A > フラグメント B > フラグメント C) から移動します。ここで間違っていることはありますか?