我刚刚用Android导航组件建立了一个项目，下面是我的图的结构：
<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_graph"
app:startDestination="@id/a">
<fragment
android:id="@+id/a"
android:name="com.example.tutorial.fragmentA"
android:label="a">
<action android:id="@+id/action_a_to_b"
app:destination="@id/b"
app:enterAnim="@anim/nav_default_enter_anim"
app:exitAnim="@anim/nav_default_exit_anim"
app:popEnterAnim="@anim/nav_default_pop_enter_anim"
app:popExitAnim="@anim/nav_default_pop_exit_anim"/>
</fragment>
<fragment
android:id="@+id/b"
android:name="com.example.tutorial.fragmentB"
android:label="b">
</fragment>
</navigation>
在片段A中，我这样导航到B：
findNavController().navigate(R.id.action_a_to_b)
在片段B中，我有一个自定义工具栏，其想法是点击左上箭头应该关闭片段B并继续a:
(activity as AppCompatActivity).setSupportActionBar(binding.toolbar)
binding.toolbar.setNavigationOnClickListener {
findNavController().popBackStack()
}
如果我点击按下键的按钮也是一样的：
requireActivity().onBackPressedDispatcher.addCallback(viewLifecycleOwner){
findNavController().popBackStack()
}
我仍然被困在片段B中的问题是：退出动画开始和结束，我仍然在片段B。有什么想法可以解决这个问题吗？
我创建了一个包含2个片段的小项目，它可以流畅地工作。我们有一个登录屏幕和一个带密码的屏幕。
登录碎片
class LoginFragment : Fragment() {
override fun onCreateView(
inflater: LayoutInflater,
container: ViewGroup?,
savedInstanceState: Bundle?
): View? {
return inflater.inflate(R.layout.fragment_login, container, false)
}
override fun onViewCreated(view: View, savedInstanceState: Bundle?) {
super.onViewCreated(view, savedInstanceState)
val toolbar = view.findViewById<androidx.appcompat.widget.Toolbar>(R.id.loginToolbar)
toolbar.navigationIcon = null
// Set the Toolbar as your activity's ActionBar
(requireActivity() as AppCompatActivity).setSupportActionBar(toolbar)
// Find this Fragment's NavController
val navController = NavHostFragment.findNavController(this);
// And set up the ActionBar
NavigationUI.setupActionBarWithNavController(
requireActivity() as AppCompatActivity,
navController
)
val b = view.findViewById<MaterialButton>(R.id.loginButton)
b.setOnClickListener {
this.findNavController().navigate(R.id.passwordsFragment)
}
}
}
密码片段
class PasswordsFragment : Fragment() {
override fun onCreateView(
inflater: LayoutInflater,
container: ViewGroup?,
savedInstanceState: Bundle?
): View? {
return inflater.inflate(R.layout.fragment_passwords, container, false)
}
override fun onViewCreated(view: View, savedInstanceState: Bundle?) {
super.onViewCreated(view, savedInstanceState)
val toolbar = view.findViewById<androidx.appcompat.widget.Toolbar>(R.id.myToolbar)
// Set the Toolbar as your activity's ActionBar
(requireActivity() as AppCompatActivity).setSupportActionBar(toolbar)
// Find this Fragment's NavController
val navController = NavHostFragment.findNavController(this);
// And set up the ActionBar
NavigationUI.setupActionBarWithNavController(
requireActivity() as AppCompatActivity,
navController
)
toolbar.setNavigationOnClickListener {
navController.navigateUp()
}
}
}
登录碎片XML 中的工具栏
<androidx.appcompat.widget.Toolbar
android:id="@+id/loginToolbar"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:background="@color/black"
app:layout_constraintTop_toTopOf="parent" />
PasswordFragment XML 中的工具栏
<androidx.appcompat.widget.Toolbar
android:id="@+id/myToolbar"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:background="@color/black"
app:layout_constraintTop_toTopOf="parent" />
主活动XML
<androidx.constraintlayout.widget.ConstraintLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:app="http://schemas.android.com/apk/res-auto"
android:id="@+id/constraintLayout3"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:elevation="6dp"
android:fillViewport="true"
android:orientation="vertical">
<androidx.fragment.app.FragmentContainerView
android:id="@+id/my_nav_host_fragment"
android:name="androidx.navigation.fragment.NavHostFragment"
android:layout_width="0dp"
android:layout_height="0dp"
app:defaultNavHost="true"
app:layout_constraintBottom_toBottomOf="parent"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintTop_toTopOf="parent"
app:navGraph="@navigation/nav_graph" />
</androidx.constraintlayout.widget.ConstraintLayout>
我从loginFragment导航到PasswordFragment，然后按下向上按钮，进入上一个片段：(
让我知道它是否有效
private lateinit var appBarConfiguration: AppBarConfiguration
//onCreate
val navHostFragment =
supportFragmentManager.findFragmentById(R.id.fragment4) as NavHostFragment
val navController = navHostFragment.navController
appBarConfiguration = AppBarConfiguration(navController.graph, drawerLayout)
setupActionBarWithNavController(navController, appBarConfiguration)
navDrawView.setupWithNavController(navController)
bottomAppBar.background = null
bottomAppBar.setupWithNavController(navController)
//automatic NavigateUp setup
override fun onSupportNavigateUp(): Boolean {
val navController = findNavController(R.id.fragment4)
return navController.navigateUp(appBarConfiguration)
|| super.onSupportNavigateUp()
}
你能在你的主要活动中尝试一下这个设置吗？它对我很有效，我把bottomNav导航抽屉和appbar一起使用。
如果你想使用自定义工具栏
//in fragment or activity
private fun handleToolbarChanges() {
with(binding.toolbarDataAnalysis) {
setNavigationOnClickListener { onBackPressed() }
title = "your title here"
}
}
//in xml file
<androidx.appcompat.widget.Toolbar
android:id="@+id/toolbarDataAnalysis"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:background="@color/green"
app:navigationIcon="@drawable/ic_baseline_arrow_back_24"
app:titleTextColor="@color/white" />
现在我们可以使用popBackStack((为第二个片段的返回值创建观测器
假设我们有第一片段和第二片段
在firstFragment中，将其用于观察者：-
override fun onViewCreated(view: View, savedInstanceState: Bundle?) {
super.onViewCreated(view, savedInstanceState)
val navController = findNavController()
navController.currentBackStackEntry?.savedStateHandle?.getLiveData<String>("isDelete")
?.observe(viewLifecycleOwner) {
if(it.lowercase().compareTo("true")==0)
{
//write code here
}
else
{
//write code here
}
}
}
在secondFragment中使用此代码
val navController = findNavController()
navController.previousBackStackEntry?.savedStateHandle?.set("isDelete", "true/false")
navController.popBackStack()