android - popBackStack() 在 android NavController 中不起作用

Question

我正在使用 android JetPack 导航在我的 fragment 之间导航。这就是我的navigation graph好像

 <?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/registration_nav_graph"
app:startDestination="@id/registrationStoreNameFragment">

<fragment
    android:id="@+id/registrationStoreNameFragment"
    android:name="com.minidukaan.android.feature.registration.view.RegistrationStoreNameFragment"
    android:label="fragment_registration_store_name"
    tools:layout="@layout/fragment_registration_store_name" >
    <action
        android:id="@+id/action_registrationStoreNameFragment_to_registrationStoreUrlFragment2"
        app:destination="@id/registrationStoreUrlFragment2" />
</fragment>

<fragment
    android:id="@+id/registrationStoreUrlFragment2"
    android:name="com.minidukaan.android.feature.registration.view.RegistrationStoreUrlFragment"
    android:label="RegistrationStoreUrlFragment" >
    <action
        android:id="@+id/action_registrationStoreUrlFragment2_to_registrationLocationFragment"
        app:destination="@id/registrationLocationFragment" />
    <argument
        android:name="store_name"
        app:argType="string" />
    <argument
        android:name="store_slug"
        app:argType="string" />
</fragment>


<fragment
    android:id="@+id/registrationLocationFragment"
    android:name="com.minidukaan.android.feature.registration.view.RegistrationLocationFragment"
    android:label="fragment_registration_location"
    tools:layout="@layout/fragment_registration_location" >
    <action
        android:id="@+id/action_registrationLocationFragment_to_registrationSuccessFragment"
        app:destination="@id/registrationSuccessFragment" />
    <argument
        android:name="store_name"
        app:argType="string" />
    <argument
        android:name="store_slug"
        app:argType="string"
        android:defaultValue=""/>
</fragment>
<fragment
    android:id="@+id/registrationSuccessFragment"
    android:name="com.minidukaan.android.feature.registration.view.RegistrationSuccessFragment"
    android:label="fragment_registration_success"
    tools:layout="@layout/fragment_registration_success" />

来自 RegistrationStoreNameFragment我导航到 RegistrationStoreUrlFragment像这样

private lateinit var navController: NavController
override fun init(savedInstanceState: Bundle?) {
    super.init(savedInstanceState)
    ....

    binding.lifecycleOwner = this
    navController = view?.let { Navigation.findNavController(it) }!!
    val action = RegistrationStoreNameFragmentDirections.
                        actionRegistrationStoreNameFragmentToRegistrationStoreUrlFragment2(storeName, it.slug)
                            navController.navigate(action)

}
所以它可以完美导航，但是当我这样做时 navController.popBackStack()在 RegistrationStoreUrlFragment然后它不会导航回来。任何帮助都将受到高度赞赏，因为我在这个问题上停留了很长时间。
对于其他 fragment ，popBackStack 工作正常，但不适用于上面提到的 fragment 。

Answer 1

你想什么时候导航？
如果在任何自定义事件上您想导航回之前添加的 fragment ，那么，
您必须定义 弹出到 在您的 下采取行动 fragment 标记 导航图 ,

<fragment
android:id="@+id/registrationStoreUrlFragment2"
android:name="com.minidukaan.android.feature.registration.view.RegistrationStoreUrlFragment"
android:label="RegistrationStoreUrlFragment" >
<action
        android:id="@+id/action_pop_back"
        app:destination="@id/registrationSuccessFragment"
        app:popUpTo="@+id/registrationSuccessFragment"/>
</fragment>

并像这样在导航中调用它，

findNavController().navigate(R.id.action_pop_back)