设备旋转后，NavController 没有当前导航节点

Question

我正在制作支持不同设备方向的应用程序。导航由 Android Jetpack 的 Navigation 执行。横向应用程序主屏幕如下所示。它是列表包装片段（它是NavHostFragment，它被添加到fragment标签中的活动布局），包装包括列表片段（fragment）和详细信息片段（FrameLayout）。纵向方向是相似的（包装器和列表在其中，详细信息可访问抛出导航）。

我的问题是在更改设备方向后出现异常

java.lang.IllegalStateException: 没有当前导航节点

带有模拟数据的布局的第一个版本工作正常，在我将 ROOM 添加到我的应用程序、新订单和更新订单片段后出现错误。很遗憾，我无法更准确地定位错误源。

列出包装器代码

class OrderListWrapperFragment : RxFragment() {

    private val disposable = CompositeDisposable()

    var selectedOrderId: Long = 0

    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)

        val bundle = savedInstanceState ?: arguments
        bundle?.let {
            selectedOrderId = it.getLong(EXTRA_ORDER_ID)
        }
    }

    override fun onCreateView(
        inflater: LayoutInflater,
        container: ViewGroup?,
        savedInstanceState: Bundle?
    ): View? = inflater.inflate(R.layout.orders__list_wrapper, container, false)

    override fun onViewCreated(view: View, savedInstanceState: Bundle?) {
        super.onViewCreated(view, savedInstanceState)

        initializeToolbar(toolbar, getString(R.string.orders_title), false)

        newOrderButton
            .clicks()
            .subscribe {
                findNavController()
                    .navigate(R.id.action_orderListWrapperFragment_to_orderNewFragment)
            }
            .addTo(disposable)

        childFragmentManager.registerFragmentLifecycleCallbacks(callback, false)
    }

    override fun onDestroyView() {
        super.onDestroyView()

        childFragmentManager.unregisterFragmentLifecycleCallbacks(callback)

        disposable.clear()
    }

    override fun onSaveInstanceState(outState: Bundle) {
        super.onSaveInstanceState(outState)

        outState.putLong(EXTRA_ORDER_ID, selectedOrderId)
    }

    private val callback = object : FragmentManager.FragmentLifecycleCallbacks() {

        private val disposable = CompositeDisposable()

        override fun onFragmentResumed(fm: FragmentManager, fragment: Fragment) {
            super.onFragmentResumed(fm, fragment)

            if (fragment is OrderListFragment) {
                fragment
                    .selectedItemIdChanges
                    .subscribeBy(onNext = {
                        selectedOrderId = it
                        if (orderDetailsContainer != null) {
                            childFragmentManager.commit {
                                replace(
                                    R.id.orderDetailsContainer,
                                    OrderDetailsFragment.newInstance(it)
                                )
                            }
                        } else {
                            findNavController()
                                .navigate(
                                    R.id.action_orderListWrapperFragment_to_orderDetailsFragment,
                                    bundleOf(EXTRA_ORDER_ID to it)
                                )
                            selectedOrderId = 0
                        }
                    },
                        onError = {
                            Log.d("detailView", it.toString())
                        })
                    .addTo(disposable)

                val orderId = selectedOrderId
                if (orderId != 0L) {
                    if (orderDetailsContainer != null) {
                        childFragmentManager.commit {
                            replace(
                                R.id.orderDetailsContainer,
                                OrderDetailsFragment.newInstance(orderId)
                            )
                        }
                    } else {
                        findNavController()
                            .navigate(//exception throws here
                                R.id.action_orderListWrapperFragment_to_orderDetailsFragment,
                                bundleOf(EXTRA_ORDER_ID to orderId)
                            )
                        selectedOrderId = 0
                    }
                }
            }
        }

        override fun onFragmentPaused(fm: FragmentManager, fragment: Fragment) {
            super.onFragmentPaused(fm, fragment)

            if (fragment is OrderListFragment) {
                disposable.clear()
            }
        }
    }

    companion object {
        private const val EXTRA_ORDER_ID = "EXTRA_ORDER_ID"
    }
}

我的导航图

<?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/navigation_graph"
    app:startDestination="@id/orderListWrapperFragment">

    <fragment
        android:id="@+id/orderListWrapperFragment"
        android:name="com.mtgshipping.app.orders.orderList.OrderListWrapperFragment"
        android:label="OrderListWrapperFragment"
        tools:layout="@layout/orders__list_wrapper">
        <action
            android:id="@+id/action_orderListWrapperFragment_to_orderDetailsFragment"
            app:destination="@id/orderDetailsFragment"/>
        <action
            android:id="@+id/action_orderListWrapperFragment_to_orderNewFragment"
            app:destination="@id/orderNewFragment"/>
        <action
            android:id="@+id/action_orderListWrapperFragment_to_orderUpdateFragment"
            app:destination="@id/orderUpdateFragment"/>
    </fragment>

    <fragment
        android:id="@+id/orderDetailsFragment"
        android:name="com.mtgshipping.app.orders.orderDetails.OrderDetailsFragment"
        android:label="OrderDetailsFragment"
        tools:layout="@layout/orders__order_details">
        <action
            android:id="@+id/action_orderDetailsFragment_to_orderUpdateFragment"
            app:destination="@id/orderUpdateFragment"/>
    </fragment>

    <fragment
        android:id="@+id/orderNewFragment"
        android:name="com.mtgshipping.app.orders.orderNew.OrderNewFragment"
        android:label="OrderNewFragment"
        tools:layout="@layout/orders__order_new">
        <action
            android:id="@+id/action_orderNewFragment_to_orderListWrapperFragment"
            app:destination="@id/orderListWrapperFragment"/>
    </fragment>

    <fragment
        android:id="@+id/orderUpdateFragment"
        android:name="com.mtgshipping.app.orders.orderUpdate.OrderUpdateFragment"
        android:label="OrderUpdateFragment"
        tools:layout="@layout/orders__order_update">
        <action
            android:id="@+id/action_orderUpdateFragment_to_orderListWrapperFragment"
            app:destination="@id/orderListWrapperFragment"/>
    </fragment>
</navigation>

我在做一些调试NavController，这表明在线路746NavDestination currentNode = mBackStack.isEmpty() ? mGraph : mBackStack.getLast().getDestination();设备旋转后mGraph的null，其他私人领域也是null。也许有些东西阻止NavController了正确初始化。如果需要，我可以提供布局和其他代码。

Answer 1

感谢 Slav 的评论，他是对的。我navigation_version = '2.2.0'在应用程序的模块中将导航模块更新为 2.2.0build.gradle

implementation "androidx.navigation:navigation-fragment-ktx:$navigation_version"
implementation "androidx.navigation:navigation-ui-ktx:$navigation_version"

做完之后就不再出现这个问题了，貌似是导航的bug。

Answer 2

你也可以像这样修复它。在清单中的主机活动中添加此属性：

<activity android:name=".MainActivity"
        android:configChanges="orientation|screenSize|smallestScreenSize|screenLayout"

但最好的方法是更改​​导航依赖项：

implementation "android.arch.navigation:navigation-fragment-ktx:$navigation_version"
implementation "android.arch.navigation:navigation-ui-ktx:$navigation_version"

到

implementation "androidx.navigation:navigation-fragment-ktx:$nav_version"
implementation "androidx.navigation:navigation-ui-ktx:$nav_version"