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使用导航抽屉与导航架构组件

androidnavigation-drawerandroid-architecture-componentsandroid-architecture-navigation
6
我正在尝试使用导航架构组件（NavHostFragment）和导航抽屉（widget.NavigationView）。我遇到了以下两个错误之一。
1）当从抽屉中选择项目多次时可能会发生这种情况： java.lang.IllegalArgumentException: navigation destination app.myDomain.navdrawertrials:id/action_rootFragment_to_settingsFragment is unknown to this NavController 2）这是我的真实代码库，它与下面的简化示例设置方式相同。为什么当前导航节点没有被设置？ java.lang.IllegalStateException: no current navigation node 简化代码 MainActivity
class MainActivity : AppCompatActivity() {

    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)
        setContentView(R.layout.main_activity)

        setupToolbar()
        setupNavDrawer()
        setupNavigation()
    }


    private fun setupToolbar() {
        setSupportActionBar( toolbar )
    }

    private fun setupNavigation() {
        val navController = findNavController( R.id.nav_host_fragment)

        setupActionBarWithNavController( navController, main_activity_drawer_layout )
    }

    private fun setupNavDrawer() {
        val toggle = ActionBarDrawerToggle(
                this,
                main_activity_drawer_layout,
                toolbar,
                R.string.navigation_drawer_open,
                R.string.navigation_drawer_close)

        main_activity_drawer_layout.addDrawerListener(toggle)
        toggle.syncState()


        nav_drawer.setNavigationItemSelectedListener {
            val navController = findNavController( R.id.nav_host_fragment )

            when (it.itemId) {
                R.id.nav_drawer_root_menu_item     -> navController.navigate(R.id.rootFragment)
                R.id.nav_drawer_first_menu_item    -> navController.navigate(R.id.action_rootFragment_to_firstFragment)
                R.id.nav_drawer_settings_menu_item -> navController.navigate(R.id.action_rootFragment_to_settingsFragment)
            }

            main_activity_drawer_layout.closeDrawer(GravityCompat.START)

            true
        }
    }

    override fun onSupportNavigateUp() = findNavController(R.id.nav_host_fragment).navigateUp()
}

main_activity.xml

<android.support.v4.widget.DrawerLayout
    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_activity_drawer_layout"
    android:layout_width="match_parent"
    android:layout_height="match_parent">

    <include
        layout="@layout/main_activity_content"
        android:layout_width="match_parent"
        android:layout_height="match_parent" />

    <android.support.design.widget.NavigationView
        android:id="@+id/nav_drawer"
        android:layout_width="wrap_content"
        android:layout_height="match_parent"
        android:layout_gravity="start"
        android:fitsSystemWindows="true"
        app:headerLayout="@layout/nav_drawer_header"
        app:menu="@menu/nav_drawer_menu" />

</android.support.v4.widget.DrawerLayout>

nav_drawer_menu.xml

<menu xmlns:android="http://schemas.android.com/apk/res/android">

    <item
        android:id="@+id/nav_drawer_root_menu_item"
        android:title="To Root" />
    <item
        android:id="@+id/nav_drawer_first_menu_item"
        android:title="To First" />
    <item
        android:id="@+id/nav_drawer_settings_menu_item"
        android:title="To Settings" />
</menu>

main_activity_content.xml

<android.support.design.widget.CoordinatorLayout
    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"
    tools:context=".MainActivity">

    <android.support.design.widget.AppBarLayout
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:theme="@style/AppTheme">

        <android.support.v7.widget.Toolbar
            android:id="@+id/toolbar"
            android:layout_width="match_parent"
            android:layout_height="?attr/actionBarSize"
            android:background="?attr/colorPrimary" />

    </android.support.design.widget.AppBarLayout>

    <fragment
        android:id="@+id/nav_host_fragment"
        android:name="androidx.navigation.fragment.NavHostFragment"
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        app:navGraph="@navigation/nav_graph"
        app:defaultNavHost="true"
        />

    <android.support.design.widget.FloatingActionButton
        android:id="@+id/fab"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_gravity="bottom|end"
        android:layout_margin="@dimen/fab_margin"
        app:srcCompat="@android:drawable/ic_dialog_email" />

</android.support.design.widget.CoordinatorLayout>

nav_graph.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_graph"
    app:startDestination="@id/rootFragment">

    <fragment
        android:id="@+id/rootFragment"
        android:name="app.anytune.navdrawertrials.RootFragment"
        android:label="root_fragment"
        tools:layout="@layout/root_fragment" >
        <action
            android:id="@+id/action_rootFragment_to_firstFragment"
            app:destination="@id/firstFragment" />
        <action
            android:id="@+id/action_rootFragment_to_settingsFragment"
            app:destination="@id/settingsFragment" />
    </fragment>
    <fragment
        android:id="@+id/firstFragment"
        android:name="app.anytune.navdrawertrials.FirstFragment"
        android:label="first_fragment"
        tools:layout="@layout/first_fragment" />
    <fragment
        android:id="@+id/settingsFragment"
        android:name="app.anytune.navdrawertrials.SettingsFragment"
        android:label="settings_fragment"
        tools:layout="@layout/settings_fragment" />
</navigation>

root_fragment.xml（其他节点是类似的空片段，只有一个标签）

<FrameLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    tools:context=".RootFragment">

    <TextView
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        android:text="Root Fragment" />

</FrameLayout>
1
你知道如何解决第二个问题吗？java.lang.IllegalStateException: no current navigation node？ - RediOne1
1
这个错误发生时，您是否在旋转设备？ - IgorGanapolsky
2个回答
3
关于第一个错误，根据您的代码，在用户从抽屉中选择“first”或“settings”时，会使用action_rootFragment_to_firstFragment或action_rootFragment_to_settingsFragment操作将其转移到“first”或“settings”片段，但如果再次尝试从抽屉中选择“first”或“settings”，则在导航图中的firstFragment或settingsFragment元素中没有action_rootFragment_to_firstFragment或action_rootFragment_to_settingsFragment操作。
解决方法是更改：
when (it.itemId) { 
            R.id.nav_drawer_root_menu_item     -> navController.navigate(R.id.rootFragment) 
            R.id.nav_drawer_first_menu_item    -> navController.navigate(R.id.action_rootFragment_to_firstFragment) 
            R.id.nav_drawer_settings_menu_item -> navController.navigate(R.id.action_rootFragment_to_settingsFragment) 
        }

to:

   when (it.itemId) { 
            R.id.nav_drawer_root_menu_item     -> navController.navigate(R.id.rootFragment) 
            R.id.nav_drawer_first_menu_item    -> navController.navigate(R.id.firstFragment) 
            R.id.nav_drawer_settings_menu_item -> navController.navigate(R.id.settingsFragment) 
        }

更好的解决方案是将目的地与菜单驱动的UI组件（在您的情况下为抽屉）绑定，将菜单项id更改为与目的地id相同，如下所示：
<item
    android:id="@+id/rootFragment"
    android:title="To Root" />
<item
    android:id="@+id/firstFragment"
    android:title="To First" />
<item
    android:id="@+id/settingsFragment"
    android:title="To Settings" />

并添加

 setupWithNavController(nav_view, navController )

在您的主活动中，不要使用

，而是
nav_drawer.setNavigationItemSelectedListener {
        val navController = findNavController( R.id.nav_host_fragment )

        when (it.itemId) {
            R.id.nav_drawer_root_menu_item     -> navController.navigate(R.id.rootFragment)
            R.id.nav_drawer_first_menu_item    -> navController.navigate(R.id.action_rootFragment_to_firstFragment)
            R.id.nav_drawer_settings_menu_item -> navController.navigate(R.id.action_rootFragment_to_settingsFragment)
        }

        main_activity_drawer_layout.closeDrawer(GravityCompat.START)

        true
    }
1
这意味着navController有一个当前状态，在调用navController.navigate(R.id.action_to_something)时，navController必须已经位于动作起源的起始节点。很有道理。这也可能解释了我的第二个错误，即我还没有将navController的当前状态设置为根节点。不过我不知道如何将当前状态设置为根节点。我以为主页节点会自动分配，但对于我的其他代码库来说并没有起作用。 - Jim Leask
setupWithNavController是什么？ - IgorGanapolsky
0

2) 如果崩溃发生在屏幕旋转时，请在活动中使用以下方法升级导航版本模块至2.2.0或更高版本

implementation "androidx.navigation:navigation-fragment-ktx:2.2.0"
implementation "androidx.navigation:navigation-ui-ktx:2.2.0"
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