android - 如何在点击 FAB 时启动新的导航图？

Question

问题:

我是 Android 新手，我认为我在概念上遇到了一些非常错误的问题。
我不能在同一个 Activity 中有两个 navHostFragments。我得到这个错误。

Error inflating class fragment

bottomNavigationView 图形本身工作得很好，我可以毫无问题地切换选项卡，当尝试在 FAB 点击时添加新导航时出现问题。 我不想用新的 fragment 容器替换 fragment 容器，我想启动一个全屏的新 fragment

语境:

在主要 Activity 中，我有一个 可折叠工具栏、bottomNavigationView 和 FAB 按钮 .我还想要两个 NavHostFragment，每个导航图一个。

第一个导航图处理bottomNavigationView选项卡之间的切换( fragment 的内容显示在可折叠工具栏下方和bottomNavigationView顶部)

第二个导航图将出现在 FAB 点击，并将全屏

我有的:

这就是 activity_main.xml 的样子

        <com.google.android.material.appbar.AppBarLayout
            .....
        />
        <fragment
            android:id="@+id/waiterNavigationHostFragment"
            android:name="androidx.navigation.fragment.NavHostFragment"
            android:layout_width="match_parent"
            android:layout_height="match_parent"
            app:defaultNavHost="false"
            app:navGraph="@navigation/waiter_navigation" />

        <FrameLayout
            android:layout_width="match_parent"
            android:layout_height="match_parent"
            android:layout_below="@+id/appBarLayout"
            app:layout_behavior="@string/appbar_scrolling_view_behavior">  

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

        </FrameLayout>
        <FrameLayout>
            <com.google.android.material.floatingactionbutton.FloatingActionButton
                .........
            />
            <com.google.android.material.bottomnavigation.BottomNavigationView
                ........
            />
        </FrameLayout>

这是 waiter_navigation.xml 应该在 FAB 点击时全屏显示:

<?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/waiter_screen">
    <fragment
        android:id="@+id/waiter_screen"
        android:name=".app.ui.waiter.WaiterScreenFragment"
        android:label="fragment_waiter"
        tools:layout="@layout/fragment_waiter" >
        <action
            android:id="@+id/navigate_to_menu_screen"
            app:destination="@id/menuScreenFragment" />
    </fragment>
    <fragment
        android:id="@+id/menu_screen"
        android:name=".app.ui.menu.MenuScreenFragment"
        android:label="MenuScreenFragment"
        tools:layout="@layout/fragment_menu" />
</navigation>

这是位于可折叠应用栏和bottomNavigationView之间的bottom_navigation.xml:

<?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/bottom_navigation"
    app:startDestination="@id/home_screen">
    <fragment
        android:id="@+id/home_screen"
        android:name=".app.ui.home.HomeScreenFragment"
        android:label="fragment_home"
        tools:layout="@layout/fragment_home" >
        <action
            android:id="@+id/navigate_to_receipt_screen"
            app:destination="@id/receipt_screen"
            app:enterAnim="@anim/slide_in_right"
            app:exitAnim="@anim/slide_out_left"/>
    </fragment>
    <fragment
        android:id="@+id/receipt_screen"
        android:name=".app.ui.receipt.ReceiptScreenFragment"
        android:label="fragment_explore"
        tools:layout="@layout/fragment_receipt" >
        <action
            android:id="@+id/navigate_to_profile_screen"
            app:destination="@id/profile_screen"
            app:enterAnim="@anim/slide_in_right"
            app:exitAnim="@anim/slide_out_left"/>
    </fragment>
    <fragment
        android:id="@+id/profile_screen"
        android:name=".app.ui.profile.ProfileScreenFragment"
        android:label="fragment_more"
        tools:layout="@layout/fragment_profile" />

</navigation>

完整的错误详细信息

2020-02-24 11:54:30.401 16857-16857/com.restaurant.app E/AndroidRuntime: FATAL EXCEPTION: main Process: com.restaurant.app, PID: 16857 java.lang.RuntimeException: Unable to start activity ComponentInfo{com.restaurant.app/com.restaurant.app.ui.main.MainScreenActivity}: android.view.InflateException: Binary XML file line #45: Binary XML file line #45: Error inflating class fragment at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2946) at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:3081) at android.app.servertransaction.LaunchActivityItem.execute(LaunchActivityItem.java:78) at android.app.servertransaction.TransactionExecutor.executeCallbacks(TransactionExecutor.java:108) at android.app.servertransaction.TransactionExecutor.execute(TransactionExecutor.java:68) at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1831) at android.os.Handler.dispatchMessage(Handler.java:106) at android.os.Looper.loop(Looper.java:201) at android.app.ActivityThread.main(ActivityThread.java:6806) at java.lang.reflect.Method.invoke(Native Method) at com.android.internal.os.RuntimeInit$MethodAndArgsCaller.run(RuntimeInit.java:547) at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:873) Caused by: android.view.InflateException: Binary XML file line #45: Binary XML file line #45: Error inflating class fragment Caused by: android.view.InflateException: Binary XML file line #45: Error inflating class fragment Caused by: java.lang.IllegalStateException: no start destination defined via app:startDestination for com.flypay.restaurant.app:id/waiter_screen at androidx.navigation.NavGraphNavigator.navigate(NavGraphNavigator.java:61) at androidx.navigation.NavGraphNavigator.navigate(NavGraphNavigator.java:28) at androidx.navigation.NavController.navigate(NavController.java:933) at androidx.navigation.NavController.onGraphCreated(NavController.java:577) at androidx.navigation.NavController.setGraph(NavController.java:534) at androidx.navigation.NavController.setGraph(NavController.java:499) at androidx.navigation.NavController.setGraph(NavController.java:481) at androidx.navigation.fragment.NavHostFragment.onCreate(NavHostFragment.java:237) at androidx.fragment.app.Fragment.performCreate(Fragment.java:2684) at androidx.fragment.app.FragmentStateManager.create(FragmentStateManager.java:280) at androidx.fragment.app.FragmentManager.moveToState(FragmentManager.java:1175) at androidx.fragment.app.FragmentManager.moveToState(FragmentManager.java:1356) at androidx.fragment.app.FragmentLayoutInflaterFactory.onCreateView(FragmentLayoutInflaterFactory.java:109) at androidx.fragment.app.FragmentController.onCreateView(FragmentController.java:135) at androidx.fragment.app.FragmentActivity.dispatchFragmentsOnCreateView(FragmentActivity.java:356) at androidx.fragment.app.FragmentActivity.onCreateView(FragmentActivity.java:335) at android.view.LayoutInflater.createViewFromTag(LayoutInflater.java:784) at android.view.LayoutInflater.createViewFromTag(LayoutInflater.java:734) at android.view.LayoutInflater.rInflate(LayoutInflater.java:867) at android.view.LayoutInflater.rInflateChildren(LayoutInflater.java:828) at android.view.LayoutInflater.inflate(LayoutInflater.java:519) at android.view.LayoutInflater.inflate(LayoutInflater.java:427) at android.view.LayoutInflater.inflate(LayoutInflater.java:374) at androidx.appcompat.app.AppCompatDelegateImpl.setContentView(AppCompatDelegateImpl.java:469) at androidx.appcompat.app.AppCompatActivity.setContentView(AppCompatActivity.java:140) at com.flypay.restaurant.app.ui.main.MainScreenActivity.onCreate(MainScreenActivity.kt:17) at android.app.Activity.performCreate(Activity.java:7224) at android.app.Activity.performCreate(Activity.java:7213) at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1272) at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2926) at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:3081) 2020-02-24 11:54:30.402 16857-16857/com.restaurant.app E/AndroidRuntime: at android.app.servertransaction.LaunchActivityItem.execute(LaunchActivityItem.java:78) at android.app.servertransaction.TransactionExecutor.executeCallbacks(TransactionExecutor.java:108) at android.app.servertransaction.TransactionExecutor.execute(TransactionExecutor.java:68) at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1831) at android.os.Handler.dispatchMessage(Handler.java:106) at android.os.Looper.loop(Looper.java:201) at android.app.ActivityThread.main(ActivityThread.java:6806) at java.lang.reflect.Method.invoke(Native Method) at com.android.internal.os.RuntimeInit$MethodAndArgsCaller.run(RuntimeInit.java:547) at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:873)

Answer 1

<?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"
    app:startDestination="@id/ADD_SCREEN_NAME"
    xmlns:tools="http://schemas.android.com/tools"
    android:id="@+id/waiter_screen">
    <fragment
        android:id="@+id/waiter_screen"
        android:name=".app.ui.waiter.WaiterScreenFragment"
        android:label="fragment_waiter"
        tools:layout="@layout/fragment_waiter" >
        <action
            android:id="@+id/navigate_to_menu_screen"
            app:destination="@id/menuScreenFragment" />
    </fragment>
    <fragment
        android:id="@+id/menu_screen"
        android:name=".app.ui.menu.MenuScreenFragment"
        android:label="MenuScreenFragment"
        tools:layout="@layout/fragment_menu" />
</navigation>