Question

在我的应用程序中，我使用了一个活动和四个片段。在这个应用程序中，我使用了导航组件。我的片段加载顺序是A-> B-> C-> D

在片段D中，在设备后退按钮上按下，我想从后堆栈中移除片段C，以便可以打开片段B。有人建议我该怎么办预先谢谢你

这是我的navigation_graph.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/navigation_graph"

    app:startDestination="@id/firstFragment"
    >
    <fragment
        android:id="@+id/firstFragment"
        android:name="com.education.javaprogramming.fragments.MainFragment"
        android:label="fragment_first"
        tools:layout="@layout/activity_main" >

        <action
            android:id="@+id/action_firstFragment_to_displayList1Fragment"
            app:destination="@id/displayList1Fragment"
            app:enterAnim="@anim/enter"
            app:exitAnim="@anim/exit"
            app:popEnterAnim="@anim/pop_enter"
            app:popExitAnim="@anim/pop_exit"
            />
        <action
            android:id="@+id/action_firstFragment_to_displayList2Fragment"
            app:destination="@id/displayList2Fragment"
            app:enterAnim="@anim/enter"
            app:exitAnim="@anim/exit"
            app:popEnterAnim="@anim/pop_enter"
            app:popExitAnim="@anim/pop_exit"

            />
        <action
            android:id="@+id/action_firstFragment_to_helpFragment"
            app:destination="@id/helpFragment"
            app:enterAnim="@anim/enter"
            app:exitAnim="@anim/exit"
            app:popEnterAnim="@anim/pop_enter"
            app:popExitAnim="@anim/pop_exit"
            />
        <action
            android:id="@+id/action_firstFragment_to_quizzFragment"
            app:destination="@id/quizzFragment"
            app:enterAnim="@anim/enter"
            app:exitAnim="@anim/exit"
            app:popEnterAnim="@anim/pop_enter"
            app:popExitAnim="@anim/pop_exit"

            />
    </fragment>
    <fragment
        android:id="@+id/displayList1Fragment"
        android:name="com.education.javaprogramming.fragments.DisplayList1Fragment"
        android:label="fragment_display_list1"
        tools:layout="@layout/fragment_display_list1"

        >
        <argument
            android:name="position1"
            app:argType="integer" />
        <action
            android:id="@+id/action_displayList1Fragment_to_firstFragment"
            app:destination="@id/firstFragment" />
        <argument
            android:name="name"
            app:argType="string" />
        <action
            android:id="@+id/action_displayList1Fragment_to_displayList2Fragment"
            app:destination="@id/displayList2Fragment"
            app:enterAnim="@anim/enter"
            app:exitAnim="@anim/exit"
            app:popEnterAnim="@anim/pop_enter"
            app:popExitAnim="@anim/pop_exit"


            />
    </fragment>
    <fragment
        android:id="@+id/displayList2Fragment"
        android:name="com.education.javaprogramming.fragments.DisplayList2Fragment"
        android:label="fragment_display_list2"
        tools:layout="@layout/fragment_display_list2" >
        <action
            android:id="@+id/action_displayList2Fragment_to_displayList1Fragment"
            app:destination="@id/displayList1Fragment"

            app:enterAnim="@anim/enter"
            app:exitAnim="@anim/exit"
            app:popEnterAnim="@anim/pop_enter"
            app:popExitAnim="@anim/pop_exit"
            />
        <action
            android:id="@+id/action_displayList2Fragment_to_firstFragment"
            app:destination="@id/firstFragment"
            app:enterAnim="@anim/enter"
            app:exitAnim="@anim/exit"
            app:popEnterAnim="@anim/pop_enter"
            app:popExitAnim="@anim/pop_exit"

            />
        <argument
            android:name="position1"
            app:argType="integer" />
        <argument
            android:name="position2"
            app:argType="integer" />
        <argument
            android:name="name"
            app:argType="string" />
        <action
            android:id="@+id/action_displayList2Fragment_to_displayListInDeFragment"
            app:destination="@id/displayListInDeFragment"
            app:enterAnim="@anim/enter"
            app:exitAnim="@anim/exit"
            app:popEnterAnim="@anim/pop_enter"
            app:popExitAnim="@anim/pop_exit"

            />
    </fragment>
    <fragment
        android:id="@+id/displayListInDeFragment"
        android:name="com.education.javaprogramming.fragments.DisplayListInDeFragment"
        android:label="fragment_display_list_in_de"
        tools:layout="@layout/fragment_display_list_in_de" >
        <action
            android:id="@+id/action_displayListInDeFragment_to_displayList2Fragment"
            app:destination="@id/displayList2Fragment"
            app:enterAnim="@anim/enter"
            app:exitAnim="@anim/exit"
            app:popEnterAnim="@anim/pop_enter"
            app:popExitAnim="@anim/pop_exit"

            />
        <argument
            android:name="position1"
            app:argType="integer" />
        <argument
            android:name="position2"
            app:argType="integer" />
        <argument
            android:name="position3"
            app:argType="integer" />
        <argument
            android:name="name"
            app:argType="string" />
    </fragment>
    <fragment
        android:id="@+id/helpFragment"
        android:name="com.education.javaprogramming.fragments.HelpFragment"
        android:label="fragment_help"
        tools:layout="@layout/fragment_help" >
        <action
            android:id="@+id/action_helpFragment_to_firstFragment"
            app:destination="@id/firstFragment"
            app:enterAnim="@anim/enter"
            app:exitAnim="@anim/exit"
            app:popEnterAnim="@anim/pop_enter"
            app:popExitAnim="@anim/pop_exit"
            />
        <argument
            android:name="position1"
            app:argType="integer" />
        <argument
            android:name="name"
            app:argType="string" />
        <action
            android:id="@+id/action_helpFragment_to_aboutFragment"
            app:destination="@id/aboutFragment"
            app:enterAnim="@anim/enter"
            app:exitAnim="@anim/exit"
            app:popEnterAnim="@anim/pop_enter"
            app:popExitAnim="@anim/pop_exit"

            />
    </fragment>
    <fragment
        android:id="@+id/aboutFragment"
        android:name="com.education.javaprogramming.fragments.AboutFragment"
        android:label="fragment_about"
        tools:layout="@layout/fragment_about" >
        <action
            android:id="@+id/action_aboutFragment_to_helpFragment"
            app:destination="@id/helpFragment"
            app:enterAnim="@anim/enter"
            app:exitAnim="@anim/exit"
            app:popEnterAnim="@anim/pop_enter"
            app:popExitAnim="@anim/pop_exit"
            />
    </fragment>
    <fragment
        android:id="@+id/quizzFragment"
        android:name="com.education.javaprogramming.fragments.QuizzFragment"
        android:label="fragment_quizz"
        tools:layout="@layout/fragment_quizz" >
        <action
            android:id="@+id/action_quizzFragment_to_firstFragment"
            app:destination="@id/firstFragment"
            app:enterAnim="@anim/enter"
            app:exitAnim="@anim/exit"
            app:popEnterAnim="@anim/pop_enter"
            app:popExitAnim="@anim/pop_exit"

            />
        <action
            android:id="@+id/action_quizzFragment_to_displayExamFragment"
            app:destination="@id/displayExamFragment" />
    </fragment>
    <fragment
        android:id="@+id/displayExamFragment"
        android:name="com.education.javaprogramming.fragments.DisplayExamFragment"
        android:label="fragment_display_exam"
        tools:layout="@layout/fragment_display_exam" >
        <action
            android:id="@+id/action_displayExamFragment_to_quizzFragment"
            app:destination="@id/quizzFragment"
            app:enterAnim="@anim/enter"
            app:exitAnim="@anim/exit"
            app:popEnterAnim="@anim/pop_enter"
            app:popExitAnim="@anim/pop_exit"

            />
        <argument
            android:name="position1"
            app:argType="integer" />
        <action
            android:id="@+id/action_displayExamFragment_to_resultFragment"
            app:destination="@id/resultFragment" />
    </fragment>
    <fragment
        android:id="@+id/resultFragment"
        android:name="com.education.javaprogramming.fragments.ResultFragment"
        android:label="fragment_result"
        tools:layout="@layout/fragment_result" >
        <action

            android:id="@+id/action_resultFragment_to_quizzFragment"
            app:destination="@id/quizzFragment" />
        <argument android:name="givenAnswers"
            app:argType="reference"
            />
        <argument android:name="actualAnswers"
            app:argType="reference"
            />
    </fragment>


</navigation>

Answer 1

您应该使用

      app:popUpTo="@id/id_of_c_fragment" 
      app:popUpToInclusive="true"
      app:popUpTo="@id/id_of_d_fragment"
      app:popUpToInclusive="true"

在操作范围内的导航图中。

Answer 2

您可以使用navController.popBackStack(int destinationId,bool inclusive)方法，（请注意boolean的值）

尝试将控制器的后退栈弹回到特定的目的地。例如。

navController.popBackStack(R.id.dest_id_of_B, true)

Answer 3

在片段D中，如果要返回片段B（删除片段C），则可以使用：

Navigation.findNavController(requireView()).popBackStack(
    R.id.id_of_fragment_C, true)

id_of_fragment_C是您要跳过的片段的ID。

如何从片段导航组件的后堆栈中仅删除一个片段？

3 个答案: