Question

我有一个活动Dashboard Activity，其中有一个片段和一个底部导航菜单，该菜单在DashboardActivity.kt中设置如下：

setContentView(R.layout.activity_dashboard)
val navView: BottomNavigationView = findViewById(R.id.nav_view)
val navController = findNavController(R.id.nav_host_fragment)
navView.setupWithNavController(navController)

底部的导航栏包含3个项目：@+id/navigation_scoreboard，@+id/navigation_dashboard和@+id/navigation_gamesettings

在我的@+id/navigation_dashboard底部导航菜单项内-用户可以在输入字段中输入一些数据，然后按一下我进行API调用的按钮，然后导航到结果屏幕@+id/slipup_result_fragment使用导航+实时数据观察器的API调用成功。

现在的问题是：：当我离开结果屏幕@+id/slipup_result_fragment时，例如说要转到底部导航菜单中的另一个项目，然后按{ {1}}，我再次进入结果屏幕，而不是原始片段-@+id/navigation_dashboard，似乎无法找到返回原始片段的方法。

我在做什么错了？

更新：@+id/navigation_dashboard中片段的导航图如下：

Dashboard Activity

Update＃2：底部菜单XML如下：

<?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/mobile_navigation"
    app:startDestination="@+id/navigation_scoreboard">

    <fragment
        android:id="@+id/navigation_scoreboard"
        android:name="com.ezchange.mvp.ui.scoreboard.ScoreboardFragment"
        android:label="@string/title_scoreboard"
        tools:layout="@layout/fragment_scoreboard" />

    <fragment
        android:id="@+id/navigation_dashboard"
        android:name="com.ezchange.mvp.ui.slipup.SlipUpFragment"
        android:label="@string/title_slipup"
        tools:layout="@layout/fragment_slipup" >
        <action
            android:id="@+id/action_navigation_dashboard_to_slipUpResultFragment"
            app:destination="@id/slipup_result_fragment"
            app:popUpTo="@id/navigation_dashboard"
            app:popUpToInclusive="true" />
    </fragment>

    <fragment
        android:id="@+id/navigation_gamesettings"
        android:name="com.ezchange.mvp.ui.gamesettings.GameSettingsFragment"
        android:label="@string/title_game_settings"
        tools:layout="@layout/fragment_game_settings" />

    <fragment
        android:id="@+id/slipup_result_fragment"
        android:name="com.ezchange.mvp.ui.slipup.SlipUpResultFragment"
        android:label="fragment_slip_up_result"
        tools:layout="@layout/fragment_slip_up_result" >
        <action
            android:id="@+id/action_slipUpResultFragment_to_navigation_scoreboard"
            app:destination="@id/navigation_scoreboard" />
    </fragment>

</navigation>

Answer 1

使用action_navigation_dashboard_to_slipUpResultFragment导航控制器导航时，请遵循以下信息-

SlipUpFragment-> SlipUpResultFragment

在导航后，它将带您到SlipUpFragment，没有任何问题。

导航到navigation_gamesettings后，导航应该具有以下信息-

SlipUpFragment-> SlipUpResultFragment-> GameSettingsFragment

但是没有这样的action_slipUpResultFragment_to_navigation_gamesettings，这就是为什么导航导航器时会丢失的原因。

因此SlipUpResultFragment必须采取以下措施-

<fragment
    android:id="@+id/slipup_result_fragment"
    android:label="fragment_slip_up_result"
    android:name="com.ezchange.mvp.ui.slipup.SlipUpResultFragment"
    tools:layout="@layout/fragment_slip_up_result">

    <action
        android:id="@+id/action_slipUpResultFragment_to_navigation_gamesettings"
        app:destination="@id/navigation_gamesettings"
        app:popUpTo="@+id/navigation_dashboard"
        app:popUpToInclusive="true" />
    <action
        android:id="@+id/action_slipUpResultFragment_to_navigation_scoreboard"
        app:destination="@id/navigation_scoreboard"
        app:popUpTo="@+id/navigation_dashboard"
        app:popUpToInclusive="true" />
</fragment>

添加app:popUpToInclusive="true"和app:popUpTo="@+id/navigation_dashboard"以确保在导航后，您将转到 SlipUpFragment ，而不再是 SlipUpResultFragment 。

编辑1

使用以下NavGraph可以达到预期的效果-PSR of result

<?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/mobile_navigation"
    app:startDestination="@+id/navigation_home">

    <fragment
        android:id="@+id/navigation_home"
        android:name="com.example.bottomnavigationtest.ui.home.HomeFragment"
        android:label="@string/title_home"
        tools:layout="@layout/fragment_home" />

    <fragment
        android:id="@+id/navigation_dashboard"
        android:name="com.example.bottomnavigationtest.ui.dashboard.DashboardFragment"
        android:label="@string/title_dashboard"
        tools:layout="@layout/fragment_dashboard" >
        <action
            android:id="@+id/action_navigation_dashboard_to_detailsFagment"
            app:destination="@id/detailsFagment" />

    </fragment>

    <fragment
        android:id="@+id/navigation_notifications"
        android:name="com.example.bottomnavigationtest.ui.notifications.NotificationsFragment"
        android:label="@string/title_notifications"
        tools:layout="@layout/fragment_notifications" >
    </fragment>

    <fragment
        android:id="@+id/detailsFagment"
        android:name="com.example.bottomnavigationtest.ui.dashboard.details.DetailsFagment"
        android:label="fragment_details_fagment"
        tools:layout="@layout/fragment_details_fagment" >
        <action
            android:id="@+id/action_detailsFagment_to_navigation_home"
            app:destination="@id/navigation_home" />
    </fragment>

</navigation>

快乐编码！

片段和Jetpack导航的底部导航行为

1 个答案: