本文介绍了在Android导航组件中处理onBackPressed的处理方法,对大家解决问题具有一定的参考价值,需要的朋友们下面随着小编来一起学习吧!

问题描述

我已经在Android中实现了带有导航组件的导航抽屉.单击后退时,我有5个片段想回到我的 HomeFragment .目前,它们停留在BackStack上,而不是转到我想要的片段,而是转到第一个片段.这是我的 nav_graph :

I have implemented navigation Drawer with Navigation Components in Android. I have 5 fragments that I want to go back to my HomeFragment when I click on back pressed. For the moment they stay onBackStack and do not go to my desired fragment but go to whatever fragment was first.This is my nav_graph :

<?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"
            app:startDestination="@id/setupFragment"
            android:id="@+id/treasure_nav"
            android:label="Pick a country">
    <fragment android:id="@+id/homeFragment"
              android:name="com.stavro_xhardha.pockettreasure.ui.home.HomeFragment"
              android:label="Home"
              tools:layout="@layout/fragment_home">
        <action android:id="@+id/action_home_fragment_to_namesFragment2"
                app:popUpTo="@id/homeFragment"
                app:destination="@id/namesFragment"/>
        <action android:id="@+id/action_home_fragment_to_quranFragment"
                app:popUpTo="@id/homeFragment"
                app:destination="@id/quranFragment"/>
        <action android:id="@+id/action_homeFragment_to_tasbeehFragment"
                app:popUpTo="@id/homeFragment"
                app:destination="@id/tasbeehFragment"/>
        <action android:id="@+id/action_homeFragment_to_galleryFragment"
                app:popUpTo="@id/homeFragment"
                app:destination="@id/galleryFragment"/>
        <action android:id="@+id/action_homeFragment_to_newsFragment"
                app:popUpTo="@id/homeFragment"
                app:destination="@id/newsFragment"/>
        <action android:id="@+id/action_homeFragment_to_settingsFragment"
                app:popUpTo="@id/homeFragment"
                app:destination="@id/settingsFragment"/>
    </fragment>
    <fragment
            android:id="@+id/namesFragment"
            android:name="com.stavro_xhardha.pockettreasure.ui.names.NamesFragment"
            android:label="Names of Allah"
            tools:layout="@layout/fragment_names"/>
    <fragment
            android:id="@+id/quranFragment"
            android:name="com.stavro_xhardha.pockettreasure.ui.quran.QuranFragment"
            android:label="Quran"
            tools:layout="@layout/fragment_quran"/>
    <fragment android:id="@+id/tasbeehFragment"
              android:name="com.stavro_xhardha.pockettreasure.ui.tasbeeh.TasbeehFragment"
              android:label="Tasbeeh"
              tools:layout="@layout/fragment_tasbeeh"/>
    <fragment android:id="@+id/galleryFragment"
              android:name="com.stavro_xhardha.pockettreasure.ui.gallery.GalleryFragment"
              android:label="Gallery"
              tools:layout="@layout/fragment_gallery"/>
    <fragment android:id="@+id/newsFragment"
              android:name="com.stavro_xhardha.pockettreasure.ui.news.NewsFragment"
              android:label="News"
              tools:layout="@layout/fragment_news"/>
    <fragment android:id="@+id/settingsFragment"
              android:name="com.stavro_xhardha.pockettreasure.ui.settings.SettingsFragment"
              android:label="Settings"
              tools:layout="@layout/fragment_settings"/>
    <fragment android:id="@+id/setupFragment"
              android:name="com.stavro_xhardha.pockettreasure.ui.setup.SetupFragment"
              android:label="Pick country"
              tools:layout="@layout/fragment_setup">
        <action android:id="@+id/action_setupFragment_to_homeFragment3"
                app:destination="@+id/homeFragment"
                app:launchSingleTop="true"
                app:popUpTo="@+id/treasure_nav"
                app:popUpToInclusive="true"/>
    </fragment>
</navigation>

这是我的MainActivity(也是唯一的)中的 onBackPressed :

And this is my onBackPressed in my MainActivity (and the only one) :

override fun onBackPressed() {
        if (drawer_layout.isDrawerOpen(GravityCompat.START)) {
            drawer_layout.closeDrawer(GravityCompat.START)
        } else {
                super.onBackPressed()
        }
    }

编辑:当我删除 super.onBackPressed()并将其替换为: findNavController(R.id.nav_host_fragment).popBackStack(R.id.homeFragment,false)我实现了我想要的.唯一的问题是,当我进入 homeFragment 时,我想结束该应用程序,但不能结束.

Edit: When i remove the super.onBackPressed() and replace it with : findNavController(R.id.nav_host_fragment).popBackStack(R.id.homeFragment, false) I achieve what I want. The only problem is that when I am in the homeFragment I want to end the app but I can't.

推荐答案

如果我的理解是正确的,那么无论您在导航流程中的哪个位置,都想返回HomeFragment.对于这种情况,您可以尝试通过addOnBackPressedCallback在Fragments上注册OnBackPressedCallback,然后调用popBackStack导航到HomeFragment.尝试将其添加到需要在backpress上返回HomeFragment的Fragments的onViewCreated中:

If my understanding is correct, you want to go back to HomeFragment wherever you are in the navigation flow. For this case you could try registering OnBackPressedCallback on your Fragments via addOnBackPressedCallback, and call popBackStack to navigate to your HomeFragment. Try adding this to Fragments' onViewCreated that need to go back to HomeFragment on backpress:

@Override
    public void onViewCreated(@NonNull View view, @Nullable Bundle savedInstanceState) {
        super.onViewCreated(view, savedInstanceState);
        navController = Navigation.findNavController(view);

        requireActivity().addOnBackPressedCallback(getViewLifecycleOwner(), () -> {
               navController.popBackStack(R.id.homeFragment, false);
            });
            return true;
        });

这篇关于在Android导航组件中处理onBackPressed的文章就介绍到这了,希望我们推荐的答案对大家有所帮助,也希望大家多多支持!

06-07 05:16