Android Jetpack Navigation、BottomNavigationView 与 Youtube 或 Instagram 类似正确的返回导航(片段返回堆栈)? [英] Android Jetpack Navigation, BottomNavigationView with Youtube or Instagram like proper back navigation (fragment back stack)?

问题描述

Android Jetpack Navigation、BottomNavigationView 在返回按钮点击时具有自动片段返回堆栈?

Android Jetpack Navigation, BottomNavigationView with auto fragment back stack on back button click?

我想要的是，在用户一个接一个地选择多个标签后，用户点击后退按钮应用程序必须重定向到他/她打开的最后一页.

What I wanted, after choosing multiple tabs one after another by user and user click on back button app must redirect to the last page he/she opened.

我使用 Android ViewPager 实现了相同的效果，方法是将当前选定的项目保存在 ArrayList 中.Android Jetpack Navigation 发布后是否有任何自动返回堆栈?我想使用导航图来实现它

I achieved the same using Android ViewPager, by saving the currently selected item in an ArrayList. Is there any auto back stack after Android Jetpack Navigation Release? I want to achieve it using navigation graph

activity_main.xml

<?xml version="1.0" encoding="utf-8"?>
<android.support.constraint.ConstraintLayout 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/container"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    tools:context=".main.MainActivity">

    <fragment
        android:id="@+id/my_nav_host_fragment"
        android:name="androidx.navigation.fragment.NavHostFragment"
        android:layout_width="match_parent"
        android:layout_height="0dp"
        app:defaultNavHost="true"
        app:layout_constraintBottom_toTopOf="@+id/navigation"
        app:layout_constraintEnd_toEndOf="parent"
        app:layout_constraintStart_toStartOf="parent"
        app:layout_constraintTop_toTopOf="parent"
        app:navGraph="@navigation/nav_graph" />

    <android.support.design.widget.BottomNavigationView
        android:id="@+id/navigation"
        android:layout_width="0dp"
        android:layout_height="wrap_content"
        android:layout_marginStart="0dp"
        android:layout_marginEnd="0dp"
        android:background="?android:attr/windowBackground"
        app:layout_constraintBottom_toBottomOf="parent"
        app:layout_constraintLeft_toLeftOf="parent"
        app:layout_constraintRight_toRightOf="parent"
        app:menu="@menu/navigation" />

</android.support.constraint.ConstraintLayout>

navigation.xml

<?xml version="1.0" encoding="utf-8"?>
<menu xmlns:android="http://schemas.android.com/apk/res/android">

    <item
        android:id="@+id/navigation_home"
        android:icon="@drawable/ic_home"
        android:title="@string/title_home" />

    <item
        android:id="@+id/navigation_people"
        android:icon="@drawable/ic_group"
        android:title="@string/title_people" />

    <item
        android:id="@+id/navigation_organization"
        android:icon="@drawable/ic_organization"
        android:title="@string/title_organization" />

    <item
        android:id="@+id/navigation_business"
        android:icon="@drawable/ic_business"
        android:title="@string/title_business" />

    <item
        android:id="@+id/navigation_tasks"
        android:icon="@drawable/ic_dashboard"
        android:title="@string/title_tasks" />

</menu>

还添加了

bottomNavigation.setupWithNavController(Navigation.findNavController(this, R.id.my_nav_host_fragment))

我从 Levi Moreira 那里得到了一个答案，如下

I got one answer from Levi Moreira, as follows

navigation.setOnNavigationItemSelectedListener {item ->

            onNavDestinationSelected(item, Navigation.findNavController(this, R.id.my_nav_host_fragment))

        }

但是这样做只会发生最后一次打开的片段的实例再次创建.

But by doing this only happening is that last opened fragment's instance creating again.

为 BottomNavigationView 提供适当的后退导航

Providing proper Back Navigation for BottomNavigationView

推荐答案

随着2.4.0版本的导航包，终于正式支持了！

With the version 2.4.0 of the navigation package, it is finally officially supported!

https://developer.android.com/jetpack/androidx/releases/navigation#version_240_2

不仅如此:将导航库上传到此版本后，此功能是默认行为.作为旁注，现在这个默认行为包括在它们之间导航时不会重新创建片段，这似乎是非常需要的东西.

Not only that: after uploading the navigation library to this version, this feature is the default behaviour. And as a side note, now this default behaviour includes that fragments are not recreated when navigating among them, that seemed to be something quite requested.

这篇关于Android Jetpack Navigation、BottomNavigationView 与 Youtube 或 Instagram 类似正确的返回导航(片段返回堆栈)?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IT屋！