IssueTracker

Project: platform/frameworks/support
Branch: androidx-main

commit 96cee05bdb8f61a92e4be00a52b991cfc1ed2f4e
Author: Clara Fok <clarafok@google.com>
Date:   Wed Mar 01 12:28:09 2023

    Add FragmentNavigator test to assert entry destroyed
   
    Add test to assert that NavBackStackEntry is destroyed after being restored upon recreation/configuration change.
   
    Asserts that the fix on this bug also fixes b/270610768.
   
    Test: ./gradlew navigation:navigation-fragment
    Bug: 270447657
    Change-Id: I8874d2dfaa17e560dd2f6d9da54e435494c187d2

M       navigation/navigation-fragment/src/androidTest/java/androidx/navigation/fragment/FragmentNavigatorTest.kt

https://android-review.googlesource.com/2464422

popUpTo will be able to do that: https://stackoverflow.com/questions/50336112/how-to-disable-up-in-navigation-for-some-fragment-with-the-new-navigation-archit

At current now，there is two ways to do the above。

One：
In the NavHostFragment's Activity, override the onBackPress() method,adn if the current NavDestination is MainFragment then just finish the Activity.

@Override
    public void onBackPressed() {
       NavDestination navDestination = mNavController.getCurrentDestination();
        if (navDestination != null
                && navDestination.getId() == R.id.mainFragment) {
            finish();
            return;
        }
        super.onBackPressed();
    }

Two:
Set the to MainFragment action in Navigation_graph app:popUpTo="@id/nav_graph" and app:popUpToInclusive="true"

<?xml version="1.0" encoding="utf-8"?>
<navigation
    android:id="@+id/nav_graph"
    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/splashFragment">

    <fragment
        android:id="@+id/splashFragment"
        android:name="com.ihuman.storydemo.fragment.splash.SplashFragment"
        android:label="fragment_splash"
        tools:layout="@layout/fragment_splash">
        <action
            android:id="@+id/action_splashFragment_to_mainFragment"
            app:destination="@id/mainFragment"
            app:enterAnim="@anim/anim_right_in"
            app:exitAnim="@anim/anim_left_out"
            app:popEnterAnim="@anim/anim_left_in"
            app:popExitAnim="@anim/anim_right_out"
            app:popUpTo="@id/nav_graph"
            app:popUpToInclusive="true"/>
        <action
            android:id="@+id/action_splashFragment_to_guideFragment"
            app:destination="@id/guideFragment"
            app:enterAnim="@anim/anim_right_in"
            app:exitAnim="@anim/anim_left_out"
            app:popEnterAnim="@anim/anim_left_in"
            app:popExitAnim="@anim/anim_right_out"
            app:popUpTo="@id/nav_graph"
            app:popUpToInclusive="true"/>
    </fragment>
       
        <fragment
        android:id="@+id/guideFragment"
        android:name="com.ihuman.storydemo.fragment.guide.GuideFragment"
        android:label="GuideFragment"
        tools:layout="@layout/fragment_guide">
        <action
            android:id="@+id/action_guideFragment_to_mainFragment"
            app:destination="@id/mainFragment"
            app:enterAnim="@anim/anim_right_in"
            app:exitAnim="@anim/anim_left_out"
            app:popEnterAnim="@anim/anim_left_in"
            app:popExitAnim="@anim/anim_right_out"
            app:popUpTo="@id/nav_graph"
            app:popUpToInclusive="true"/>
    </fragment>

    <fragment
        android:id="@+id/mainFragment"
        android:name="com.ihuman.storydemo.fragment.main.MainFragment"
        android:label="fragment_main"
        tools:layout="@layout/fragment_main">
       
    </fragment>
       
</navigation>

Wish for help!