如何根据该值以编程方式添加startDestination？

Question

如何根据值以编程方式添加起始目标？例如，如果整数变量为0，则我希望启动导航\u main\u countries\u fragment，否则启动导航\u main\u categories\u fragment。

内部activity\u main

<androidx.fragment.app.FragmentContainerView
    android:id="@+id/activity_main_container"
    android:name="androidx.navigation.fragment.NavHostFragment"
    android:layout_width="match_parent"
    android:layout_height="0dp"
    app:navGraph="@navigation/navigation_main" //I deleted this line already
    android:layout_weight="1" />

内部导航主

<?xml version="1.0" encoding="utf-8"?>
<navigation xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools"
    app:startDestination="@id/navigation_main_countries_fragment" //I deleted this line already
    tools:ignore="InvalidNavigation">

    <fragment
        android:id="@+id/navigation_main_countries_fragment"
        android:name="com.test.app.fragments.CountriesFragment"
        tools:layout="@layout/fragment_countries" />

    <fragment
        android:id="@+id/navigation_main_categories_fragment"
        android:name="com.test.app.fragments.CategoriesFragment"
        tools:layout="@layout/fragment_categories" />

</navigation>




Answer 1

您可以使用以下代码作为起点和终点

val navHostFragment = (supportFragmentManager.findFragmentById(R.id.home_nav_fragment) as NavHostFragment)
val inflater = navHostFragment.navController.navInflater
val graph = inflater.inflate(R.navigation.nav_main)
graph.startDestination = R.id.fragment1

navHostFragment.navController.graph = graph

Answer 2

尝试此代码

// Configure the navigation
val navHost = nav_host_fragment as NavHostFragment
graph = navHost.navController.navInflater.inflate(R.navigation.nav_graph)
if(value == 0)
graph.startDestination = R.id.counriesFragment
else
grapgh.startDestination = R.id.categoryFragment


navHost.navController.graph = graph

NavigationUI.setupActionBarWithNavController(this, navHost.navController)