BottomNavigationView与Navigation架构组件结合使用时，setupWithNavController不生效问题解决

最近学习jetpack Navigation导航组件时，用BottomNavigationView与Navigation配合完成主页单activity与多fragment导航功能，一切准备就绪，却发现通过BottomNavigationView扩展方法来关联BottomNavigationView与Navigation时不生效，activity代码如下：

package com.dylan.jetpackusage

import android.os.Bundle
import androidx.appcompat.app.AppCompatActivity
import androidx.navigation.findNavController
import androidx.navigation.ui.setupWithNavController
import kotlinx.android.synthetic.main.activity_navigation.*

/**
 * Created by Dylan on 2021/7/2.
 * E-mail: andev.hoo@gmail.com
 * desc:
 */
 
class NavigationActivity : AppCompatActivity() {
    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)
        setContentView(R.layout.activity_navigation)
        supportActionBar?.hide()
        val navController = findNavController(R.id.fragmentContainerFcv)
//            supportFragmentManager.findFragmentById(R.id.fragmentContainerFcv)!!.findNavController()

       /* bottomNavigationViewBnv.setOnNavigationItemSelectedListener { menuItem ->
            Log.e("NavigationActivity", "menu id: ${menuItem.itemId}")
            Log.e("NavigationActivity", "group id: ${menuItem.groupId}")
            when (menuItem.itemId) {
                R.id.nav_home -> navController.navigate(R.id.nav_home)
                R.id.nav_message -> navController.navigate(R.id.nav_message)
                R.id.nav_mine -> navController.navigate(R.id.nav_mine)
            }
            return@setOnNavigationItemSelectedListener true
        }*/
        bottomNavigationViewBnv.setupWithNavController(navController)


    }
}

activity的布局文件activity_navigation代码如下：

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout 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:layout_width="match_parent"
    android:layout_height="match_parent"
    android:orientation="vertical"
    tools:context=".NavigationActivity">

    <fragment
        android:id="@+id/fragmentContainerFcv"
        android:name="androidx.navigation.fragment.NavHostFragment"
        android:layout_width="match_parent"
        android:layout_height="0dp"
        android:layout_weight="1"
        android:background="#f9f9f9"
        app:navGraph="@navigation/nav_graph" />

    <View
        android:layout_width="match_parent"
        android:layout_height="1dp"
        android:background="#DDD9D9" />

    <com.google.android.material.bottomnavigation.BottomNavigationView
        android:id="@+id/bottomNavigationViewBnv"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:background="?android:attr/windowBackground"
        app:menu="@menu/bottom_nav_menu" />


</LinearLayout>

导航图文件nav_graph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/nav_graph"
    app:startDestination="@id/nav_home_frag">
    <fragment
        android:id="@+id/nav_home_frag"
        android:name="com.dylan.jetpackusage.fragment.HomeFragment"
        android:label="@string/main_page"
        tools:layout="@layout/fragment_home" />

    <fragment
        android:id="@+id/nav_message_frag"
        android:name="com.dylan.jetpackusage.fragment.MsgFragment"
        android:label="@string/msg"
        tools:layout="@layout/fragment_msg" />

    <fragment
        android:id="@+id/nav_mine_frag"
        android:name="com.dylan.jetpackusage.fragment.MineFragment"
        android:label="@string/mine"
        tools:layout="@layout/fragment_mine" />

</navigation>

选项菜单bottom_nav_menu如下：

<?xml version="1.0" encoding="utf-8"?>
<menu xmlns:android="http://schemas.android.com/apk/res/android">
    <item
        android:id="@+id/nav_home"
        android:icon="@drawable/ic_home_black_24dp"
        android:title="@string/main_page" />

    <item
        android:id="@+id/nav_message"
        android:icon="@drawable/ic_notifications_black_24dp"
        android:title="@string/msg" />

    <item
        android:id="@+id/nav_mine"
        android:icon="@drawable/ic_dashboard_black_24dp"
        android:title="@string/mine" />

</menu>

运行效果如下：

运行之后发现点击底部导航按钮，没有切换到对应fragment，最后排查到，是因为nav_graph导航图中的fragment的id没有与bottom_nav_menu选项菜单中item的id一一对应，将其一一对应即可，这里将nav_graph中fragment的id进行修改，与bottom_nav_menu的保持一致，修改后的代码如下：

<?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/nav_graph"
    app:startDestination="@id/nav_home">
    <fragment
        android:id="@+id/nav_home"
        android:name="com.dylan.jetpackusage.fragment.HomeFragment"
        android:label="@string/main_page"
        tools:layout="@layout/fragment_home" />

    <fragment
        android:id="@+id/nav_message"
        android:name="com.dylan.jetpackusage.fragment.MsgFragment"
        android:label="@string/msg"
        tools:layout="@layout/fragment_msg" />

    <fragment
        android:id="@+id/nav_mine"
        android:name="com.dylan.jetpackusage.fragment.MineFragment"
        android:label="@string/mine"
        tools:layout="@layout/fragment_mine" />

</navigation>

修改之后，就可以将BottomNavigationView与Navigation进行关联，点击底部选项卡自动切换到对应fragment了。

小结

BottomNavigationView的menu的item的id需要与Navigation的对应的fragment的id保持一致，才能通过*bottomNavigationViewBnv.setupWithNavController(navController)*进行自动关联。