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我正在尝试将 navController 设置为 bottomNavigation，但它需要活动，问题是我的 borromNavigation 托管在片段中，所以我没有活动实例。

我试过了

bottom_nav_view.setupWithNavController(findNavController())

和：

val host = Navigation.findNavController(this.activity!!.parent, R.id.my_nav_host_fragment)

bottom_nav_view.setupWithNavController(host)

home_fragment.xml：

<?xml version="1.0" encoding="utf-8"?>
<androidx.constraintlayout.widget.ConstraintLayout
        xmlns:android="http://schemas.android.com/apk/res/android"
        xmlns:tools="http://schemas.android.com/tools"
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        xmlns:app="http://schemas.android.com/apk/res-auto"
        tools:context=".ui.fragments.home.HomeFragment">

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

    <com.google.android.material.bottomnavigation.BottomNavigationView
            app:layout_constraintBottom_toBottomOf="parent"
            app:layout_constraintStart_toStartOf="parent"
            app:layout_constraintEnd_toEndOf="parent"
            android:id="@+id/bottom_nav_view"
            android:layout_width="match_parent"
            android:layout_height="wrap_content"
            app:menu="@menu/bottom_menu" />

</androidx.constraintlayout.widget.ConstraintLayout>

所以，我需要以某种方式my_nav_host_fragment从我home_fragment.xml的HomeFragment.kt

HomeFragment.kt

package andy.schedulekpi.ui.fragments.home

import androidx.lifecycle.ViewModelProviders
import android.os.Bundle
import android.util.Log
import androidx.fragment.app.Fragment
import android.view.LayoutInflater
import android.view.View
import android.view.ViewGroup
import android.widget.Toast
import androidx.navigation.NavController
import androidx.navigation.Navigation
import androidx.navigation.fragment.findNavController
import androidx.navigation.fragment.navArgs
import androidx.navigation.ui.NavigationUI
import androidx.navigation.ui.setupWithNavController

import andy.schedulekpi.R
import andy.schedulekpi.ui.fragments.start.StartFragmentDirections
import kotlinx.android.synthetic.main.home_fragment.*

class HomeFragment : Fragment() {

    companion object {
        fun newInstance() = HomeFragment()
    }

    private lateinit var viewModel: HomeViewModel
    private lateinit var host : NavController

    val safeArgs : HomeFragmentArgs by navArgs()

    override fun onCreateView(
        inflater: LayoutInflater, container: ViewGroup?,
        savedInstanceState: Bundle?
    ): View? {
        val view =  inflater.inflate(R.layout.home_fragment, container, false)

        //host = Navigation.findNavController(this.activity!!.parent, R.id.my_nav_host_fragment)

        return view
    }

    override fun onActivityCreated(savedInstanceState: Bundle?) {
        super.onActivityCreated(savedInstanceState)
        viewModel = ViewModelProviders.of(this).get(HomeViewModel::class.java)
        // TODO: Use the ViewModel
        Toast.makeText(this.context, safeArgs.currentWeek.toString(), Toast.LENGTH_SHORT).show()

        //val navController = Navigation.findNavController(activity!!.parent, R.id.my_nav_host_fragment) - don't work

        //val host = Navigation.findNavController()  -ERROR

       // bottom_nav_view.setupWithNavController(findNavController()) -ERROR


    }

}

底部菜单.xml：

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

    <item
            android:icon="@drawable/ic_schedule"
            android:id="@+id/scheduleFragment"
            android:title="Schedule"/>

    <item
            android:icon="@drawable/ic_database"
            android:id="@+id/archiveFragment"
            android:title="Database"/>
    <item
            android:id="@+id/teachersFragment"
            android:icon="@drawable/ic_teachers"
            android:title="Teachers"/>

    <item
            android:id="@+id/settingsFragment"
            android:icon="@drawable/ic_settings_"
            android:title="Settings"/>

</menu>

main_navigation.xml：

<?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/main_navigation"
            app:startDestination="@id/scheduleFragment">
    <fragment
            android:id="@+id/scheduleFragment"
            android:name="andy.schedulekpi.ui.fragments.schedule.ScheduleFragment"
            android:label="schedule_fragment"
            tools:layout="@layout/schedule_fragment"/>
    <fragment
            android:id="@+id/archiveFragment"
            android:name="andy.schedulekpi.ui.fragments.archive.ArchiveFragment"
            android:label="archive_fragment"
            tools:layout="@layout/archive_fragment"/>
    <fragment
            android:id="@+id/teachersFragment"
            android:name="andy.schedulekpi.ui.fragments.teachers.TeachersFragment"
            android:label="teachers_fragment"
            tools:layout="@layout/teachers_fragment"/>
    <fragment
            android:id="@+id/settingsFragment"
            android:name="andy.schedulekpi.ui.fragments.settings.SettingsFragment"
            android:label="settings_fragment"
            tools:layout="@layout/settings_fragment"/>

</navigation>

我希望从片段中处理bottomNavigation，但现在我点击了菜单项，没有发生任何事情或错误。

4

2 回答 2

1

在 HomeFragment 中在 BottomNavigationView 上设置 navController：

import androidx.navigation.findNavController

Navigation.setViewNavController(bottom_nav_view, activity!!.findNavController(R.id.my_nav_host_fragment))

然后当你想从 bottom_nav_view 获取 navController 时：

bottom_nav_view.findNavController()
于 2019-08-02T00:14:36.530 回答
1

正如Artur Gniewowski 所说，在 onActivityCreated 的 HomeFragment 中我只需要添加

bottom_nav_view.setupWithNavController(activity!!.findNavController(R.id.my_nav_host_fragment))

所以，现在在 HomeFragment 我有：

package andy.schedulekpi.ui.fragments.home

import androidx.lifecycle.ViewModelProviders
import android.os.Bundle
import androidx.fragment.app.Fragment
import android.view.LayoutInflater
import android.view.View
import android.view.ViewGroup
import android.widget.Toast
import androidx.navigation.Navigation
import androidx.navigation.findNavController
import androidx.navigation.fragment.navArgs
import androidx.navigation.ui.setupWithNavController

import andy.schedulekpi.R
import kotlinx.android.synthetic.main.home_fragment.*

import kotlinx.android.synthetic.main.home_fragment.view.*

class HomeFragment : Fragment() {

    companion object {
        fun newInstance() = HomeFragment()
    }

    private lateinit var viewModel: HomeViewModel


    val safeArgs : HomeFragmentArgs by navArgs()

    override fun onCreateView(
        inflater: LayoutInflater, container: ViewGroup?,
        savedInstanceState: Bundle?
    ): View? {
        val view =  inflater.inflate(R.layout.home_fragment, container, false)


        return view
    }

    override fun onActivityCreated(savedInstanceState: Bundle?) {
        super.onActivityCreated(savedInstanceState)
        viewModel = ViewModelProviders.of(this).get(HomeViewModel::class.java)
        // TODO: Use the ViewModel
        //Navigation.setViewNavController(bottom_nav_view, activity!!.findNavController(R.id.my_nav_host_fragment))
        bottom_nav_view.setupWithNavController(activity!!.findNavController(R.id.my_nav_host_fragment))

        Toast.makeText(this.context, safeArgs.currentWeek.toString(), Toast.LENGTH_SHORT).show()
    }

}

感谢Artur Gniewowski。

于 2019-08-02T02:52:55.473 回答