如何从片段管理bottomNavigation?

问题描述

我正在尝试将navController设置为bottomNavigation，但这需要活动，问题是我的borromNavigation托管在片段中，因此我没有活动实例.

I'm trying to set navController to bottomNavigation, but it's requires activity, the problem is my borromNavigation hosted in fragment, so i don't have activity instance.

我尝试过

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:

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>

因此，我需要以某种方式从我的 homeFragment.kt

So, I need somehow take my_nav_host_fragment from my home_fragment.xml in HomeFragment.kt

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


    }

}

bottom_menu.xml:

bottom_menu.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:

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>

我本来希望处理片段中的bottomNavigation，但是现在我单击了菜单项，没有任何反应或出错.

I expected to handle bottomNavigation from fragment, but now i clicked on menu items and nothing happend or error.

推荐答案

在HomeFragment中在BottomNavigationView上设置navController:

In HomeFragment to set navController on BottomNavigationView:

import androidx.navigation.findNavController

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

然后，当您要从bottom_nav_view获取navController时:

then when u want get navController from bottom_nav_view:

bottom_nav_view.findNavController()

这篇关于如何从片段管理bottomNavigation?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！