我想用appbottombar实现导航，我的目标是无论我在应用程序中有什么页面，都应该有返回按钮来导航，除了主页，我该如何实现？我尝试了 navgraph host 但无法成功，我正在谷歌搜索但找不到合适的解决方案，如果有人可以提供帮助，请发表评论或写一些建议
活动代码：
class MainActivity : AppCompatActivity() {
private val profilePageFragment = ProfilePageFragment()
private val homePageFragment = HomePageFragment()
private val promoPageFragment = PromoPageFragment()
private val newsPageFragment = NewsPageFragment()
override fun onCreate(savedInstanceState: Bundle?) {
super.onCreate(savedInstanceState)
val binding =
DataBindingUtil.setContentView<ActivityMainBinding>(this,R.layout.activity_main)
// setSupportActionBar(binding.toolbar)
// val navController = this.findNavController(R.id.myNavHostFragment)
// NavigationUI.setupActionBarWithNavController(this, navController)
replaceFragment(homePageFragment)
binding.bottomNavigation.setOnNavigationItemSelectedListener{
when (it.itemId) {
R.id.hometPage -> replaceFragment(homePageFragment)
R.id.promotionPage -> replaceFragment(promoPageFragment)
R.id.newsPage -> replaceFragment(newsPageFragment)
R.id.profile -> replaceFragment(profilePageFragment)
}
true
}
}
// override fun onSupportNavigateUp(): Boolean {
// val navController = this.findNavController(R.id.myNavHostFragment)
// return navController.navigateUp()
// }
private fun replaceFragment(fragment: Fragment){
if(fragment !=null){
val transaction = supportFragmentManager.beginTransaction()
transaction.replace(R.id.bottom_navigation,fragment)
transaction.commit()
}
}
}
XML 代码：
<?xml version="1.0" encoding="utf-8"?>
<layout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:app="http://schemas.android.com/apk/res-auto">
<data>
<variable
name="mainActivity"
type="com.example.navigation.MainActivity" />
</data>
<androidx.constraintlayout.widget.ConstraintLayout
android:id="@+id/constraint"
android:layout_width="match_parent"
android:layout_height="match_parent">
<com.google.android.material.bottomnavigation.BottomNavigationView
android:id="@+id/bottom_navigation"
android:layout_width="match_parent"
android:layout_height="wrap_content"
app:layout_constraintBottom_toBottomOf="parent"
app:layout_constraintLeft_toLeftOf="parent"
app:layout_constraintRight_toRightOf="parent"
app:menu="@menu/menu"
titleLabelText="true"
app:itemRippleColor="@color/white" />
<!-- <fragment-->
<!-- android:id="@+id/myNavHostFragment"-->
<!-- android:name="androidx.navigation.fragment.NavHostFragment"-->
<!-- android:layout_width="match_parent"-->
<!-- android:layout_height="match_parent"-->
<!-- app:navGraph="@navigation/navigation"-->
<!-- titleLabelText="dasdasdsa"-->
<!-- app:defaultNavHost="true">-->
<!-- </fragment>-->
<FrameLayout
android:id="@+id/fragment_container"
android:layout_width="match_parent"
android:layout_height="match_parent"
app:layout_constraintTop_toTopOf="parent"
app:layout_constraintBottom_toTopOf="@+id/bottom_navigation"/>
</androidx.constraintlayout.widget.ConstraintLayout>
</layout>
