Question

我在MainActivity中有四个导航。

home_navigation （homeFragment-> homereportFragment）

device_navigation （devicefragment-> deviceUserFragment-> deviceScanFragment）

和config_navigation，automation_navigation ..

我想移到homeFragment中的deviceUserFragment

 <androidx.constraintlayout.widget.ConstraintLayout
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    tools:context=".view.main.MainActivity">

    <com.google.android.material.bottomnavigation.BottomNavigationView
        android:id="@+id/bottom_nav"
        android:layout_width="0dp"
        android:layout_height="wrap_content"
        app:layout_constraintEnd_toEndOf="parent"
        app:layout_constraintStart_toStartOf="parent"
        app:layout_constraintTop_toTopOf="parent"
        app:menu="@menu/menu_bottom" />

    <androidx.viewpager2.widget.ViewPager2
        android:id="@+id/slider_main"
        android:layout_width="0dp"
        android:layout_height="0dp"
        app:layout_constraintBottom_toBottomOf="parent"
        app:layout_constraintEnd_toEndOf="parent"
        app:layout_constraintStart_toStartOf="parent"
        app:layout_constraintTop_toBottomOf="@+id/bottom_nav" />

</androidx.constraintlayout.widget.ConstraintLayout>

private val mOnNavigationItemselectedListener =
    BottomNavigationView.OnNavigationItemSelectedListener { item ->
        when (item.itemId) {
            R.id.home_navigation -> {
                slider_main.currentItem = 0
                return@OnNavigationItemSelectedListener true
            }
            R.id.device_navigation -> {
                slider_main.currentItem = 1
                return@OnNavigationItemSelectedListener true
            }
            R.id.automation_navigation -> {
                slider_main.currentItem = 2
                return@OnNavigationItemSelectedListener true
            }
            R.id.config_navigation -> {
                slider_main.currentItem = 3
                return@OnNavigationItemSelectedListener true
            }
        }
        false
    }


private val onpage = object : ViewPager2.OnPageChangeCallback() {
    override fun onPageScrollStateChanged(state: Int) {

    }

    override fun onPageScrolled(
        position: Int,
        positionOffset: Float,
        positionOffsetPixels: Int
    ) {

    }

    override fun onPageSelected(position: Int) {
        bottom_nav.menu.getItem(position).isChecked = true
    }

}




private fun initViewPager() {
    viewpagerAdapter = SliderAdapterMain(this)
    slider_main.apply {
        adapter = viewpagerAdapter
        registerOnPageChangeCallback(onpage)
    }
    bottom_nav.setOnNavigationItemSelectedListener(mOnNavigationItemselectedListener)
}

带有viewPager2和底部导航的MainActivity代码

home_reistdevice_button.setOnClickListener {
        activity!!.bottom_nav.selectedItemId = R.id.device_navigation
    }

它是homeFragment中的按钮。但是按钮会导致deviceFragment。

我试图在home_navigation图中添加deviceUserFragment。但这不适用于底部导航项。

我认为我应该将值homeFragment传递给deviceFragment。

因此，如果deiviceFragment获得价值，请在deviceFragment启动后立即导航至deviceUserFragment。

但是我不知道如何在底部导航项选择中传递值。

有人告诉我怎么做。

或者告诉我最好的方法。

@Edit 2020-09-03 我找到了解决方案。解决方法是在ContainerBragmnet中添加onBacklistener

class HomeContainerFragment : Fragment() {

private var navController:NavController?=null

override fun onCreateView(
    inflater: LayoutInflater, container: ViewGroup?,
    savedInstanceState: Bundle?
): View? {
    // Inflate the layout for this fragment
    return inflater.inflate(R.layout.fragment_home_container, container, false)
}

override fun onViewCreated(view: View, savedInstanceState: Bundle?) {
    super.onViewCreated(view, savedInstanceState)

    val navHostFragment = childFragmentManager.findFragmentById(R.id.home_nav_host) as NavHostFragment?

    navController = navHostFragment?.navController

    listenOnBackPressed()


}

private fun listenOnBackPressed(){
    requireActivity().onBackPressedDispatcher.addCallback(viewLifecycleOwner,callback)
}

override fun onResume() {
    super.onResume()
    callback.isEnabled = true
}

override fun onPause() {
    super.onPause()
    callback.isEnabled =false
}
private fun dialog_build(){
    val builder = AlertDialog.Builder(ContextThemeWrapper(activity, R.style.AlertDialog))
    builder.setTitle("App terminate")
    builder.setMessage("Are you terminating APP?")

    builder.setPositiveButton("terminate") { _, _ ->
        activity?.finishAffinity()
    }
    builder.setNegativeButton("cancel") { _, _ ->

    }

    builder.show()
}

val callback = object : OnBackPressedCallback(false) {
    override fun handleOnBackPressed() {
        var backkeytime: Long = 0
        lateinit var toast: Toast

        if(navController?.currentDestination?.id == navController?.graph?.startDestination){
            isEnabled = false
            dialog_build()
            isEnabled = true
        }
        else{
            navController?.navigateUp()
        }

    }
}

}

我的整个项目结构是1个活动4个ContainerFragment（4个导航）

MainActivity（ViewPager2，BottomNavigation）

HomeContainerFragment（FragmentContainerView-home_navigation）

（在导航中）-HomeFragment -HomeReportFragment
-..
DeviceContainerFragment
...

android导航组件使用viewpager2和底部导航导航到其他图形中的片段

0 个答案: