如果我点击导航控制器中的菜单，如何在两个片段目的地之间传递数据？

Question

我正在尝试使用导航控制器。我有一个底部导航视图。位于我的 MainActivity 上，它是使用以下代码启动的：

class MainActivity : AppCompatActivity() {

    lateinit var navController : NavController
    lateinit var logoHeaderImageView : ImageView
    var toolbarMenu : Menu? = null


    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)
        setContentView(R.layout.activity_main)

        logoHeaderImageView = findViewById(R.id.header_lakuin_image_view)

        navController = Navigation.findNavController(this,R.id.nav_main_host_fragment)



        setupBottomNavMenu(navController)
        setupActionBar(navController)



    }

    fun setupBottomNavMenu(navController: NavController) {
        NavigationUI.setupWithNavController(bottom_navigation_view,navController)
    }

    fun setupActionBar(navController: NavController) {
        setSupportActionBar(main_activity_toolbar)
        main_activity_toolbar.title = ""


        val appBarConfiguration = AppBarConfiguration(
            setOf(
                // set some destination as the top hierarchy destination, to make the up button doesn't show.
                R.id.destination_home,
                R.id.destination_order,
                R.id.destination_favourite,
                R.id.destination_cart,
                R.id.destination_profile

            ))

        NavigationUI.setupWithNavController(main_activity_toolbar,navController,appBarConfiguration)
    }


    override fun onCreateOptionsMenu(menu: Menu?): Boolean {
        menuInflater.inflate(R.menu.menu_main_toolbar, menu)
        toolbarMenu = menu
        return true
    }

    override fun onOptionsItemSelected(item: MenuItem): Boolean {
        return item.onNavDestinationSelected(navController) || super.onOptionsItemSelected(item)
    }




}

这是我的底部导航视图的外观：

所以我想将数据从我的 HomeFragment（目的地家庭）传递到 OderFragment（目的地订单）。我通常使用 bundle 或 safeArgs 来传递数据，如下面的代码：

var bundle = bundleOf("amount" to amount)
view.findNavController().navigate(R.id.confirmationAction, bundle)

但我不知道该代码放在哪里，如果我想将数据从我的 HomeFragment 传递到 OderFragment

Answer 1

Post data:
Fragment fragment = new OderFragment();
                Bundle bundle = new Bundle();
                bundle.putString("key", "value");
                fragment.setArguments(bundle);

                FragmentTransaction transaction = getActivity().getSupportFragmentManager().beginTransaction();
                transaction.replace(R.id.frame_container, fragment);
                transaction.addToBackStack(null);
                transaction.commit();

Receive data:
Bundle bundle = this.getArguments();
            if (bundle != null) {
                myInt = bundle.getString("key");
            }

Answer 2

就这样:

override fun onOptionsItemSelected(item: MenuItem): Boolean {
    val bundle = Bundle()
    bundle.putString("myname","Hussnain")
    return when(item.itemId){
        R.id.aboutFragment ->{
            navController.navigate(R.id.aboutFragment,bundle)
            return true
    }else -> {
            NavigationUI.onNavDestinationSelected(item,navController) || super.onOptionsItemSelected(item)
        }
    }
}

导航：

 <fragment android:id="@+id/aboutFragment"
 android:name="com.cinderellaman.general.ui.fragments
 .AboutFragment"
  android:label="about_fragment"
  tools:layout="@layout/about_fragment">
  <argument android:name="myname" app:argType="string"/>
</fragment>

片段：

val args: AboutFragmentArgs by navArgs()
name.text = args.myname

Answer 3

使用 NavigationUI.setupWithNavController(bottom_navigation_view,navController) 时（或者，如果您使用 navigation-ui-ktx Kotlin 扩展 bottom_navigation_view.setupWithNavController(navController)），您不能将任何自定义参数传递给目标 - 这是全局导航是他们总是把你带到同一个屏幕同一个状态。

通常，您应该将当前数量之类的数据与导航参数分开保存 - 无论它是在持久化数据库、SharedPreferences 中，还是在进程终止后仍然存在的其他位置，允许用户继续他们正在做的事情即使在重新启动 phone 等

之后

但是，如果您必须为此使用导航参数，您可以提前为目的地设置默认参数（即，每当您的数量发生变化时）：

NavDestination orderDestination = navController.graph.findNode(R.id.destination_order)
orderDestination.addArgument("amount", NavArgument.Builder()
    .setType(NavType.FloatType)
    .setDefaultValue(amount)
    .build())

之后，您的 BottomNavigationView 触发 R.id.destination_order 将默认自动包含该参数以及您的新 amount 值。

Answer 4

您可以在片段之间使用共享的 ViewModel：

class SharedViewModel : ViewModel() {
    val selected = MutableLiveData<Item>()

    fun select(item: Item) {
        selected.value = item
    }
}

class MasterFragment : Fragment() {

    private lateinit var itemSelector: Selector

    private lateinit var model: SharedViewModel

    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)
        model = activity?.run {
            ViewModelProviders.of(this).get(SharedViewModel::class.java)
        } ?: throw Exception("Invalid Activity")
        itemSelector.setOnClickListener { item ->
            // Update the UI
        }
    }
}

class DetailFragment : Fragment() {

    private lateinit var model: SharedViewModel

    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)
        model = activity?.run {
            ViewModelProviders.of(this).get(SharedViewModel::class.java)
        } ?: throw Exception("Invalid Activity")
        model.selected.observe(this, Observer<Item> { item ->
            // Update the UI
        })
    }
}

可在此处找到更多信息：

https://developer.android.com/topic/libraries/architecture/viewmodel#sharing

Answer 5

Call Nav contoller from current fragment. And pass data as a bundle

Ex:
First fragment -
val bundle = Bundle()
            bundle.putString("crs",crs); //This is the passing parameter
            findNavController().navigate(R.id.action_Classes_to_AddUpdateStudents,bundle)
//Amend your parameter as a second argument

Second fragment -
crs = arguments?.getString("crs").toString() 
//Retrieve the data as u usually do with an activiy