使用 Navigation - Kotlin 从工具栏菜单项单击的片段之间传递数据

Question

我已经使用导航架构组件设置了我的应用程序。从一个片段导航到下一个片段工作正常。但是，我无法尝试在该导航流程中传递数据。

按照 Navigation codelab app 的结构，我使用下面的代码在单击菜单项时从一个片段导航到另一个片段：

MainActivity.kt

override fun onOptionsItemSelected(item: MenuItem): Boolean {
    return NavigationUI.onNavDestinationSelected(item,
        Navigation.findNavController(this, R.id.nav_host_fragment))
        || super.onOptionsItemSelected(item)
}

我尝试通过如下修改代码来将包传递到这里。 Android Studio 未检测到任何错误，但当我尝试执行该菜单项单击时，我的应用程序崩溃了。请注意，我将 R.id.menu_edit 作为 findNavController 中的参数传递，否则我会收到“没有为参数 'viewId' 传递任何值”构建错误 - 但我认为您通常会在不传递任何内容的情况下调用它.

override fun onOptionsItemSelected(item: MenuItem): Boolean {
    when (item?.itemId) {
        R.id.menu_song_edit -> {
            val songBundle = Bundle()
            songBundle.putString("titleArg", song_title.toString())
            this.findNavController(R.id.menu_song_edit).navigate(R.id.goto_songedit, songBundle) // *** this is line 96 where it crashes per the log ***
            return true
        }
        else -> return NavigationUI.onNavDestinationSelected(item,
                Navigation.findNavController(this, R.id.nav_host_fragment))
                || super.onOptionsItemSelected(item)
    }
}

从下面的崩溃记录。找不到 NavController？

E/AndroidRuntime: FATAL EXCEPTION: main
    Process: com.projects.arise.mytestapp, PID: 1162
    java.lang.IllegalStateException: Activity com.projects.arise.mytestapp.MainActivity@58f00cb does not have a NavController set on 2131230836
        at androidx.navigation.Navigation.findNavController(Navigation.java:60)
        at androidx.navigation.ActivityKt.findNavController(Activity.kt:30)
        at com.projects.arise.mytestapp.MainActivity.onOptionsItemSelected(MainActivity.kt:96)
        at android.app.Activity.onMenuItemSelected(Activity.java:3204)
        at android.support.v4.app.FragmentActivity.onMenuItemSelected(FragmentActivity.java:407)
        at android.support.v7.app.AppCompatActivity.onMenuItemSelected(AppCompatActivity.java:195)
        at android.support.v7.view.WindowCallbackWrapper.onMenuItemSelected(WindowCallbackWrapper.java:108)
        at android.support.v7.view.WindowCallbackWrapper.onMenuItemSelected(WindowCallbackWrapper.java:108)
        at android.support.v7.app.ToolbarActionBar.onMenuItemClick(ToolbarActionBar.java:63)
        at android.support.v7.widget.Toolbar.onMenuItemClick(Toolbar.java:203)
        at android.support.v7.widget.ActionMenuView$MenuBuilderCallback.onMenuItemSelected(ActionMenuView.java:780)
        at android.support.v7.view.menu.MenuBuilder.dispatchMenuItemSelected(MenuBuilder.java:822)
        at android.support.v7.view.menu.MenuItemImpl.invoke(MenuItemImpl.java:171)
        at android.support.v7.view.menu.MenuBuilder.performItemAction(MenuBuilder.java:973)
        at android.support.v7.view.menu.MenuBuilder.performItemAction(MenuBuilder.java:963)
        at android.support.v7.widget.ActionMenuView.invokeItem(ActionMenuView.java:624)
        at android.support.v7.view.menu.ActionMenuItemView.onClick(ActionMenuItemView.java:150)
        at android.view.View.performClick(View.java:5610)
        at android.view.View$PerformClick.run(View.java:22265)
        at android.os.Handler.handleCallback(Handler.java:751)
        at android.os.Handler.dispatchMessage(Handler.java:95)
        at android.os.Looper.loop(Looper.java:154)
        at android.app.ActivityThread.main(ActivityThread.java:6077)
        at java.lang.reflect.Method.invoke(Native Method)
        at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:866)
        at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:756) Disconnected from the target VM, address: 'localhost:8610', transport: 'socket'

然后我尝试在传递数据的片段中覆盖 onOptionsItemSelected，但这似乎没有任何效果。我猜那是因为它已经被上面 MainActivity.kt 中的相同方法拦截了。

我在数据发送片段中的代码如下。资源ID'goto_detailsedit'指的是导航nav_graph.xml文件中action的ID。

override fun onOptionsItemSelected(item: MenuItem?): Boolean {
    when (item?.itemId) {
        R.id.menu_edit -> {
            val songBundle = Bundle()
            songBundle.putString("nameArg", first_name.text.toString())
            this.findNavController().navigate(R.id.goto_songedit, songBundle)
            return true
        }
        else -> return super.onOptionsItemSelected(item)
    }
}

有人可以帮我解决上面 MainActivity.kt 代码中的菜鸟语法错误吗？

2018 年 7 月 2 日更新

再次浏览 documentation 我发现语法应该如下 - 我需要引用一个视图：

view.findNavController().navigate(R.id.confirmationAction, bundle)

我已经在 onCreate 中设置了主 activity 中的工具栏，方法是调用：

val toolbar = findViewById<Toolbar>(R.id.toolbar)
    setSupportActionBar(toolbar)

所以我尝试通过将 this 替换为 toolbar 来引用工具栏：

toolbar.findNavController().navigate(R.id.goto_songedit, songBundle)

Android Studio 代码编辑器现在很满意，但我的应用程序仍然崩溃。日志指出 NavController 尚未设置：

E/AndroidRuntime: FATAL EXCEPTION: main
    Process: com.projects.arise.mytestapp, PID: 2670
    java.lang.IllegalStateException: View android.support.v7.widget.Toolbar{d03bbdd V.E...... ........ 0,0-1080,147 #7f0800e0 app:id/toolbar} does not have a NavController set
        at androidx.navigation.Navigation.findNavController(Navigation.java:83)
        at androidx.navigation.ViewKt.findNavController(View.kt:28)
        at com.projects.arise.mytestapp.MainActivity.onOptionsItemSelected(MainActivity.kt:96)
        ...

有什么我想念的吗？或者这可能是导航的错误？

Answer 1

你应该使用 'NavHostFragment.findNavController()':

    override fun onOptionsItemSelected(item: MenuItem?): Boolean {
    when (item?.itemId) { 
        R.id.menu_edit -> { 
            val songBundle = Bundle() 
            songBundle.putString("nameArg", first_name.text.toString()) 
            NavHostFragment.findNavController(nav_host_fragment).navigate(R.id.goto_songedit, songBundle) 
            return true 
        } 
        else -> return super.onOptionsItemSelected(item) 
    } 
}

Answer 2

完美解决方案：

//-------------------/To send Data/--------------------

   val bundle = Bundle()
     bundle.putString("data","Hello World!")
     Navigation.findNavController(view).navigate(R.id.action_firstFragment_to_secondFragment,bundle)


//--------------------/To get data/----------------------------------

 val string = arguments!!.getString("data")
Toast.makeText(context,string,Toast.LENGTH_SHORT).show()

使用 Navigation - Kotlin 从工具栏菜单项单击的片段之间传递数据

Passing data between fragments from toolbar menu item click using Navigation - Kotlin

navigation

parameter-passing

android-fragments

kotlin

android-toolbar