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我的问题是我的工具栏上的菜单项没有显示。具体来说，我有一个名为“设置”的菜单项，它封装了我想要在单击“设置”图标时显示的所有其他菜单项。但是，当单击该图标时，不会向用户显示其他菜单项的列表。

这是我的my_menu.xml：

<menu
    xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto">

    <item
        android:id="@+id/settings"
        app:showAsAction="always"
        android:icon="@drawable/ic_settings"
        android:title="@string/settings">

        <menu>
            <item
                android:id="@+id/loginFragment"
                android:menuCategory="secondary"
                android:icon="@drawable/ic_login"
                app:showAsAction="ifRoom"
                android:title="@string/loginOrLogout"/>

            <item
                android:id="@+id/firstFragment"
                android:icon="@drawable/ic_first_fragment_icon"
                android:menuCategory="secondary"
                app:showAsAction="ifRoom"
                android:title="@string/first_fragment_text"/>

            <item
                android:id="@+id/secondFragment"
                android:icon="@drawable/ic_second_fragment"
                android:menuCategory="secondary"
                app:showAsAction="ifRoom"
                android:title="@string/second_fragment_text"/>
        </menu>
    </item>
</menu>

这是我的MainActivity.kt课：

class MainActivity : AppCompatActivity() {

    private lateinit var binding: ActivityMainBinding
    private val navController by lazy{ findNavController(R.id.myNavHostFragment)}

    private val appBarConfiguration by lazy {
        AppBarConfiguration(setOf(R.id.firstFragment), binding.drawerLayout)
    }

    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)
        binding = DataBindingUtil.setContentView(this, R.layout.activity_main)
        binding.lifecycleOwner = this

        setSupportActionBar(binding.toolbar)
        setupNavigationComponents(navController)
        setupNavControllerListener()
    }

    private fun setupNavigationComponents(navController: NavController) {
        binding.apply {
            toolbar.setupWithNavController(navController, appBarConfiguration)
            navView?.setupWithNavController(navController)
            bottomNavView?.setupWithNavController(navController)
        }
    }

    private fun setupNavControllerListener() {
        navController.addOnDestinationChangedListener { _, destination, _ ->

            if(destination.id in arrayOf(
                    R.id.firstFragment)){
                toolbar.visibility = View.GONE
                bottom_nav_view?.visibility = View.GONE
                nav_view?.visibility = View.GONE
            }else{
                toolbar.visibility = View.VISIBLE
                bottom_nav_view?.visibility = View.VISIBLE
                nav_view?.visibility = View.VISIBLE
            }
        }
    }

    override fun onCreateOptionsMenu(menu: Menu?): Boolean {
        menuInflater.inflate(R.menu.my_menu, menu)
        return super.onCreateOptionsMenu(menu)
    }

    override fun onOptionsItemSelected(item: MenuItem): Boolean =
        /*
        * Have the NavigationUI look for an action or destination matching the menu
        * item id and navigate there if found.
        * Otherwise, bubble up to the parent.
        * */
        item.onNavDestinationSelected(findNavController(R.id.myNavHostFragment))
               || super.onOptionsItemSelected(item)

    override fun onSupportNavigateUp(): Boolean {
       // Allows NavigationUI to support proper up navigation or the drawer layout
       // drawer menu, depending on the situation
        return findNavController(R.id.myNavHostFragment).navigateUp(appBarConfiguration)
    }
}

在下面，我显示了屏幕右上角的屏幕截图，您可以在其中看到“设置”图标：

在此处输入图像描述

当我单击该图标时，我得到以下结果：

在此处输入图像描述

如您所见，没有向用户显示任何菜单项。奇怪的是，当我单击“打开的白框”内的某个位置时，应用程序会导航到相应的片段。但是项目没有显示，为什么？

我在这里做错了什么？

4

0 回答 0