Question

使用NavHostFragment时，我试图（没有成功）更改工具栏上的后退箭头图标。我正在将NavController用于工具栏（如您在此处看到的那样）

override fun onCreate(savedInstanceState: Bundle?) {
    super.onCreate(savedInstanceState)
    setContentView(R.layout.activity_main)
    setSupportActionBar(toolbar)
    val navController = findNavController(R.id.nav_host_fragment)
    appBarConfiguration = AppBarConfiguration(navController.graph)
    setupActionBarWithNavController(navController, appBarConfiguration)
    navigation.setOnNavigationItemSelectedListener(mOnNavigationItemSelectedListener)
    toolbar.setTitleTextColor(resources.getColor(R.color.toolbarTextColor))
    navigation.setupWithNavController(Navigation.findNavController(this, R.id.nav_host_fragment))
}

导航正常，但我似乎无法更改后退图标。

我已经尝试使用自定义主题。到目前为止，定义的属性都没有起作用。

    <style name="ToolbarTheme" parent="@style/ThemeOverlay.AppCompat.ActionBar">
        <item name="android:navigationIcon">@drawable/ic_keyboard_arrow_left_black_24dp</item>
        <item name="android:homeAsUpIndicator">@drawable/ic_keyboard_arrow_left_black_24dp</item>
        <item name="collapseIcon">@drawable/ic_keyboard_arrow_left_black_24dp</item>
        <item name="android:closeIcon">@drawable/ic_keyboard_arrow_left_black_24dp</item>
    </style>

尝试使用代码：

toolbar.navigationIcon = resources.getDrawable(R.drawable.ic_keyboard_arrow_left_black_24dp)
toolbar.setNavigationIcon(R.drawable.ic_keyboard_arrow_left_black_24dp)
toolbar.navigationIconResource = R.drawable.ic_keyboard_arrow_left_black_24dp

使用代码时，一旦创建了布局，就会出现后退按钮，但是当我输入另一个片段时，该图标会变回默认的后退图标。

我该如何更改？

Answer 1

此功能应在将来添加，目前可以通过实现“ OnDestinationChangedListener”并更改回调中的工具栏图标（只需确保在设置方法之后添加“ OnDestinationChangedListener”）来实现。：

navController.addOnDestinationChangedListener { controller, destination, arguments ->
        toolbar.setNavigationIcon(R.drawable.ic_keyboard_arrow_left_black_24dp) //set it here for all the destinations, or inside the switch statement if you want to change it based on destination
        when(destination.id) {
            R.id.mainFragment -> {
              toolbar.setNavigationIcon(R.drawable.ic_keyboard_arrow_left_black_24dp)
            }
            R.id.detailsFragment -> {
              toolbar.setNavigationIcon(R.drawable.ic_keyboard_arrow_left_black_24dp)
            }
        }
    }

基于此问题：

https://issuetracker.google.com/issues/121078028

使用navhost时无法更改工具栏的后退图标

1 个答案: