Android Material 3主题下修改返回按钮图标颜色的方法

我开发了一个单Activity应用，主题继承自Theme.Material3.DayNight。该Activity没有自定义Toolbar，配有Bottom Navigation，使用Jetpack Navigation库实现Fragment间导航。

导航到非底部导航对应的Fragment时，工具栏会出现返回箭头，点击可返回上一个Fragment，这符合预期，但我始终无法修改该箭头图标的颜色。

我尝试从Activity中获取supportActionBar并查找对应的视图，但未成功；也使用过布局检查器，但它仅显示工具栏下方的视图。

相关代码 #

Main Activity样式

<style name="Theme.MyTheme" parent="Theme.Material3.DayNight">
    ...
</style>

Main Activity布局

<?xml version="1.0" encoding="utf-8"?>
<androidx.constraintlayout.widget.ConstraintLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    xmlns:tools="http://schemas.android.com/tools"
    android:id="@+id/container"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    tools:context=".presentation.MainActivity">

    <androidx.fragment.app.FragmentContainerView
        android:id="@+id/fragment_container_view"
        android:name="androidx.navigation.fragment.NavHostFragment"
        android:layout_width="match_parent"
        android:layout_height="0dp"
        app:defaultNavHost="true"
        app:layout_constraintBottom_toTopOf="@+id/nav_view"
        app:layout_constraintLeft_toLeftOf="parent"
        app:layout_constraintRight_toRightOf="parent"
        app:layout_constraintTop_toTopOf="parent"
        app:navGraph="@navigation/nav_graph" />

    <com.google.android.material.bottomnavigation.BottomNavigationView
        android:id="@+id/nav_view"
        android:layout_width="0dp"
        android:layout_height="wrap_content"
        android:layout_marginStart="0dp"
        android:layout_marginEnd="0dp"
        app:itemActiveIndicatorStyle="@style/Honk.Custom.Indicator"
        app:layout_constraintBottom_toBottomOf="parent"
        app:layout_constraintLeft_toLeftOf="parent"
        app:layout_constraintRight_toRightOf="parent"
        app:menu="@menu/bottom_nav_menu" />

</androidx.constraintlayout.widget.ConstraintLayout>

Main Activity初始化代码

override fun onCreate(savedInstanceState: Bundle?) {
    super.onCreate(savedInstanceState)
    setupMainScreen()
}

private fun setupMainScreen() {
    binding = ActivityMainBinding.inflate(layoutInflater)
    setContentView(binding.root)
    val navView: BottomNavigationView = binding.navView
    val fragment = supportFragmentManager.findFragmentById(R.id.fragment_container_view)
    val navController = (fragment as NavHostFragment).navController
    val appBarConfiguration = AppBarConfiguration(
        setOf(R.id.navigation_clients, R.id.navigation_vehicles, R.id.navigation_settings)
    )
    setupActionBarWithNavController(navController, appBarConfiguration)
    findViewById<Toolbar>(androidx.appcompat.R.id.action_bar)

    navView.setupWithNavController(navController)
}

override fun onSupportNavigateUp(): Boolean {
    val fragment = supportFragmentManager.findFragmentById(R.id.fragment_container_view)
    val navController = (fragment as NavHostFragment).navController
    return navController.navigateUp() || super.onSupportNavigateUp()
}

方法1：通过主题属性直接修改（推荐） #

在你的Theme.MyTheme中添加Material3专属的返回箭头颜色属性，全局生效：

<style name="Theme.MyTheme" parent="Theme.Material3.DayNight">
    <!-- 修改返回箭头颜色 -->
    <item name="toolbarNavigationIconColor">@color/your_desired_color</item>
    <!-- 适配深色模式可单独设置夜间颜色 -->
    <item name="toolbarNavigationIconColorNight">@color/your_night_mode_color</item>
</style>

如果上述属性不生效，可尝试全局图标色调属性：

<style name="Theme.MyTheme" parent="Theme.Material3.DayNight">
    <item name="actionBarIconColor">@color/your_desired_color</item>
</style>

方法2：自定义Toolbar并绑定Navigation #

若主题属性修改无效，可添加自定义Toolbar到布局，手动控制样式：

1. 修改Activity布局，插入Toolbar：

<androidx.constraintlayout.widget.ConstraintLayout ...>

    <androidx.appcompat.widget.Toolbar
        android:id="@+id/custom_toolbar"
        android:layout_width="match_parent"
        android:layout_height="?attr/actionBarSize"
        app:layout_constraintTop_toTopOf="parent" />

    <androidx.fragment.app.FragmentContainerView
        android:id="@+id/fragment_container_view"
        ...
        app:layout_constraintTop_toBottomOf="@+id/custom_toolbar" />

    <!-- BottomNavigationView 保持不变 -->

</androidx.constraintlayout.widget.ConstraintLayout>

2. 在Activity中绑定Toolbar与Navigation，并修改箭头颜色：

private fun setupMainScreen() {
    binding = ActivityMainBinding.inflate(layoutInflater)
    setContentView(binding.root)
    val navView: BottomNavigationView = binding.navView
    val fragment = supportFragmentManager.findFragmentById(R.id.fragment_container_view)
    val navController = (fragment as NavHostFragment).navController
    
    // 设置自定义Toolbar为ActionBar
    val toolbar = binding.customToolbar
    setSupportActionBar(toolbar)
    
    val appBarConfiguration = AppBarConfiguration(
        setOf(R.id.navigation_clients, R.id.navigation_vehicles, R.id.navigation_settings)
    )
    // 绑定Navigation控制器
    toolbar.setupWithNavController(navController, appBarConfiguration)
    
    // 修改返回箭头颜色
    toolbar.navigationIcon?.setTint(ContextCompat.getColor(this, R.color.your_desired_color))
    
    navView.setupWithNavController(navController)
}

方法3：通过导航监听器动态修改 #

如果需要根据不同Fragment切换箭头颜色，可添加导航监听：

private fun setupMainScreen() {
    // ... 其他初始化代码
    
    navController.addOnDestinationChangedListener { _, destination, _ ->
        supportActionBar?.let { actionBar ->
            val drawable = actionBar.homeAsUpIndicator
            drawable?.let {
                val color = when (destination.id) {
                    R.id.target_fragment_1 -> ContextCompat.getColor(this, R.color.red)
                    R.id.target_fragment_2 -> ContextCompat.getColor(this, R.color.blue)
                    else -> ContextCompat.getColor(this, R.color.default_color)
                }
                it.setTint(color)
                actionBar.setHomeAsUpIndicator(it)
            }
        }
    }
}

布局检查器使用技巧 #

系统默认ActionBar属于DecorView层级，之前看不到是因为没展开顶层结构。在布局检查器中依次展开：DecorView -> LinearLayout -> ActionBarContainer -> Toolbar，就能找到返回箭头对应的AppCompatImageView，可查看它的当前属性排查问题。

内容的提问来源于stack exchange，提问作者Leonardo Sibela