TextInputLayout下拉菜单实例化失败问题求助

给com.google.android.material.textfield.TextInputLayout设置style="@style/Widget.MaterialComponents.TextInputLayout.OutlinedBox.ExposedDropdownMenu"时，出现「Failed to instantiate one or more classes」错误，无法正常预览布局。

错误详情 #

无法实例化以下类：

• com.google.android.material.textfield.TextInputLayout（Open Class, Show Exception, Clear Cache）

提示：在自定义视图中使用View.isInEditMode()，在IDE展示时跳过代码或显示示例数据。如果这是意外错误，也可以尝试构建项目，然后手动刷新布局。

异常栈 #

java.lang.IllegalArgumentException: The style on this component requires your app theme to be Theme.MaterialComponents (or a descendant).
at com.google.android.material.internal.ThemeEnforcement.checkTheme(ThemeEnforcement.java:247)
at com.google.android.material.internal.ThemeEnforcement.checkMaterialTheme(ThemeEnforcement.java:216)
at com.google.android.material.internal.ThemeEnforcement.checkCompatibleTheme(ThemeEnforcement.java:144)
at com.google.android.material.internal.ThemeEnforcement.obtainTintedStyledAttributes(ThemeEnforcement.java:114)
at com.google.android.material.textfield.TextInputLayout.<init>(TextInputLayout.java:476)
at com.google.android.material.textfield.TextInputLayout.<init>(TextInputLayout.java:455)
at java.base/jdk.internal.reflect.NativeConstructorAccessorImpl.newInstance0(Native Method)
at java.base/jdk.internal.reflect.NativeConstructorAccessorImpl.newInstance(NativeConstructorAccessorImpl.java:77)
at java.base/jdk.internal.reflect.DelegatingConstructorAccessorImpl.newInstance(DelegatingConstructorAccessorImpl.java:45)
at java.base/java.lang.reflect.Constructor.newInstanceWithCaller(Constructor.java:499)
at java.base/java.lang.reflect.Constructor.newInstance(Constructor.java:480)
at org.jetbrains.android.uipreview.ViewLoader.createNewInstance(ViewLoader.java:293)
at org.jetbrains.android.uipreview.ViewLoader.loadClass(ViewLoader.java:156)
at org.jetbrains.android.uipreview.ViewLoader.loadView(ViewLoader.java:117)
at com.android.tools.idea.rendering.LayoutlibCallbackImpl.loadView(LayoutlibCallbackImpl.java:270)
at android.view.BridgeInflater.loadCustomView(BridgeInflater.java:426)
at android.view.BridgeInflater.loadCustomView(BridgeInflater.java:437)
at android.view.BridgeInflater.createViewFromTag(BridgeInflater.java:341)
at android.view.LayoutInflater.createViewFromTag(LayoutInflater.java:965)
at android.view.LayoutInflater.rInflate_Original(LayoutInflater.java:1127)
at android.view.LayoutInflater_Delegate.rInflate(LayoutInflater_Delegate.java:72)
at android.view.LayoutInflater.rInflate(LayoutInflater.java:1101)
at android.view.LayoutInflater.rInflateChildren(LayoutInflater.java:1088)
at android.view.LayoutInflater.inflate(LayoutInflater.java:686)
at android.view.LayoutInflater.inflate(LayoutInflater.java:505)
at com.android.layoutlib.bridge.impl.RenderSessionImpl.inflate(RenderSessionImpl.java:358)
at com.android.layoutlib.bridge.Bridge.createSession(Bridge.java:450)
at com.android.tools.idea.layoutlib.LayoutLibrary.createSession(LayoutLibrary.java:122)
at com.android.tools.idea.rendering.RenderTask.createRenderSession(RenderTask.java:701)
at com.android.tools.idea.rendering.RenderTask.lambda$inflate$8(RenderTask.java:848)
at com.android.tools.idea.rendering.RenderExecutor$runAsyncActionWithTimeout$3.run(RenderExecutor.kt:200)
at com.android.tools.idea.rendering.RenderExecutor$PriorityRunnable.run(RenderExecutor.kt:298)
at java.base/java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1136)
at java.base/java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:635)
at java.base/java.lang.Thread.run(Thread.java:833)

错误核心原因：当前App主题不是Theme.MaterialComponents（或其子类），而你使用的OutlinedBox.ExposedDropdownMenu样式要求必须基于Material Components主题。

有两种解决方式：

方式一：全局修改App主题 #

找到项目中的res/values/styles.xml（或res/values/themes.xml，依项目结构而定），将App主题的父类改为Material Components系列主题，示例：

<style name="AppTheme" parent="Theme.MaterialComponents.DayNight.DarkActionBar">
    <!-- 保留已有的其他主题配置 -->
</style>

也可根据需求选择Theme.MaterialComponents.Light.NoActionBar等其他Material主题。

方式二：单独给TextInputLayout指定主题 #

若不想修改全局主题，可直接在布局的TextInputLayout标签中添加android:theme属性指定Material主题，示例：

<com.google.android.material.textfield.TextInputLayout
    android:layout_width="match_parent"
    android:layout_height="wrap_content"
    style="@style/Widget.MaterialComponents.TextInputLayout.OutlinedBox.ExposedDropdownMenu"
    android:theme="@style/Theme.MaterialComponents.DayNight">

    <!-- 放置AutoCompleteTextView等子视图 -->
</com.google.android.material.textfield.TextInputLayout>

最后操作 #

修改完成后，点击IDE顶部「Build Project」按钮，再刷新布局预览窗口（点击预览窗口的刷新图标），错误即可解决。

内容的提问来源于stack exchange，提问作者Kelvin