为什么在更新AndroidStudio后显示错误类型不匹配？

代码A在我的旧版本中运行良好，现在我将Android Studio更新到3.4.2，并把buildToolsVersion“ 29.0.1”更新了，并且使用了最新的androidx。

但是我收到错误Type不匹配，您可以看到图1，我该如何解决？谢谢！

图片1

代码A

class PreferenceTool(private val context: Context, private val name: String,  private val default: T) {

    private val prefs: SharedPreferences by lazy {       
        context.defaultSharedPreferences        
    }

    operator fun getValue(thisRef: Any?, property: KProperty<*>): T = findPreference(name, default)

    operator fun setValue(thisRef: Any?, property: KProperty<*>, value: T) {
        putPreference(name, value)
    }

    @Suppress("UNCHECKED_CAST")
    private fun findPreference(name: String, default: T): T = with(prefs) {
        val res: Any = when (default) {
            is Long -> getLong(name, default)
            is String -> getString(name, default)
            is Int -> getInt(name, default)
            is Boolean -> getBoolean(name, default)
            is Float -> getFloat(name, default)
            else -> throw IllegalArgumentException("This type can be saved into Preferences")
        }
        res as T
    }

    @SuppressLint("CommitPrefEdits")
    private fun putPreference(name: String, value: T) = with(prefs.edit()) {
        when (value) {
            is Long -> putLong(name, value)
            is String -> putString(name, value)
            is Int -> putInt(name, value)
            is Boolean -> putBoolean(name, value)
            is Float -> putFloat(name, value)
            else -> throw IllegalArgumentException("This type can't be saved into Preferences")
        }.apply()
    }
}

新增内容1

而且，我发现代码B和代码C都可以正确编译。我不知道为什么 似乎is String -> getString(name, default)导致错误。

代码B

@Suppress("UNCHECKED_CAST")
private fun findPreference(name: String, default: T): T = with(prefs) {
    val res: Any = when (default) {
        is Long -> getLong(name, default)
        else -> throw IllegalArgumentException("This type can be saved into Preferences")
    }
    res as T
}

代码C

@Suppress("UNCHECKED_CAST")
private fun findPreference(name: String, default: T): T = with(prefs) {
    val res: Any = when (default) {
        is Long -> getLong(name, default)
        is Int -> getInt(name, default)
        is Boolean -> getBoolean(name, default)
        is Float -> getFloat(name, default)
        else -> throw IllegalArgumentException("This type can be saved into Preferences")
    }
    res as T
}

新增内容2

似乎由图像2prefs.getString(name, default)返回。我不知道是否有Build 29.0.1的错误吗？String?

@RecentlyNullable
String getString(String var1, @RecentlyNullable String var2);

@Nullable
String getString(String var1, @Nullable String var2);