“无法访问主线程上的数据库，因为它可能会长时间锁定UI."我的协程错误 [英] "Cannot access database on the main thread since it may potentially lock the UI for a long period of time." error on my Coroutine

问题描述

我的协程正在主线程上运行，这是我在我的协程上下文中指定的:

My Coroutine is running on the main thread, which i've specified in my Coroutine context:

class ClickPreference(context: Context, attrs: AttributeSet) : Preference(context, attrs), CoroutineScope, View.OnClickListener {

    override val coroutineContext: CoroutineContext
        get() = Dispatchers.Main

override fun onClick(v: View?) {
    when (key){
        "logout" -> {
            CoroutineScope(coroutineContext).launch {
                CustomApplication.database?.clearAllTables()
                Log.d("MapFragment", "Cleared Tables")
            }
            if (Profile.getCurrentProfile() != null) LoginManager.getInstance().logOut()
            FirebaseAuth.getInstance().signOut()
            val intent = Intent(context, MainActivity::class.java)
            context.startActivity(intent)
        }
    }
}

但是我仍然收到此错误:

But I'm still getting this error:

java.lang.IllegalStateException: Cannot access database on the main thread since it may potentially lock the UI for a long period of time.

在我上面的协程调用CustomApplication.database?.clearAllTables()到我的Room数据库.

on my above Coroutine call CustomApplication.database?.clearAllTables() to my Room database.

这是我的CustomApplication:

class CustomApplication : Application() {

    companion object {
        var database: AppDatabase? = null
    }

    override fun onCreate() {
        super.onCreate()
        CustomApplication.database = Room.databaseBuilder(this, AppDatabase::class.java, "AppDatabase").build()
    }

如果我的协程上下文在主线程上运行，为什么仍会出现错误?

Why am I still getting the error if my coroutine context runs on the main thread?

推荐答案

该错误表明该代码不应在主线程上运行.数据库操作(以及其他所有形式的IO)可能会花费很长时间，应该在后台运行.

The error says that it should NOT run on the main thread. Database operations (and every other form of IO) can take a long time and should be run in the background.

您应该使用专门用于运行IO操作的Dispatchers.IO.

You should use Dispatchers.IO which is designed for running IO operations.

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