优化

app/src/main/java/io/legado/app/ui/main/MainActivity.kt

@@ -24,8 +24,9 @@ import io.legado.app.ui.main.myconfig.MyConfigFragment
 import io.legado.app.utils.getCompatColor
 import io.legado.app.utils.getViewModel
 import kotlinx.android.synthetic.main.activity_main.*
-import kotlinx.coroutines.Dispatchers.Main
+import kotlinx.coroutines.Dispatchers.IO
 import kotlinx.coroutines.launch
+import kotlinx.coroutines.withContext
 
 class MainActivity : BaseActivity<MainViewModel>(), BottomNavigationView.OnNavigationItemSelectedListener,
     ViewPager.OnPageChangeListener {
@@ -62,8 +63,7 @@ class MainActivity : BaseActivity<MainViewModel>(), BottomNavigationView.OnNavig
 
     private fun importYueDu() {
         launch {
-            if (App.db.bookDao().allBookCount == 0) {
-                launch(Main) {
+            if (withContext(IO) { App.db.bookDao().allBookCount == 0 }) {
                 PermissionsCompat.Builder(this@MainActivity)
                     .addPermissions(*Permissions.Group.STORAGE)
                     .rationale(R.string.tip_perm_request_storage)
@@ -72,7 +72,6 @@ class MainActivity : BaseActivity<MainViewModel>(), BottomNavigationView.OnNavig
             }
         }
     }
-    }
 
     override fun onPageScrollStateChanged(state: Int) {