diff --git a/app/src/main/java/io/legado/app/ui/association/FileAssociationActivity.kt b/app/src/main/java/io/legado/app/ui/association/FileAssociationActivity.kt
index bfd63c362..6c5741414 100644
--- a/app/src/main/java/io/legado/app/ui/association/FileAssociationActivity.kt
+++ b/app/src/main/java/io/legado/app/ui/association/FileAssociationActivity.kt
@@ -2,7 +2,6 @@ package io.legado.app.ui.association
 
 import android.content.Intent
 import android.os.Bundle
-import androidx.lifecycle.Observer
 import io.legado.app.R
 import io.legado.app.base.VMBaseActivity
 import io.legado.app.constant.Theme
@@ -23,12 +22,12 @@ class FileAssociationActivity : VMBaseActivity<FileAssociationViewModel>(
 
     override fun onActivityCreated(savedInstanceState: Bundle?) {
         rotate_loading.show()
-        viewModel.errorLiveData.observe(this, Observer {
+        viewModel.errorLiveData.observe(this, {
             rotate_loading.hide()
             toast(it)
             finish()
         })
-        viewModel.successLiveData.observe(this, Observer {
+        viewModel.successLiveData.observe(this, {
             rotate_loading.hide()
             startActivity(it)
             finish()
diff --git a/app/src/main/java/io/legado/app/ui/association/ImportBookSourceActivity.kt b/app/src/main/java/io/legado/app/ui/association/ImportBookSourceActivity.kt
index 874bb9e5e..0b74690f2 100644
--- a/app/src/main/java/io/legado/app/ui/association/ImportBookSourceActivity.kt
+++ b/app/src/main/java/io/legado/app/ui/association/ImportBookSourceActivity.kt
@@ -9,7 +9,6 @@ import android.view.MenuItem
 import android.view.View
 import android.view.ViewGroup
 import androidx.appcompat.widget.Toolbar
-import androidx.lifecycle.Observer
 import androidx.recyclerview.widget.LinearLayoutManager
 import io.legado.app.R
 import io.legado.app.base.BaseDialogFragment
@@ -41,11 +40,11 @@ class ImportBookSourceActivity : VMBaseActivity<ImportBookSourceViewModel>(
 
     override fun onActivityCreated(savedInstanceState: Bundle?) {
         rotate_loading.show()
-        viewModel.errorLiveData.observe(this, Observer {
+        viewModel.errorLiveData.observe(this, {
             rotate_loading.hide()
             errorDialog(it)
         })
-        viewModel.successLiveData.observe(this, Observer {
+        viewModel.successLiveData.observe(this, {
             rotate_loading.hide()
             if (it > 0) {
                 successDialog()
diff --git a/app/src/main/java/io/legado/app/ui/association/ImportReplaceRuleActivity.kt b/app/src/main/java/io/legado/app/ui/association/ImportReplaceRuleActivity.kt
index c5d757597..12ae447d1 100644
--- a/app/src/main/java/io/legado/app/ui/association/ImportReplaceRuleActivity.kt
+++ b/app/src/main/java/io/legado/app/ui/association/ImportReplaceRuleActivity.kt
@@ -1,7 +1,6 @@
 package io.legado.app.ui.association
 
 import android.os.Bundle
-import androidx.lifecycle.Observer
 import io.legado.app.App
 import io.legado.app.R
 import io.legado.app.base.VMBaseActivity
@@ -26,11 +25,11 @@ class ImportReplaceRuleActivity : VMBaseActivity<ImportReplaceRuleViewModel>(
 
     override fun onActivityCreated(savedInstanceState: Bundle?) {
         rotate_loading.show()
-        viewModel.errorLiveData.observe(this, Observer {
+        viewModel.errorLiveData.observe(this, {
             rotate_loading.hide()
             errorDialog(it)
         })
-        viewModel.successLiveData.observe(this, Observer {
+        viewModel.successLiveData.observe(this, {
             rotate_loading.hide()
             if (it.size > 0) {
                 successDialog(it)
diff --git a/app/src/main/java/io/legado/app/ui/association/ImportRssSourceActivity.kt b/app/src/main/java/io/legado/app/ui/association/ImportRssSourceActivity.kt
index 35e3ca284..8862f2dbe 100644
--- a/app/src/main/java/io/legado/app/ui/association/ImportRssSourceActivity.kt
+++ b/app/src/main/java/io/legado/app/ui/association/ImportRssSourceActivity.kt
@@ -9,7 +9,6 @@ import android.view.MenuItem
 import android.view.View
 import android.view.ViewGroup
 import androidx.appcompat.widget.Toolbar
-import androidx.lifecycle.Observer
 import androidx.recyclerview.widget.LinearLayoutManager
 import io.legado.app.R
 import io.legado.app.base.BaseDialogFragment
@@ -41,11 +40,11 @@ class ImportRssSourceActivity : VMBaseActivity<ImportRssSourceViewModel>(
 
     override fun onActivityCreated(savedInstanceState: Bundle?) {
         rotate_loading.show()
-        viewModel.errorLiveData.observe(this, Observer {
+        viewModel.errorLiveData.observe(this, {
             rotate_loading.hide()
             errorDialog(it)
         })
-        viewModel.successLiveData.observe(this, Observer {
+        viewModel.successLiveData.observe(this, {
             rotate_loading.hide()
             if (it > 0) {
                 successDialog()
diff --git a/app/src/main/java/io/legado/app/ui/audio/AudioPlayActivity.kt b/app/src/main/java/io/legado/app/ui/audio/AudioPlayActivity.kt
index 9ed2b173d..f1d2883fb 100644
--- a/app/src/main/java/io/legado/app/ui/audio/AudioPlayActivity.kt
+++ b/app/src/main/java/io/legado/app/ui/audio/AudioPlayActivity.kt
@@ -8,7 +8,6 @@ import android.os.Bundle
 import android.view.Menu
 import android.view.MenuItem
 import android.widget.SeekBar
-import androidx.lifecycle.Observer
 import com.bumptech.glide.RequestBuilder
 import com.bumptech.glide.load.resource.drawable.DrawableTransitionOptions
 import com.bumptech.glide.request.RequestOptions.bitmapTransform
@@ -48,8 +47,8 @@ class AudioPlayActivity :
 
     override fun onActivityCreated(savedInstanceState: Bundle?) {
         title_bar.transparent()
-        AudioPlay.titleData.observe(this, Observer { title_bar.title = it })
-        AudioPlay.coverData.observe(this, Observer { upCover(it) })
+        AudioPlay.titleData.observe(this, { title_bar.title = it })
+        AudioPlay.coverData.observe(this, { upCover(it) })
         viewModel.initData(intent)
         initView()
     }
diff --git a/app/src/main/java/io/legado/app/ui/book/arrange/ArrangeBookActivity.kt b/app/src/main/java/io/legado/app/ui/book/arrange/ArrangeBookActivity.kt
index 491922cb1..ab37c5fe1 100644
--- a/app/src/main/java/io/legado/app/ui/book/arrange/ArrangeBookActivity.kt
+++ b/app/src/main/java/io/legado/app/ui/book/arrange/ArrangeBookActivity.kt
@@ -5,7 +5,6 @@ import android.view.Menu
 import android.view.MenuItem
 import androidx.appcompat.widget.PopupMenu
 import androidx.lifecycle.LiveData
-import androidx.lifecycle.Observer
 import androidx.recyclerview.widget.ItemTouchHelper
 import androidx.recyclerview.widget.LinearLayoutManager
 import io.legado.app.App
@@ -94,7 +93,7 @@ class ArrangeBookActivity : VMBaseActivity<ArrangeBookViewModel>(R.layout.activi
     private fun initGroupData() {
         groupLiveData?.removeObservers(this)
         groupLiveData = App.db.bookGroupDao().liveDataAll()
-        groupLiveData?.observe(this, Observer {
+        groupLiveData?.observe(this, {
             groupList.clear()
             groupList.addAll(it)
             adapter.notifyDataSetChanged()
@@ -112,7 +111,7 @@ class ArrangeBookActivity : VMBaseActivity<ArrangeBookViewModel>(R.layout.activi
                 AppConst.bookGroupNone.groupId -> App.db.bookDao().observeNoGroup()
                 else -> App.db.bookDao().observeByGroup(groupId)
             }
-        booksLiveData?.observe(this, Observer { list ->
+        booksLiveData?.observe(this, { list ->
             val books = when (getPrefInt(PreferKey.bookshelfSort)) {
                 1 -> list.sortedByDescending { it.latestChapterTime }
                 2 -> list.sortedBy { it.name }
diff --git a/app/src/main/java/io/legado/app/ui/book/changecover/ChangeCoverDialog.kt b/app/src/main/java/io/legado/app/ui/book/changecover/ChangeCoverDialog.kt
index 2539e6dc9..4a898fed4 100644
--- a/app/src/main/java/io/legado/app/ui/book/changecover/ChangeCoverDialog.kt
+++ b/app/src/main/java/io/legado/app/ui/book/changecover/ChangeCoverDialog.kt
@@ -8,7 +8,6 @@ import android.view.View
 import android.view.ViewGroup
 import androidx.appcompat.widget.Toolbar
 import androidx.fragment.app.FragmentManager
-import androidx.lifecycle.Observer
 import androidx.recyclerview.widget.DiffUtil
 import androidx.recyclerview.widget.GridLayoutManager
 import io.legado.app.R
@@ -83,7 +82,7 @@ class ChangeCoverDialog : BaseDialogFragment(),
 
     override fun observeLiveBus() {
         super.observeLiveBus()
-        viewModel.searchStateData.observe(viewLifecycleOwner, Observer {
+        viewModel.searchStateData.observe(viewLifecycleOwner, {
             refresh_progress_bar.isAutoLoading = it
             if (it) {
                 stopMenuItem?.setIcon(R.drawable.ic_stop_black_24dp)
@@ -92,7 +91,7 @@ class ChangeCoverDialog : BaseDialogFragment(),
             }
             tool_bar.menu.applyTint(requireContext(), Theme.getTheme())
         })
-        viewModel.searchBooksLiveData.observe(viewLifecycleOwner, Observer {
+        viewModel.searchBooksLiveData.observe(viewLifecycleOwner, {
             val diffResult = DiffUtil.calculateDiff(DiffCallBack(adapter.getItems(), it))
             adapter.setItems(it)
             diffResult.dispatchUpdatesTo(adapter)
diff --git a/app/src/main/java/io/legado/app/ui/book/changesource/ChangeSourceDialog.kt b/app/src/main/java/io/legado/app/ui/book/changesource/ChangeSourceDialog.kt
index d27f8b756..7ebb4c0db 100644
--- a/app/src/main/java/io/legado/app/ui/book/changesource/ChangeSourceDialog.kt
+++ b/app/src/main/java/io/legado/app/ui/book/changesource/ChangeSourceDialog.kt
@@ -9,7 +9,6 @@ import android.view.ViewGroup
 import androidx.appcompat.widget.SearchView
 import androidx.appcompat.widget.Toolbar
 import androidx.fragment.app.FragmentManager
-import androidx.lifecycle.Observer
 import androidx.recyclerview.widget.DiffUtil
 import androidx.recyclerview.widget.LinearLayoutManager
 import androidx.recyclerview.widget.RecyclerView
@@ -135,7 +134,7 @@ class ChangeSourceDialog : BaseDialogFragment(),
     }
 
     private fun initLiveData() {
-        viewModel.searchStateData.observe(viewLifecycleOwner, Observer {
+        viewModel.searchStateData.observe(viewLifecycleOwner, {
             refresh_progress_bar.isAutoLoading = it
             if (it) {
                 stopMenuItem?.setIcon(R.drawable.ic_stop_black_24dp)
@@ -144,7 +143,7 @@ class ChangeSourceDialog : BaseDialogFragment(),
             }
             tool_bar.menu.applyTint(requireContext())
         })
-        viewModel.searchBooksLiveData.observe(viewLifecycleOwner, Observer {
+        viewModel.searchBooksLiveData.observe(viewLifecycleOwner, {
             val diffResult = DiffUtil.calculateDiff(DiffCallBack(adapter.getItems(), it))
             adapter.setItems(it)
             diffResult.dispatchUpdatesTo(adapter)
diff --git a/app/src/main/java/io/legado/app/ui/book/chapterlist/BookmarkFragment.kt b/app/src/main/java/io/legado/app/ui/book/chapterlist/BookmarkFragment.kt
index ef47cd2c0..b24d438e8 100644
--- a/app/src/main/java/io/legado/app/ui/book/chapterlist/BookmarkFragment.kt
+++ b/app/src/main/java/io/legado/app/ui/book/chapterlist/BookmarkFragment.kt
@@ -8,7 +8,6 @@ import android.os.Bundle
 import android.view.View
 import android.widget.EditText
 import androidx.lifecycle.LiveData
-import androidx.lifecycle.Observer
 import androidx.paging.LivePagedListBuilder
 import androidx.paging.PagedList
 import androidx.recyclerview.widget.LinearLayoutManager
@@ -59,7 +58,7 @@ class BookmarkFragment : VMBaseFragment<ChapterListViewModel>(R.layout.fragment_
                 LivePagedListBuilder(
                     App.db.bookmarkDao().observeByBook(book.bookUrl, book.name, book.author), 20
                 ).build()
-            bookmarkLiveData?.observe(viewLifecycleOwner, Observer { adapter.submitList(it) })
+            bookmarkLiveData?.observe(viewLifecycleOwner, { adapter.submitList(it) })
         }
     }
 
@@ -74,7 +73,7 @@ class BookmarkFragment : VMBaseFragment<ChapterListViewModel>(R.layout.fragment_
                     newText
                 ), 20
             ).build()
-            bookmarkLiveData?.observe(viewLifecycleOwner, Observer { adapter.submitList(it) })
+            bookmarkLiveData?.observe(viewLifecycleOwner, { adapter.submitList(it) })
         }
     }
 
diff --git a/app/src/main/java/io/legado/app/ui/book/chapterlist/ChapterListFragment.kt b/app/src/main/java/io/legado/app/ui/book/chapterlist/ChapterListFragment.kt
index 677d623e2..58d47efeb 100644
--- a/app/src/main/java/io/legado/app/ui/book/chapterlist/ChapterListFragment.kt
+++ b/app/src/main/java/io/legado/app/ui/book/chapterlist/ChapterListFragment.kt
@@ -6,7 +6,6 @@ import android.content.Intent
 import android.os.Bundle
 import android.view.View
 import androidx.lifecycle.LiveData
-import androidx.lifecycle.Observer
 import io.legado.app.App
 import io.legado.app.R
 import io.legado.app.base.VMBaseFragment
@@ -89,7 +88,7 @@ class ChapterListFragment : VMBaseFragment<ChapterListViewModel>(R.layout.fragme
     private fun initDoc() {
         tocLiveData?.removeObservers(this@ChapterListFragment)
         tocLiveData = App.db.bookChapterDao().observeByBook(viewModel.bookUrl)
-        tocLiveData?.observe(viewLifecycleOwner, Observer {
+        tocLiveData?.observe(viewLifecycleOwner, {
             adapter.setItems(it)
             if (!scrollToDurChapter) {
                 mLayoutManager.scrollToPositionWithOffset(durChapterIndex, 0)
@@ -124,7 +123,7 @@ class ChapterListFragment : VMBaseFragment<ChapterListViewModel>(R.layout.fragme
         } else {
             tocLiveData?.removeObservers(this)
             tocLiveData = App.db.bookChapterDao().liveDataSearch(viewModel.bookUrl, newText)
-            tocLiveData?.observe(viewLifecycleOwner, Observer {
+            tocLiveData?.observe(viewLifecycleOwner, {
                 adapter.setItems(it)
             })
         }
diff --git a/app/src/main/java/io/legado/app/ui/book/download/DownloadActivity.kt b/app/src/main/java/io/legado/app/ui/book/download/DownloadActivity.kt
index ecb9c6b67..d4c629381 100644
--- a/app/src/main/java/io/legado/app/ui/book/download/DownloadActivity.kt
+++ b/app/src/main/java/io/legado/app/ui/book/download/DownloadActivity.kt
@@ -6,7 +6,6 @@ import android.os.Bundle
 import android.view.Menu
 import android.view.MenuItem
 import androidx.lifecycle.LiveData
-import androidx.lifecycle.Observer
 import androidx.recyclerview.widget.LinearLayoutManager
 import com.google.android.material.snackbar.Snackbar
 import io.legado.app.App
@@ -129,7 +128,7 @@ class DownloadActivity : VMBaseActivity<DownloadViewModel>(R.layout.activity_dow
             AppConst.bookGroupNone.groupId -> App.db.bookDao().observeNoGroup()
             else -> App.db.bookDao().observeByGroup(groupId)
         }
-        booksLiveData?.observe(this, Observer { list ->
+        booksLiveData?.observe(this, { list ->
             val booksDownload = list.filter {
                 it.isOnLineTxt()
             }
@@ -147,7 +146,7 @@ class DownloadActivity : VMBaseActivity<DownloadViewModel>(R.layout.activity_dow
     private fun initGroupData() {
         groupLiveData?.removeObservers(this)
         groupLiveData = App.db.bookGroupDao().liveDataAll()
-        groupLiveData?.observe(this, Observer {
+        groupLiveData?.observe(this, {
             groupList.clear()
             groupList.addAll(it)
             adapter.notifyDataSetChanged()
diff --git a/app/src/main/java/io/legado/app/ui/book/explore/ExploreShowActivity.kt b/app/src/main/java/io/legado/app/ui/book/explore/ExploreShowActivity.kt
index dbba6b63e..a447bb9e1 100644
--- a/app/src/main/java/io/legado/app/ui/book/explore/ExploreShowActivity.kt
+++ b/app/src/main/java/io/legado/app/ui/book/explore/ExploreShowActivity.kt
@@ -1,7 +1,6 @@
 package io.legado.app.ui.book.explore
 
 import android.os.Bundle
-import androidx.lifecycle.Observer
 import androidx.recyclerview.widget.LinearLayoutManager
 import androidx.recyclerview.widget.RecyclerView
 import io.legado.app.R
@@ -27,7 +26,7 @@ class ExploreShowActivity : VMBaseActivity<ExploreShowViewModel>(R.layout.activi
     override fun onActivityCreated(savedInstanceState: Bundle?) {
         title_bar.title = intent.getStringExtra("exploreName")
         initRecyclerView()
-        viewModel.booksData.observe(this, Observer { upData(it) })
+        viewModel.booksData.observe(this, { upData(it) })
         viewModel.initData(intent)
     }
 
diff --git a/app/src/main/java/io/legado/app/ui/book/group/GroupManageDialog.kt b/app/src/main/java/io/legado/app/ui/book/group/GroupManageDialog.kt
index 73bdd8595..d5efe8126 100644
--- a/app/src/main/java/io/legado/app/ui/book/group/GroupManageDialog.kt
+++ b/app/src/main/java/io/legado/app/ui/book/group/GroupManageDialog.kt
@@ -10,7 +10,6 @@ import android.view.View
 import android.view.ViewGroup
 import android.widget.EditText
 import androidx.appcompat.widget.Toolbar
-import androidx.lifecycle.Observer
 import androidx.recyclerview.widget.DiffUtil
 import androidx.recyclerview.widget.ItemTouchHelper
 import androidx.recyclerview.widget.LinearLayoutManager
@@ -78,7 +77,7 @@ class GroupManageDialog : BaseDialogFragment(), Toolbar.OnMenuItemClickListener
         tv_ok.setTextColor(requireContext().accentColor)
         tv_ok.visible()
         tv_ok.onClick { dismiss() }
-        App.db.bookGroupDao().liveDataAll().observe(viewLifecycleOwner, Observer {
+        App.db.bookGroupDao().liveDataAll().observe(viewLifecycleOwner, {
             val diffResult =
                 DiffUtil.calculateDiff(GroupDiffCallBack(ArrayList(adapter.getItems()), it))
             adapter.setItems(it, diffResult)
diff --git a/app/src/main/java/io/legado/app/ui/book/group/GroupSelectDialog.kt b/app/src/main/java/io/legado/app/ui/book/group/GroupSelectDialog.kt
index df058b901..7a83ab140 100644
--- a/app/src/main/java/io/legado/app/ui/book/group/GroupSelectDialog.kt
+++ b/app/src/main/java/io/legado/app/ui/book/group/GroupSelectDialog.kt
@@ -11,7 +11,6 @@ import android.view.ViewGroup
 import android.widget.EditText
 import androidx.appcompat.widget.Toolbar
 import androidx.fragment.app.FragmentManager
-import androidx.lifecycle.Observer
 import androidx.recyclerview.widget.ItemTouchHelper
 import androidx.recyclerview.widget.LinearLayoutManager
 import androidx.recyclerview.widget.RecyclerView
@@ -113,7 +112,7 @@ class GroupSelectDialog : BaseDialogFragment(), Toolbar.OnMenuItemClickListener
     }
 
     private fun initData() {
-        App.db.bookGroupDao().liveDataAll().observe(viewLifecycleOwner, Observer {
+        App.db.bookGroupDao().liveDataAll().observe(viewLifecycleOwner, {
             adapter.setItems(it)
         })
     }
diff --git a/app/src/main/java/io/legado/app/ui/book/info/BookInfoActivity.kt b/app/src/main/java/io/legado/app/ui/book/info/BookInfoActivity.kt
index 906cacaf7..2591a30c4 100644
--- a/app/src/main/java/io/legado/app/ui/book/info/BookInfoActivity.kt
+++ b/app/src/main/java/io/legado/app/ui/book/info/BookInfoActivity.kt
@@ -9,7 +9,6 @@ import android.view.Menu
 import android.view.MenuItem
 import android.widget.CheckBox
 import android.widget.LinearLayout
-import androidx.lifecycle.Observer
 import com.bumptech.glide.RequestBuilder
 import com.bumptech.glide.load.resource.drawable.DrawableTransitionOptions
 import com.bumptech.glide.request.RequestOptions.bitmapTransform
@@ -66,8 +65,8 @@ class BookInfoActivity :
         scroll_view.setBackgroundColor(backgroundColor)
         fl_action.setBackgroundColor(bottomBackground)
         tv_shelf.setTextColor(getPrimaryTextColor(ColorUtils.isColorLight(bottomBackground)))
-        viewModel.bookData.observe(this, Observer { showBook(it) })
-        viewModel.chapterListData.observe(this, Observer { upLoading(false, it) })
+        viewModel.bookData.observe(this, { showBook(it) })
+        viewModel.chapterListData.observe(this, { upLoading(false, it) })
         viewModel.initData(intent)
         initOnClick()
     }
diff --git a/app/src/main/java/io/legado/app/ui/book/info/edit/BookInfoEditActivity.kt b/app/src/main/java/io/legado/app/ui/book/info/edit/BookInfoEditActivity.kt
index ce8fe76fc..3e4986bde 100644
--- a/app/src/main/java/io/legado/app/ui/book/info/edit/BookInfoEditActivity.kt
+++ b/app/src/main/java/io/legado/app/ui/book/info/edit/BookInfoEditActivity.kt
@@ -7,7 +7,6 @@ import android.os.Bundle
 import android.view.Menu
 import android.view.MenuItem
 import androidx.documentfile.provider.DocumentFile
-import androidx.lifecycle.Observer
 import io.legado.app.R
 import io.legado.app.base.VMBaseActivity
 import io.legado.app.data.entities.Book
@@ -30,7 +29,7 @@ class BookInfoEditActivity :
         get() = getViewModel(BookInfoEditViewModel::class.java)
 
     override fun onActivityCreated(savedInstanceState: Bundle?) {
-        viewModel.bookData.observe(this, Observer { upView(it) })
+        viewModel.bookData.observe(this, { upView(it) })
         if (viewModel.bookData.value == null) {
             intent.getStringExtra("bookUrl")?.let {
                 viewModel.loadBook(it)
diff --git a/app/src/main/java/io/legado/app/ui/book/local/ImportBookActivity.kt b/app/src/main/java/io/legado/app/ui/book/local/ImportBookActivity.kt
index 994b7d8ca..86c5e5ecd 100644
--- a/app/src/main/java/io/legado/app/ui/book/local/ImportBookActivity.kt
+++ b/app/src/main/java/io/legado/app/ui/book/local/ImportBookActivity.kt
@@ -12,7 +12,6 @@ import android.view.View
 import androidx.appcompat.widget.PopupMenu
 import androidx.documentfile.provider.DocumentFile
 import androidx.lifecycle.LiveData
-import androidx.lifecycle.Observer
 import androidx.recyclerview.widget.LinearLayoutManager
 import io.legado.app.App
 import io.legado.app.R
@@ -114,7 +113,7 @@ class ImportBookActivity : VMBaseActivity<ImportBookViewModel>(R.layout.activity
     private fun initData() {
         localUriLiveData?.removeObservers(this)
         localUriLiveData = App.db.bookDao().observeLocalUri()
-        localUriLiveData?.observe(this, Observer {
+        localUriLiveData?.observe(this, {
             adapter.upBookHas(it)
         })
     }
diff --git a/app/src/main/java/io/legado/app/ui/book/read/config/TocRegexDialog.kt b/app/src/main/java/io/legado/app/ui/book/read/config/TocRegexDialog.kt
index 22ae62c18..4603a0d33 100644
--- a/app/src/main/java/io/legado/app/ui/book/read/config/TocRegexDialog.kt
+++ b/app/src/main/java/io/legado/app/ui/book/read/config/TocRegexDialog.kt
@@ -11,7 +11,6 @@ import android.view.ViewGroup
 import androidx.appcompat.widget.Toolbar
 import androidx.fragment.app.FragmentManager
 import androidx.lifecycle.LiveData
-import androidx.lifecycle.Observer
 import androidx.recyclerview.widget.ItemTouchHelper
 import androidx.recyclerview.widget.LinearLayoutManager
 import androidx.recyclerview.widget.RecyclerView
@@ -104,7 +103,7 @@ class TocRegexDialog : BaseDialogFragment(), Toolbar.OnMenuItemClickListener {
     private fun initData() {
         tocRegexLiveData?.removeObservers(viewLifecycleOwner)
         tocRegexLiveData = App.db.txtTocRule().observeAll()
-        tocRegexLiveData?.observe(viewLifecycleOwner, Observer { tocRules ->
+        tocRegexLiveData?.observe(viewLifecycleOwner, { tocRules ->
             initSelectedName(tocRules)
             adapter.setItems(tocRules)
         })
diff --git a/app/src/main/java/io/legado/app/ui/book/search/SearchActivity.kt b/app/src/main/java/io/legado/app/ui/book/search/SearchActivity.kt
index acf63099b..681e9aa9e 100644
--- a/app/src/main/java/io/legado/app/ui/book/search/SearchActivity.kt
+++ b/app/src/main/java/io/legado/app/ui/book/search/SearchActivity.kt
@@ -7,7 +7,6 @@ import android.view.View.GONE
 import android.view.View.VISIBLE
 import androidx.appcompat.widget.SearchView
 import androidx.lifecycle.LiveData
-import androidx.lifecycle.Observer
 import androidx.recyclerview.widget.LinearLayoutManager
 import androidx.recyclerview.widget.RecyclerView
 import com.google.android.flexbox.FlexboxLayoutManager
@@ -176,17 +175,17 @@ class SearchActivity : VMBaseActivity<SearchViewModel>(R.layout.activity_book_se
     }
 
     private fun initLiveData() {
-        App.db.bookSourceDao().liveGroupEnabled().observe(this, Observer {
+        App.db.bookSourceDao().liveGroupEnabled().observe(this, {
             groups.clear()
             it.map { group ->
                 groups.addAll(group.splitNotBlank(",", ";"))
             }
             upGroupMenu()
         })
-        viewModel.searchBookLiveData.observe(this, Observer {
+        viewModel.searchBookLiveData.observe(this, {
             upSearchItems(it)
         })
-        viewModel.isSearchLiveData.observe(this, Observer {
+        viewModel.isSearchLiveData.observe(this, {
             if (it) {
                 startSearch()
             } else {
@@ -254,7 +253,7 @@ class SearchActivity : VMBaseActivity<SearchViewModel>(R.layout.activity_book_se
             rv_bookshelf_search.gone()
         } else {
             bookData = App.db.bookDao().liveDataSearch(key)
-            bookData?.observe(this, Observer {
+            bookData?.observe(this, {
                 if (it.isEmpty()) {
                     tv_book_show.gone()
                     rv_bookshelf_search.gone()
@@ -272,7 +271,7 @@ class SearchActivity : VMBaseActivity<SearchViewModel>(R.layout.activity_book_se
             } else {
                 App.db.searchKeywordDao().liveDataSearch(key)
             }
-        historyData?.observe(this, Observer {
+        historyData?.observe(this, {
             historyKeyAdapter.setItems(it)
             if (it.isEmpty()) {
                 tv_clear_history.invisible()
diff --git a/app/src/main/java/io/legado/app/ui/book/source/manage/BookSourceActivity.kt b/app/src/main/java/io/legado/app/ui/book/source/manage/BookSourceActivity.kt
index da57654f4..c06110f12 100644
--- a/app/src/main/java/io/legado/app/ui/book/source/manage/BookSourceActivity.kt
+++ b/app/src/main/java/io/legado/app/ui/book/source/manage/BookSourceActivity.kt
@@ -11,7 +11,6 @@ import androidx.appcompat.widget.PopupMenu
 import androidx.appcompat.widget.SearchView
 import androidx.documentfile.provider.DocumentFile
 import androidx.lifecycle.LiveData
-import androidx.lifecycle.Observer
 import androidx.recyclerview.widget.DiffUtil
 import androidx.recyclerview.widget.ItemTouchHelper
 import androidx.recyclerview.widget.LinearLayoutManager
@@ -164,7 +163,7 @@ class BookSourceActivity : VMBaseActivity<BookSourceViewModel>(R.layout.activity
                 App.db.bookSourceDao().liveDataSearch("%$searchKey%")
             }
         }
-        bookSourceLiveDate?.observe(this, Observer { data ->
+        bookSourceLiveDate?.observe(this, { data ->
             val sourceList = when (sort) {
                 1 -> data.sortedBy { it.weight }
                 2 -> data.sortedBy { it.bookSourceName }
@@ -179,7 +178,7 @@ class BookSourceActivity : VMBaseActivity<BookSourceViewModel>(R.layout.activity
     }
 
     private fun initLiveDataGroup() {
-        App.db.bookSourceDao().liveGroup().observe(this, Observer {
+        App.db.bookSourceDao().liveGroup().observe(this, {
             groups.clear()
             it.map { group ->
                 groups.addAll(group.splitNotBlank(",", ";"))
diff --git a/app/src/main/java/io/legado/app/ui/book/source/manage/GroupManageDialog.kt b/app/src/main/java/io/legado/app/ui/book/source/manage/GroupManageDialog.kt
index b4c8f70d6..3724694d4 100644
--- a/app/src/main/java/io/legado/app/ui/book/source/manage/GroupManageDialog.kt
+++ b/app/src/main/java/io/legado/app/ui/book/source/manage/GroupManageDialog.kt
@@ -11,7 +11,6 @@ import android.view.ViewGroup
 import android.widget.EditText
 import androidx.appcompat.widget.Toolbar
 import androidx.fragment.app.DialogFragment
-import androidx.lifecycle.Observer
 import androidx.recyclerview.widget.LinearLayoutManager
 import io.legado.app.App
 import io.legado.app.R
@@ -69,7 +68,7 @@ class GroupManageDialog : DialogFragment(), Toolbar.OnMenuItemClickListener {
     }
 
     private fun initData() {
-        App.db.bookSourceDao().liveGroup().observe(viewLifecycleOwner, Observer {
+        App.db.bookSourceDao().liveGroup().observe(viewLifecycleOwner, {
             val groups = linkedSetOf<String>()
             it.map { group ->
                 groups.addAll(group.splitNotBlank(",", ";"))
diff --git a/app/src/main/java/io/legado/app/ui/main/bookshelf/books/BooksFragment.kt b/app/src/main/java/io/legado/app/ui/main/bookshelf/books/BooksFragment.kt
index f0731f1ed..c03292011 100644
--- a/app/src/main/java/io/legado/app/ui/main/bookshelf/books/BooksFragment.kt
+++ b/app/src/main/java/io/legado/app/ui/main/bookshelf/books/BooksFragment.kt
@@ -3,7 +3,6 @@ package io.legado.app.ui.main.bookshelf.books
 import android.os.Bundle
 import android.view.View
 import androidx.lifecycle.LiveData
-import androidx.lifecycle.Observer
 import androidx.recyclerview.widget.DiffUtil
 import androidx.recyclerview.widget.GridLayoutManager
 import androidx.recyclerview.widget.LinearLayoutManager
@@ -106,7 +105,7 @@ class BooksFragment : BaseFragment(R.layout.fragment_books),
             AppConst.bookGroupNone.groupId -> App.db.bookDao().observeNoGroup()
             else -> App.db.bookDao().observeByGroup(groupId)
         }
-        bookshelfLiveData?.observe(this, Observer { list ->
+        bookshelfLiveData?.observe(this, { list ->
             val books = when (getPrefInt(PreferKey.bookshelfSort)) {
                 1 -> list.sortedByDescending { it.latestChapterTime }
                 2 -> list.sortedBy { it.name }
diff --git a/app/src/main/java/io/legado/app/ui/main/rss/RssFragment.kt b/app/src/main/java/io/legado/app/ui/main/rss/RssFragment.kt
index 334ce9e64..82ccf867f 100644
--- a/app/src/main/java/io/legado/app/ui/main/rss/RssFragment.kt
+++ b/app/src/main/java/io/legado/app/ui/main/rss/RssFragment.kt
@@ -4,7 +4,6 @@ import android.os.Bundle
 import android.view.Menu
 import android.view.MenuItem
 import android.view.View
-import androidx.lifecycle.Observer
 import androidx.recyclerview.widget.GridLayoutManager
 import io.legado.app.App
 import io.legado.app.R
@@ -56,7 +55,7 @@ class RssFragment : VMBaseFragment<RssSourceViewModel>(R.layout.fragment_rss),
     }
 
     private fun initData() {
-        App.db.rssSourceDao().liveEnabled().observe(viewLifecycleOwner, Observer {
+        App.db.rssSourceDao().liveEnabled().observe(viewLifecycleOwner, {
             if (it.isEmpty()) {
                 getViewModelOfActivity(MainViewModel::class.java).initRss()
             }
diff --git a/app/src/main/java/io/legado/app/ui/replacerule/GroupManageDialog.kt b/app/src/main/java/io/legado/app/ui/replacerule/GroupManageDialog.kt
index adc0d5cbb..17d5bcd53 100644
--- a/app/src/main/java/io/legado/app/ui/replacerule/GroupManageDialog.kt
+++ b/app/src/main/java/io/legado/app/ui/replacerule/GroupManageDialog.kt
@@ -11,7 +11,6 @@ import android.view.ViewGroup
 import android.widget.EditText
 import androidx.appcompat.widget.Toolbar
 import androidx.fragment.app.DialogFragment
-import androidx.lifecycle.Observer
 import androidx.recyclerview.widget.LinearLayoutManager
 import io.legado.app.App
 import io.legado.app.R
@@ -69,7 +68,7 @@ class GroupManageDialog : DialogFragment(), Toolbar.OnMenuItemClickListener {
         recycler_view.layoutManager = LinearLayoutManager(requireContext())
         recycler_view.addItemDecoration(VerticalDivider(requireContext()))
         recycler_view.adapter = adapter
-        App.db.replaceRuleDao().liveGroup().observe(viewLifecycleOwner, Observer {
+        App.db.replaceRuleDao().liveGroup().observe(viewLifecycleOwner, {
             val groups = linkedSetOf<String>()
             it.map { group ->
                 groups.addAll(group.splitNotBlank(",", ";"))
diff --git a/app/src/main/java/io/legado/app/ui/replacerule/ReplaceRuleActivity.kt b/app/src/main/java/io/legado/app/ui/replacerule/ReplaceRuleActivity.kt
index 554bf635b..adf9fbb03 100644
--- a/app/src/main/java/io/legado/app/ui/replacerule/ReplaceRuleActivity.kt
+++ b/app/src/main/java/io/legado/app/ui/replacerule/ReplaceRuleActivity.kt
@@ -11,7 +11,6 @@ import androidx.appcompat.widget.PopupMenu
 import androidx.appcompat.widget.SearchView
 import androidx.documentfile.provider.DocumentFile
 import androidx.lifecycle.LiveData
-import androidx.lifecycle.Observer
 import androidx.recyclerview.widget.DiffUtil
 import androidx.recyclerview.widget.ItemTouchHelper
 import androidx.recyclerview.widget.LinearLayoutManager
@@ -133,7 +132,7 @@ class ReplaceRuleActivity : VMBaseActivity<ReplaceRuleViewModel>(R.layout.activi
         } else {
             App.db.replaceRuleDao().liveDataSearch(key)
         }
-        replaceRuleLiveData?.observe(this, Observer {
+        replaceRuleLiveData?.observe(this, {
             if (dataInit) {
                 setResult(Activity.RESULT_OK)
             }
@@ -146,7 +145,7 @@ class ReplaceRuleActivity : VMBaseActivity<ReplaceRuleViewModel>(R.layout.activi
     }
 
     private fun observeGroupData() {
-        App.db.replaceRuleDao().liveGroup().observe(this, Observer {
+        App.db.replaceRuleDao().liveGroup().observe(this, {
             groups.clear()
             it.map { group ->
                 groups.addAll(group.splitNotBlank(",", ";"))
diff --git a/app/src/main/java/io/legado/app/ui/replacerule/edit/ReplaceEditDialog.kt b/app/src/main/java/io/legado/app/ui/replacerule/edit/ReplaceEditDialog.kt
index 012a042a9..1ee635f56 100644
--- a/app/src/main/java/io/legado/app/ui/replacerule/edit/ReplaceEditDialog.kt
+++ b/app/src/main/java/io/legado/app/ui/replacerule/edit/ReplaceEditDialog.kt
@@ -11,7 +11,6 @@ import android.widget.EditText
 import android.widget.PopupWindow
 import androidx.appcompat.widget.Toolbar
 import androidx.fragment.app.FragmentManager
-import androidx.lifecycle.Observer
 import io.legado.app.R
 import io.legado.app.base.BaseDialogFragment
 import io.legado.app.constant.AppConst
@@ -71,7 +70,7 @@ class ReplaceEditDialog : BaseDialogFragment(),
         tool_bar.inflateMenu(R.menu.replace_edit)
         tool_bar.menu.applyTint(requireContext())
         tool_bar.setOnMenuItemClickListener(this)
-        viewModel.replaceRuleData.observe(viewLifecycleOwner, Observer {
+        viewModel.replaceRuleData.observe(viewLifecycleOwner, {
             upReplaceView(it)
         })
         arguments?.let {
diff --git a/app/src/main/java/io/legado/app/ui/rss/article/RssArticlesFragment.kt b/app/src/main/java/io/legado/app/ui/rss/article/RssArticlesFragment.kt
index f2329cb84..f9b684592 100644
--- a/app/src/main/java/io/legado/app/ui/rss/article/RssArticlesFragment.kt
+++ b/app/src/main/java/io/legado/app/ui/rss/article/RssArticlesFragment.kt
@@ -3,7 +3,6 @@ package io.legado.app.ui.rss.article
 import android.os.Bundle
 import android.view.View
 import androidx.lifecycle.LiveData
-import androidx.lifecycle.Observer
 import androidx.recyclerview.widget.GridLayoutManager
 import androidx.recyclerview.widget.LinearLayoutManager
 import androidx.recyclerview.widget.RecyclerView
@@ -87,7 +86,7 @@ class RssArticlesFragment : VMBaseFragment<RssArticlesViewModel>(R.layout.fragme
         activityViewModel.url?.let {
             rssArticlesData?.removeObservers(this)
             rssArticlesData = App.db.rssArticleDao().liveByOriginSort(it, viewModel.sortName)
-            rssArticlesData?.observe(viewLifecycleOwner, Observer { list ->
+            rssArticlesData?.observe(viewLifecycleOwner, { list ->
                 adapter.setItems(list)
             })
         }
@@ -104,7 +103,7 @@ class RssArticlesFragment : VMBaseFragment<RssArticlesViewModel>(R.layout.fragme
     }
 
     override fun observeLiveBus() {
-        viewModel.loadFinally.observe(viewLifecycleOwner, Observer {
+        viewModel.loadFinally.observe(viewLifecycleOwner, {
             refresh_recycler_view.stopLoading()
             if (it) {
                 loadMoreView.startLoad()
diff --git a/app/src/main/java/io/legado/app/ui/rss/article/RssSortActivity.kt b/app/src/main/java/io/legado/app/ui/rss/article/RssSortActivity.kt
index 41fad7292..307374f9f 100644
--- a/app/src/main/java/io/legado/app/ui/rss/article/RssSortActivity.kt
+++ b/app/src/main/java/io/legado/app/ui/rss/article/RssSortActivity.kt
@@ -8,7 +8,6 @@ import android.view.MenuItem
 import androidx.fragment.app.Fragment
 import androidx.fragment.app.FragmentManager
 import androidx.fragment.app.FragmentStatePagerAdapter
-import androidx.lifecycle.Observer
 import io.legado.app.R
 import io.legado.app.base.VMBaseActivity
 import io.legado.app.ui.rss.source.edit.RssSourceEditActivity
@@ -30,7 +29,7 @@ class RssSortActivity : VMBaseActivity<RssSortViewModel>(R.layout.activity_rss_a
         adapter = TabFragmentPageAdapter(supportFragmentManager)
         tab_layout.setupWithViewPager(view_pager)
         view_pager.adapter = adapter
-        viewModel.titleLiveData.observe(this, Observer {
+        viewModel.titleLiveData.observe(this, {
             title_bar.title = it
         })
         viewModel.initData(intent) {
@@ -85,7 +84,7 @@ class RssSortActivity : VMBaseActivity<RssSortViewModel>(R.layout.activity_rss_a
         }
     }
 
-    private inner class TabFragmentPageAdapter internal constructor(fm: FragmentManager) :
+    private inner class TabFragmentPageAdapter(fm: FragmentManager) :
         FragmentStatePagerAdapter(fm, BEHAVIOR_RESUME_ONLY_CURRENT_FRAGMENT) {
 
         override fun getItemPosition(`object`: Any): Int {
diff --git a/app/src/main/java/io/legado/app/ui/rss/favorites/RssFavoritesActivity.kt b/app/src/main/java/io/legado/app/ui/rss/favorites/RssFavoritesActivity.kt
index f50329296..09f6d1549 100644
--- a/app/src/main/java/io/legado/app/ui/rss/favorites/RssFavoritesActivity.kt
+++ b/app/src/main/java/io/legado/app/ui/rss/favorites/RssFavoritesActivity.kt
@@ -2,7 +2,6 @@ package io.legado.app.ui.rss.favorites
 
 import android.os.Bundle
 import androidx.lifecycle.LiveData
-import androidx.lifecycle.Observer
 import androidx.recyclerview.widget.LinearLayoutManager
 import io.legado.app.App
 import io.legado.app.R
@@ -37,7 +36,7 @@ class RssFavoritesActivity : BaseActivity(R.layout.activity_rss_favorites),
     private fun initData() {
         liveData?.removeObservers(this)
         liveData = App.db.rssStarDao().liveAll()
-        liveData?.observe(this, Observer {
+        liveData?.observe(this, {
             adapter.setItems(it)
         })
     }
diff --git a/app/src/main/java/io/legado/app/ui/rss/read/ReadRssActivity.kt b/app/src/main/java/io/legado/app/ui/rss/read/ReadRssActivity.kt
index e11293cc4..908afa311 100644
--- a/app/src/main/java/io/legado/app/ui/rss/read/ReadRssActivity.kt
+++ b/app/src/main/java/io/legado/app/ui/rss/read/ReadRssActivity.kt
@@ -8,7 +8,6 @@ import android.os.Bundle
 import android.view.*
 import android.webkit.*
 import androidx.core.view.size
-import androidx.lifecycle.Observer
 import io.legado.app.R
 import io.legado.app.base.VMBaseActivity
 import io.legado.app.lib.theme.DrawableUtils
@@ -155,7 +154,7 @@ class ReadRssActivity : VMBaseActivity<ReadRssViewModel>(R.layout.activity_rss_r
 
     @SuppressLint("SetJavaScriptEnabled")
     private fun initLiveData() {
-        viewModel.contentLiveData.observe(this, Observer { content ->
+        viewModel.contentLiveData.observe(this, { content ->
             viewModel.rssArticle?.let {
                 upJavaScriptEnable()
                 val url = NetworkUtils.getAbsoluteURL(it.origin, it.link)
@@ -179,7 +178,7 @@ class ReadRssActivity : VMBaseActivity<ReadRssViewModel>(R.layout.activity_rss_r
                 }
             }
         })
-        viewModel.urlLiveData.observe(this, Observer {
+        viewModel.urlLiveData.observe(this, {
             upJavaScriptEnable()
             web_view.loadUrl(it.url, it.headerMap)
         })
diff --git a/app/src/main/java/io/legado/app/ui/rss/source/manage/GroupManageDialog.kt b/app/src/main/java/io/legado/app/ui/rss/source/manage/GroupManageDialog.kt
index 5f78beeda..bfb876e0b 100644
--- a/app/src/main/java/io/legado/app/ui/rss/source/manage/GroupManageDialog.kt
+++ b/app/src/main/java/io/legado/app/ui/rss/source/manage/GroupManageDialog.kt
@@ -10,7 +10,6 @@ import android.view.View
 import android.view.ViewGroup
 import android.widget.EditText
 import androidx.appcompat.widget.Toolbar
-import androidx.lifecycle.Observer
 import androidx.recyclerview.widget.LinearLayoutManager
 import io.legado.app.App
 import io.legado.app.R
@@ -63,7 +62,7 @@ class GroupManageDialog : BaseDialogFragment(), Toolbar.OnMenuItemClickListener
         tv_ok.setTextColor(requireContext().accentColor)
         tv_ok.visible()
         tv_ok.onClick { dismiss() }
-        App.db.rssSourceDao().liveGroup().observe(viewLifecycleOwner, Observer {
+        App.db.rssSourceDao().liveGroup().observe(viewLifecycleOwner, {
             val groups = linkedSetOf<String>()
             it.map { group ->
                 groups.addAll(group.splitNotBlank(",", ";"))
diff --git a/app/src/main/java/io/legado/app/ui/rss/source/manage/RssSourceActivity.kt b/app/src/main/java/io/legado/app/ui/rss/source/manage/RssSourceActivity.kt
index d28ae94a8..2f9050f37 100644
--- a/app/src/main/java/io/legado/app/ui/rss/source/manage/RssSourceActivity.kt
+++ b/app/src/main/java/io/legado/app/ui/rss/source/manage/RssSourceActivity.kt
@@ -11,7 +11,6 @@ import androidx.appcompat.widget.PopupMenu
 import androidx.appcompat.widget.SearchView
 import androidx.documentfile.provider.DocumentFile
 import androidx.lifecycle.LiveData
-import androidx.lifecycle.Observer
 import androidx.recyclerview.widget.DiffUtil
 import androidx.recyclerview.widget.ItemTouchHelper
 import androidx.recyclerview.widget.LinearLayoutManager
@@ -142,7 +141,7 @@ class RssSourceActivity : VMBaseActivity<RssSourceViewModel>(R.layout.activity_r
     }
 
     private fun initLiveDataGroup() {
-        App.db.rssSourceDao().liveGroup().observe(this, Observer {
+        App.db.rssSourceDao().liveGroup().observe(this, {
             groups.clear()
             it.map { group ->
                 groups.addAll(group.splitNotBlank(",", ";"))
@@ -195,7 +194,7 @@ class RssSourceActivity : VMBaseActivity<RssSourceViewModel>(R.layout.activity_r
             } else {
                 App.db.rssSourceDao().liveSearch("%$key%")
             }
-        sourceLiveData?.observe(this, Observer {
+        sourceLiveData?.observe(this, {
             val diffResult = DiffUtil
                 .calculateDiff(DiffCallBack(adapter.getItems(), it))
             adapter.setItems(it, diffResult)