diff --git a/app/src/main/java/com/hippo/ehviewer/dao/BasicDao.kt b/app/src/main/java/com/hippo/ehviewer/dao/BasicDao.kt
index 511bf3f22..836706af3 100644
--- a/app/src/main/java/com/hippo/ehviewer/dao/BasicDao.kt
+++ b/app/src/main/java/com/hippo/ehviewer/dao/BasicDao.kt
@@ -1,9 +1,6 @@
-package com.hippo.ehviewer.dao;
+package com.hippo.ehviewer.dao
 
-import java.util.List;
-
-public interface BasicDao<T> {
-    List<T> list();
-
-    long insert(T t);
-}
+interface BasicDao<T> {
+    fun list(): List<T>
+    fun insert(t: T): Long
+}
\ No newline at end of file
diff --git a/app/src/main/java/com/hippo/ehviewer/dao/BookmarksDao.kt b/app/src/main/java/com/hippo/ehviewer/dao/BookmarksDao.kt
index 1b276247a..f50c304e1 100644
--- a/app/src/main/java/com/hippo/ehviewer/dao/BookmarksDao.kt
+++ b/app/src/main/java/com/hippo/ehviewer/dao/BookmarksDao.kt
@@ -1,20 +1,18 @@
-package com.hippo.ehviewer.dao;
+package com.hippo.ehviewer.dao
 
-import androidx.room.Dao;
-import androidx.room.Delete;
-import androidx.room.Insert;
-import androidx.room.Query;
-
-import java.util.List;
+import androidx.room.Dao
+import androidx.room.Delete
+import androidx.room.Insert
+import androidx.room.Query
 
 @Dao
-public interface BookmarksDao extends BasicDao<BookmarkInfo> {
+interface BookmarksDao : BasicDao<BookmarkInfo> {
     @Insert
-    long insert(BookmarkInfo bookmark);
+    override fun insert(t: BookmarkInfo): Long
 
     @Delete
-    void delete(BookmarkInfo bookmark);
+    fun delete(bookmark: BookmarkInfo)
 
     @Query("SELECT * FROM BOOKMARKS ORDER BY TIME DESC")
-    List<BookmarkInfo> list();
-}
+    override fun list(): List<BookmarkInfo>
+}
\ No newline at end of file
diff --git a/app/src/main/java/com/hippo/ehviewer/dao/DownloadDirnameDao.kt b/app/src/main/java/com/hippo/ehviewer/dao/DownloadDirnameDao.kt
index 0226ac31f..747b6079f 100644
--- a/app/src/main/java/com/hippo/ehviewer/dao/DownloadDirnameDao.kt
+++ b/app/src/main/java/com/hippo/ehviewer/dao/DownloadDirnameDao.kt
@@ -1,29 +1,27 @@
-package com.hippo.ehviewer.dao;
+package com.hippo.ehviewer.dao
 
-import androidx.room.Dao;
-import androidx.room.Insert;
-import androidx.room.Query;
-import androidx.room.Update;
-
-import java.util.List;
+import androidx.room.Dao
+import androidx.room.Insert
+import androidx.room.Query
+import androidx.room.Update
 
 @Dao
-public interface DownloadDirnameDao extends BasicDao<DownloadDirname> {
+interface DownloadDirnameDao : BasicDao<DownloadDirname> {
     @Query("SELECT * FROM DOWNLOAD_DIRNAME WHERE GID = :gid")
-    DownloadDirname load(long gid);
+    fun load(gid: Long): DownloadDirname?
 
     @Update
-    void update(DownloadDirname downloadDirname);
+    fun update(downloadDirname: DownloadDirname)
 
     @Insert
-    long insert(DownloadDirname downloadDirname);
+    override fun insert(t: DownloadDirname): Long
 
     @Query("DELETE FROM DOWNLOAD_DIRNAME WHERE GID = :gid")
-    void deleteByKey(long gid);
+    fun deleteByKey(gid: Long)
 
     @Query("DELETE FROM DOWNLOAD_DIRNAME")
-    void deleteAll();
+    fun deleteAll()
 
     @Query("SELECT * FROM DOWNLOAD_DIRNAME")
-    List<DownloadDirname> list();
-}
+    override fun list(): List<DownloadDirname>
+}
\ No newline at end of file
diff --git a/app/src/main/java/com/hippo/ehviewer/dao/DownloadLabel.kt b/app/src/main/java/com/hippo/ehviewer/dao/DownloadLabel.kt
index f1b51a7d3..6c73152e0 100644
--- a/app/src/main/java/com/hippo/ehviewer/dao/DownloadLabel.kt
+++ b/app/src/main/java/com/hippo/ehviewer/dao/DownloadLabel.kt
@@ -1,40 +1,18 @@
-package com.hippo.ehviewer.dao;
+package com.hippo.ehviewer.dao
 
-import androidx.room.ColumnInfo;
-import androidx.room.Entity;
-import androidx.room.PrimaryKey;
+import androidx.room.ColumnInfo
+import androidx.room.Entity
+import androidx.room.PrimaryKey
 
 @Entity(tableName = "DOWNLOAD_LABELS")
-public class DownloadLabel {
+class DownloadLabel {
     @PrimaryKey
     @ColumnInfo(name = "_id")
-    private Long id;
+    var id: Long? = null
+
     @ColumnInfo(name = "LABEL")
-    private String label;
+    var label: String? = null
+
     @ColumnInfo(name = "TIME")
-    private long time;
-
-    public Long getId() {
-        return id;
-    }
-
-    public void setId(Long id) {
-        this.id = id;
-    }
-
-    public String getLabel() {
-        return label;
-    }
-
-    public void setLabel(String label) {
-        this.label = label;
-    }
-
-    public long getTime() {
-        return time;
-    }
-
-    public void setTime(long time) {
-        this.time = time;
-    }
-}
+    var time: Long = 0
+}
\ No newline at end of file
diff --git a/app/src/main/java/com/hippo/ehviewer/dao/DownloadLabelDao.kt b/app/src/main/java/com/hippo/ehviewer/dao/DownloadLabelDao.kt
index 29f552c51..f7c8dc40d 100644
--- a/app/src/main/java/com/hippo/ehviewer/dao/DownloadLabelDao.kt
+++ b/app/src/main/java/com/hippo/ehviewer/dao/DownloadLabelDao.kt
@@ -1,30 +1,28 @@
-package com.hippo.ehviewer.dao;
+package com.hippo.ehviewer.dao
 
-import androidx.room.Dao;
-import androidx.room.Delete;
-import androidx.room.Insert;
-import androidx.room.Query;
-import androidx.room.Update;
-
-import java.util.List;
+import androidx.room.Dao
+import androidx.room.Delete
+import androidx.room.Insert
+import androidx.room.Query
+import androidx.room.Update
 
 @Dao
-public interface DownloadLabelDao extends BasicDao<DownloadLabel> {
+interface DownloadLabelDao : BasicDao<DownloadLabel> {
     @Query("SELECT * FROM DOWNLOAD_LABELS ORDER BY TIME ASC")
-    List<DownloadLabel> list();
+    override fun list(): List<DownloadLabel>
 
     @Query("SELECT * FROM DOWNLOAD_LABELS ORDER BY TIME ASC LIMIT :limit OFFSET :offset")
-    List<DownloadLabel> list(int offset, int limit);
+    fun list(offset: Int, limit: Int): List<DownloadLabel>
 
     @Update
-    void update(List<DownloadLabel> downloadLabels);
+    fun update(downloadLabels: List<DownloadLabel>)
 
     @Update
-    void update(DownloadLabel downloadLabel);
+    fun update(downloadLabel: DownloadLabel)
 
     @Insert
-    long insert(DownloadLabel downloadLabel);
+    override fun insert(t: DownloadLabel): Long
 
     @Delete
-    void delete(DownloadLabel downloadLabel);
-}
+    fun delete(downloadLabel: DownloadLabel)
+}
\ No newline at end of file
diff --git a/app/src/main/java/com/hippo/ehviewer/dao/DownloadsDao.kt b/app/src/main/java/com/hippo/ehviewer/dao/DownloadsDao.kt
index 8e6fc61e4..234c4d79c 100644
--- a/app/src/main/java/com/hippo/ehviewer/dao/DownloadsDao.kt
+++ b/app/src/main/java/com/hippo/ehviewer/dao/DownloadsDao.kt
@@ -1,27 +1,25 @@
-package com.hippo.ehviewer.dao;
+package com.hippo.ehviewer.dao
 
-import androidx.room.Dao;
-import androidx.room.Delete;
-import androidx.room.Insert;
-import androidx.room.Query;
-import androidx.room.Update;
-
-import java.util.List;
+import androidx.room.Dao
+import androidx.room.Delete
+import androidx.room.Insert
+import androidx.room.Query
+import androidx.room.Update
 
 @Dao
-public interface DownloadsDao extends BasicDao<DownloadInfo> {
+interface DownloadsDao : BasicDao<DownloadInfo> {
     @Query("SELECT * FROM DOWNLOADS ORDER BY TIME DESC")
-    List<DownloadInfo> list();
+    override fun list(): List<DownloadInfo>
 
     @Query("SELECT * FROM DOWNLOADS WHERE GID = :gid")
-    DownloadInfo load(long gid);
+    fun load(gid: Long): DownloadInfo?
 
     @Update
-    void update(DownloadInfo downloadInfo);
+    fun update(downloadInfo: DownloadInfo)
 
     @Insert
-    long insert(DownloadInfo downloadInfo);
+    override fun insert(downloadInfo: DownloadInfo): Long
 
     @Delete
-    void delete(DownloadInfo downloadInfo);
-}
+    fun delete(downloadInfo: DownloadInfo)
+}
\ No newline at end of file
diff --git a/app/src/main/java/com/hippo/ehviewer/dao/FilterDao.kt b/app/src/main/java/com/hippo/ehviewer/dao/FilterDao.kt
index 03c89b655..4d0682cf9 100644
--- a/app/src/main/java/com/hippo/ehviewer/dao/FilterDao.kt
+++ b/app/src/main/java/com/hippo/ehviewer/dao/FilterDao.kt
@@ -1,27 +1,25 @@
-package com.hippo.ehviewer.dao;
+package com.hippo.ehviewer.dao
 
-import androidx.room.Dao;
-import androidx.room.Delete;
-import androidx.room.Insert;
-import androidx.room.Query;
-import androidx.room.Update;
-
-import java.util.List;
+import androidx.room.Dao
+import androidx.room.Delete
+import androidx.room.Insert
+import androidx.room.Query
+import androidx.room.Update
 
 @Dao
-public interface FilterDao extends BasicDao<Filter> {
+interface FilterDao : BasicDao<Filter> {
     @Query("SELECT * FROM FILTER")
-    List<Filter> list();
+    override fun list(): List<Filter>
 
     @Update
-    void update(Filter filter);
+    fun update(filter: Filter)
 
     @Insert
-    long insert(Filter filter);
+    override fun insert(t: Filter): Long
 
     @Delete
-    void delete(Filter filter);
+    fun delete(filter: Filter)
 
     @Query("SELECT * FROM FILTER WHERE TEXT = :text AND MODE = :mode")
-    Filter load(String text, int mode);
-}
+    fun load(text: String, mode: Int): Filter?
+}
\ No newline at end of file
diff --git a/app/src/main/java/com/hippo/ehviewer/dao/HistoryDao.kt b/app/src/main/java/com/hippo/ehviewer/dao/HistoryDao.kt
index da78e07fb..3cc42a865 100644
--- a/app/src/main/java/com/hippo/ehviewer/dao/HistoryDao.kt
+++ b/app/src/main/java/com/hippo/ehviewer/dao/HistoryDao.kt
@@ -1,40 +1,38 @@
-package com.hippo.ehviewer.dao;
+package com.hippo.ehviewer.dao
 
-import androidx.paging.PagingSource;
-import androidx.room.Dao;
-import androidx.room.Delete;
-import androidx.room.Insert;
-import androidx.room.Query;
-import androidx.room.Update;
-
-import java.util.List;
+import androidx.paging.PagingSource
+import androidx.room.Dao
+import androidx.room.Delete
+import androidx.room.Insert
+import androidx.room.Query
+import androidx.room.Update
 
 @Dao
-public interface HistoryDao extends BasicDao<HistoryInfo> {
+interface HistoryDao : BasicDao<HistoryInfo> {
     @Query("SELECT * FROM HISTORY WHERE GID = :gid")
-    HistoryInfo load(long gid);
+    fun load(gid: Long): HistoryInfo?
 
     @Query("SELECT * FROM HISTORY ORDER BY TIME DESC")
-    List<HistoryInfo> list();
+    override fun list(): List<HistoryInfo>
 
     @Query("SELECT * FROM HISTORY ORDER BY TIME DESC LIMIT :limit OFFSET :offset")
-    List<HistoryInfo> list(int offset, int limit);
+    fun list(offset: Int, limit: Int): List<HistoryInfo>
 
     @Query("SELECT * FROM HISTORY ORDER BY TIME DESC")
-    PagingSource<Integer, HistoryInfo> listLazy();
+    fun listLazy(): PagingSource<Int, HistoryInfo>
 
     @Update
-    void update(HistoryInfo historyInfo);
+    fun update(historyInfo: HistoryInfo)
 
     @Insert
-    long insert(HistoryInfo historyInfo);
+    override fun insert(t: HistoryInfo): Long
 
     @Delete
-    void delete(HistoryInfo historyInfos);
+    fun delete(historyInfo: HistoryInfo)
 
     @Delete
-    void delete(List<HistoryInfo> historyInfos);
+    fun delete(historyInfo: List<HistoryInfo>)
 
     @Query("DELETE FROM HISTORY")
-    void deleteAll();
-}
+    fun deleteAll()
+}
\ No newline at end of file
diff --git a/app/src/main/java/com/hippo/ehviewer/dao/LocalFavoritesDao.kt b/app/src/main/java/com/hippo/ehviewer/dao/LocalFavoritesDao.kt
index 6cc0e8256..4950aa51c 100644
--- a/app/src/main/java/com/hippo/ehviewer/dao/LocalFavoritesDao.kt
+++ b/app/src/main/java/com/hippo/ehviewer/dao/LocalFavoritesDao.kt
@@ -1,29 +1,27 @@
-package com.hippo.ehviewer.dao;
+package com.hippo.ehviewer.dao
 
-import androidx.room.Dao;
-import androidx.room.Delete;
-import androidx.room.Insert;
-import androidx.room.Query;
-
-import java.util.List;
+import androidx.room.Dao
+import androidx.room.Delete
+import androidx.room.Insert
+import androidx.room.Query
 
 @Dao
-public interface LocalFavoritesDao extends BasicDao<LocalFavoriteInfo> {
+interface LocalFavoritesDao : BasicDao<LocalFavoriteInfo> {
     @Query("SELECT * FROM LOCAL_FAVORITES ORDER BY TIME DESC")
-    List<LocalFavoriteInfo> list();
+    override fun list(): List<LocalFavoriteInfo>
 
     @Query("SELECT * FROM LOCAL_FAVORITES WHERE TITLE LIKE :title ORDER BY TIME DESC")
-    List<LocalFavoriteInfo> list(String title);
+    fun list(title: String): List<LocalFavoriteInfo>
 
     @Query("SELECT * FROM LOCAL_FAVORITES WHERE GID = :gid")
-    LocalFavoriteInfo load(long gid);
+    fun load(gid: Long): LocalFavoriteInfo?
 
     @Insert
-    long insert(LocalFavoriteInfo localFavoriteInfo);
+    override fun insert(t: LocalFavoriteInfo): Long
 
     @Delete
-    void delete(LocalFavoriteInfo localFavoriteInfo);
+    fun delete(localFavoriteInfo: LocalFavoriteInfo)
 
     @Query("DELETE FROM LOCAL_FAVORITES WHERE GID = :gid")
-    void deleteByKey(long gid);
-}
+    fun deleteByKey(gid: Long)
+}
\ No newline at end of file
diff --git a/app/src/main/java/com/hippo/ehviewer/dao/QuickSearchDao.kt b/app/src/main/java/com/hippo/ehviewer/dao/QuickSearchDao.kt
index b349e92be..beeffaa45 100644
--- a/app/src/main/java/com/hippo/ehviewer/dao/QuickSearchDao.kt
+++ b/app/src/main/java/com/hippo/ehviewer/dao/QuickSearchDao.kt
@@ -1,30 +1,28 @@
-package com.hippo.ehviewer.dao;
+package com.hippo.ehviewer.dao
 
-import androidx.room.Dao;
-import androidx.room.Delete;
-import androidx.room.Insert;
-import androidx.room.Query;
-import androidx.room.Update;
-
-import java.util.List;
+import androidx.room.Dao
+import androidx.room.Delete
+import androidx.room.Insert
+import androidx.room.Query
+import androidx.room.Update
 
 @Dao
-public interface QuickSearchDao extends BasicDao<QuickSearch> {
+interface QuickSearchDao : BasicDao<QuickSearch> {
     @Query("SELECT * FROM QUICK_SEARCH ORDER BY TIME ASC")
-    List<QuickSearch> list();
+    override fun list(): List<QuickSearch>
 
     @Query("SELECT * FROM QUICK_SEARCH ORDER BY TIME ASC LIMIT :limit OFFSET :offset")
-    List<QuickSearch> list(int offset, int limit);
+    fun list(offset: Int, limit: Int): List<QuickSearch>
 
     @Update
-    void update(List<QuickSearch> downloadLabels);
+    fun update(downloadLabels: List<QuickSearch>)
 
     @Update
-    void update(QuickSearch quickSearch);
+    fun update(quickSearch: QuickSearch)
 
     @Insert
-    long insert(QuickSearch quickSearch);
+    override fun insert(t: QuickSearch): Long
 
     @Delete
-    void delete(QuickSearch quickSearch);
-}
+    fun delete(quickSearch: QuickSearch?)
+}
\ No newline at end of file
diff --git a/app/src/main/java/com/hippo/ehviewer/ui/scene/HistoryScene.kt b/app/src/main/java/com/hippo/ehviewer/ui/scene/HistoryScene.kt
index cdf96f5e6..7e1439096 100644
--- a/app/src/main/java/com/hippo/ehviewer/ui/scene/HistoryScene.kt
+++ b/app/src/main/java/com/hippo/ehviewer/ui/scene/HistoryScene.kt
@@ -304,7 +304,7 @@ class HistoryScene : BaseToolbarScene() {
                         var i = 0
                         val n = labelRawList.size
                         while (i < n) {
-                            labelList.add(labelRawList[i].label)
+                            labelRawList[i].label?.let { labelList.add(it) }
                             i++
                         }
                         val labels = labelList.toTypedArray()