feat: 优化代码

app/src/main/java/io/legado/app/data/dao/BookGroupDao.kt

@@ -13,8 +13,8 @@ interface BookGroupDao {
     @Query("SELECT * FROM book_groups ORDER BY `order`")
     fun liveDataAll(): LiveData<List<BookGroup>>
 
-    @get:Query("SELECT MAX(groupId) FROM book_groups")
-    val maxId: Int
+    @get:Query("SELECT count(groupId) FROM book_groups")
+    val idsCount: Int
 
     @get:Query("SELECT MAX(`order`) FROM book_groups")
     val maxOrder: Int

app/src/main/java/io/legado/app/ui/book/group/GroupViewModel.kt

@@ -9,8 +9,13 @@ class GroupViewModel(application: Application) : BaseViewModel(application) {
 
     fun addGroup(groupName: String) {
         execute {
+            var id = 1
+            val idsCount = App.db.bookGroupDao().idsCount
+            while (id and idsCount != 0) {
+                id *= 2
+            }
             val bookGroup = BookGroup(
-                groupId = App.db.bookGroupDao().maxId.plus(1),
+                groupId = id,
                 groupName = groupName,
                 order = App.db.bookGroupDao().maxOrder.plus(1)
             )