Room databasebuilder not enough information to infer type variable T

itsmebil 0
Viewed 35

I'm new in room database and I have problem with Room.databasebuilder that shown an error not enough information to infer type variable T.

Here is my code

@Database(entities = [ThreadTable::class, GambarThreadTable::class], version = 2, exportSchema = false)
abstract class ThreadDb: RoomDatabase() {
    companion object{
        private var instance: ThreadDb? = null

        fun getDb(context: Context): ThreadDb{
            if (instance == null){
                instance = Room.databaseBuilder(context.applicationContext, ThreadDb::class.java, "ThreadDb")
                    .fallbackToDestructiveMigration()
                    .build()
            }
            return instance as ThreadDb
        }
    }

    abstract fun daoThread() : DaoThread
}

Room version

    def room_version = "2.4.3"
    implementation "androidx.room:room-runtime:$room_version"
    implementation "androidx.room:room-ktx:$room_version"
    kapt "androidx.room:room-compiler:$room_version"

The error occurs on ThreadDb::class.java, what should I change ? I have checked and tried some tutorials but nothing changed.

android-room kotlin android
1 Answers

I just tried your code and did not get any error.
Alternatively, you could try something like this:

@Database(entities = [ThreadTable::class, GambarThreadTable::class], version = 2, exportSchema = false)
abstract class ThreadDb : RoomDatabase() {

    abstract fun daoThread(): DaoThread

    companion object {

        private val sLockObject = Object()

        @Volatile
        private lateinit var INSTANCE: ThreadDb

        fun getInstance(context: Context): ThreadDb {
            if (!isInitialized()) {
                synchronized(sLockObject) {
                    val name = "ThreadDb"
                    Room.databaseBuilder(context, ThreadDb::class.java, name)
                        .fallbackToDestructiveMigration()
                        .build().also { instance -> INSTANCE = instance }
                }

            }
            
            return INSTANCE
        }

        private fun isInitialized() = ::INSTANCE.isInitialized
    }
}
DarShan0
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