I'm new to Android was following the code to create a Room Database in Kotlin through the official Android Documentation . [1]: https://developer.android.com/codelabs/android-room-with-a-view-kotlin#7
MY Database Class-
package com.example.android.notesapp
import android.content.Context
import androidx.room.Database
import androidx.room.Room
import androidx.room.RoomDatabase
@Database(entities = arrayOf(Note::class), version = 1, exportSchema = false)
abstract class NoteDatabase : RoomDatabase() {
abstract fun noteDao(): NoteDao
companion object {
// Singleton prevents multiple instances of database opening at the
// same time.
@Volatile
private var INSTANCE: NoteDatabase? = null
fun getDatabase(context: Context): NoteDatabase {
// if the INSTANCE is not null, then return it,
// if it is, then create the database
return INSTANCE ?: synchronized(this) {
val instance = Room.databaseBuilder(
context.applicationContext,
NoteDatabase::class.java,
"note_database"
).build()
INSTANCE = instance
// return instance
instance
}
}
}
}
I'm getting the following errors:-
1) Unresolved reference at this line -> return INSTANCE ?: synchronized(this) ,synchronized ()
error
2) Room.databaseBuilder(
context.applicationContext,
NoteDatabase::class.java,
"note_database")
Here it is showing not enough information to infer type variable t inside .databaseBuilder() and unresolved reference .java
3)@Volatie annotation is showing unresolved reference .
MY Dao Interface
package com.example.android.notesapp
import androidx.lifecycle.LiveData import androidx.room.*
@Dao interface NoteDao {
@Insert(onConflict = OnConflictStrategy.IGNORE) // In case we don't want same data to be inserted
suspend fun insert(note: Note) //coroutines -> background process I/O
@Delete
suspend fun delete(note: Note)
@Query(value = "Select * from notes_table order by id ASC")
fun getAllNotes(): LiveData <List<Note>>
}
My Class for Table -> Note Class
package com.example.android.notesapp
import androidx.room.ColumnInfo
import androidx.room.Entity
import androidx.room.PrimaryKey
@Entity(tableName = "notes_table")
class Note(@ColumnInfo(name = "text") val text: String) {
@PrimaryKey(autoGenerate = true)
var id: Int = 0;
}
P.S. I copied all the dependencies and their version required from the official android site. [1]: https://developer.android.com/codelabs/android-room-with-a-view-kotlin#3 Please help to get rid of these errors.
