NoteDatabase.kt

package com.vferreirati.noteskotlinmvvm.data

import android.content.Context
import androidx.room.Database
import androidx.room.Room
import androidx.room.RoomDatabase

@Database(entities = [Note::class], version = 1)
abstract class NoteDatabase : RoomDatabase() {

    abstract fun noteDao(): NoteDao

    companion object {
        private var INSTANCE: NoteDatabase? = null

        fun getInstance(context: Context) : NoteDatabase? {
            if(INSTANCE == null) {
                synchronized(NoteDatabase::class.java) {
                    if(INSTANCE == null) {
                        INSTANCE = Room.databaseBuilder(
                                context.applicationContext,
                                NoteDatabase::class.java,
                                "notes.db")
                                .build()
                    }
                }
            }

            return INSTANCE
        }
    }
}