Android pre-populated database (full)

MainActivity.kt

package com.example.example

import android.os.Bundle
import android.support.v7.app.AppCompatActivity

class MainActivity : AppCompatActivity() {

    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)
        
        // This is an example, remember to use a background thread in production.
        val myDatabase = MyDatabaseHelper(this).readableDatabase
        
        myDatabase.rawQuery("SELECT * FROM my_awesome_table")
    }
}

MyDatabaseHelper.kt

package com.example.example

import android.content.Context
import android.content.SharedPreferences
import android.database.sqlite.SQLiteDatabase
import android.database.sqlite.SQLiteOpenHelper
import java.io.File
import java.io.FileOutputStream

class ActsDbHelper(val context: Context) : SQLiteOpenHelper(context, DATABASE_NAME, null, DATABASE_VERSION) {

    private val preferences: SharedPreferences = context.getSharedPreferences(
            "${context.packageName}.database_versions",
            Context.MODE_PRIVATE
    )

    private fun installedDatabaseIsOutdated(): Boolean {
        return preferences.getInt(DATABASE_NAME, 0) < DATABASE_VERSION
    }

    private fun writeDatabaseVersionInPreferences() {
        preferences.edit().apply {
            putInt(DATABASE_NAME, DATABASE_VERSION)
            apply()
        }
    }

    private fun installDatabaseFromAssets() {
        val inputStream = context.assets.open("$ASSETS_PATH/$DATABASE_NAME.sqlite3")

        try {
            val outputFile = File(context.getDatabasePath(DATABASE_NAME).path)
            val outputStream = FileOutputStream(outputFile)

            inputStream.copyTo(outputStream)
            inputStream.close()

            outputStream.flush()
            outputStream.close()
        } catch (exception: Throwable) {
            throw RuntimeException("The $DATABASE_NAME database couldn't be installed.", exception)
        }
    }
    
    @Synchronized
    private fun installOrUpdateIfNecessary() {
        if (installedDatabaseIsOutdated()) {
            context.deleteDatabase(DATABASE_NAME)
            installDatabaseFromAssets()
            writeDatabaseVersionInPreferences()
        }
    }

    override fun getWritableDatabase(): SQLiteDatabase {
        throw RuntimeException("The $DATABASE_NAME database is not writable.")
    }

    override fun getReadableDatabase(): SQLiteDatabase {
        installOrUpdateIfNecessary()
        return super.getReadableDatabase()
    }

    override fun onCreate(db: SQLiteDatabase?) {
        // Nothing to do
    }

    override fun onUpgrade(db: SQLiteDatabase?, oldVersion: Int, newVersion: Int) {
        // Nothing to do
    }

    companion object {
        const val ASSETS_PATH = "databases"
        const val DATABASE_NAME = "mydb"
        const val DATABASE_VERSION = 1
    }

}