64.5 The Room Database

The Room database class is created by extending the RoomDatabase class and acts as a layer on top of the actual SQLite database embedded into the Android operating system. The class is responsible for creating and returning a new room database instance and for providing access to the DAO instances associated with the database.

The Room persistence library provides a database builder for creating database instances. Each Android app should only have one room database instance, so it is best to implement defensive code within the class to prevent more than one instance being created.

An example Room Database implementation for use with the example customer table is outlined in the following code listing:

import android.content.Context;

import android.arch.persistence.room.Database;

import android.arch.persistence.room.Room;

import android.arch.persistence.room.RoomDatabase;

 

@Database(entities = {Customer.class}, version = 1)

public...