Saving Data on Android

Chapter 10: Data Migration
: Every Database has a lifecycle and needs to be 
updated. Applications continuously change and it's important to update the 
schema of a DB without losing any data or relations. In this chapter, you'll learn 
how to manage data migrations with Room in a simple and declarative way.
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5
Chapter 5: Room 
Architecture
By Aldo Olivares
In the previous section, you learned all the basics behind data storage on Android. 
You learned how to work with permissions, shared preferences, content providers 
and 
SQLite
.
Shared preferences are very useful when you need to store and share simple data, 
such as user preferences as key-value pairs. The main drawback is that you can't 
store large amounts of data since it's not efficient and there's no way to use queries 
to retrieve information.
SQLite is a fast, lightweight local database natively supported by Android that allows 
you to store large amounts of data in a structured way. The only downside of SQLite 
is that its syntax is not very intuitive since the way to interact with it can be very 
different from platform to platform.
Therefore, in this chapter, you are going to learn about one of the most popular 
libraries that helps you simplify your interaction with SQLite: 
Room
.
Along the way, you will also learn:
• How Object Relational Mappers work.
• About Room's integration with Google's architecture components
• The basics behind entities, DAOs and Room databases.
• The advantages and disadvantages of Room.
• The app you are going to build in the rest of this section.
Let's dive in!
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