Introduction

In the previous chapter, you learned how to structure your code and how to save data. In the activity, you also had the opportunity to build a repository and use it to access data and save data through Room. You probably asked the question: Why do you need this repository? This chapter will seek to answer that. With the repository pattern, you will be able to retrieve data from a server and store it locally in a centralized way. The pattern is useful in situations where the same data is required in multiple places, thereby avoiding code duplication while also keeping ViewModels clean of any unnecessary extra logic.

If you look into the Settings app on your device, or the Settings feature of many apps, you will see some similarities. A list of items with toggles that can be on or off. This is achieved through SharedPreferences and PreferenceFragments. SharedPreferences is a way that allows you to store values in a file in key-value pairs. It has specialized mechanisms...