Chapter 17. Data Persistence and Sharing

In this chapter, we will look at a couple of different ways to save data to an Android device's permanent storage. Also, for the first time, we will add a second Activity to our app. It often makes sense when implementing a separate "screen," such as a settings screen, in our app to do so in a new Activity. We could go to the trouble of hiding the original UI and then showing the new UI, but this would quickly lead to confusing and error-prone code. So, we will see how to add an Activity and navigate the user between them.

In summary, in this chapter, we will do the following:

• Learn about Android Intents to switch Activity and pass data
• Create a simple (very simple) settings screen in a new Activity
• Persist the settings screen data using the SharedPreferences class
• Learn about JavaScript Object Notation (JSON) for serialization
• Explore Java's try-catch-finally
• Implement saving data in our Note to Self app