At the end of this chapter, you should be able to understand concurrency in Android and all the different mechanisms to work with it. You should know that there is a main thread where the UI is updated and that we can create background threads to perform other tasks. You must also know the difference between having the app perform a task in the background (in other words, not on the screen) and having the app perform tasks in a background thread. You should also know the importance of software design patterns and be able to implement some of them.

In the next chapter, we will take a look at how to work with list views, we will implement an adapter, and we will discover a new pattern, ViewHolder, which will be the key to understanding the difference between ListView and RecyclerView introduced in Android Lollipop.