Book Image

Asynchronous Android Programming - Second Edition

By : Steve Liles
Book Image

Asynchronous Android Programming - Second Edition

By: Steve Liles

Overview of this book

Asynchronous programming has acquired immense importance in Android programming, especially when we want to make use of the number of independent processing units (cores) available on the most recent Android devices. With this guide in your hands you’ll be able to bring the power of Asynchronous programming to your own projects, and make your Android apps more powerful than ever before! To start with, we will discuss the details of the Android Process model and the Java Low Level Concurrent Framework, delivered by Android SDK. We will also guide you through the high-level Android-specific constructs available on the SDK: Handler, AsyncTask, and Loader. Next, we will discuss the creation of IntentServices, Bound Services and External Services, which can run in the background even when the user is not interacting with it. You will also discover AlarmManager and JobScheduler APIs, which are used to schedule and defer work without sacrificing the battery life. In a more advanced phase, you will create background tasks that are able to execute CPU-intensive tasks in a native code-making use of the Android NDK. You will be then guided through the process of interacting with remote services asynchronously using the HTTP protocol or Google GCM Platform. Using the EventBus library, we will also show how to use the Publish-Subscribe software pattern to simplify communication between the different Android application components by decoupling the event producer from event consumer. Finally, we will introduce RxJava, a popular asynchronous Java framework used to compose work in a concise and reactive way. Asynchronous Android will help you to build well-behaved applications with smooth responsive user interfaces that delight the users with speedy results and data that’s always fresh.
Table of Contents (19 chapters)
Asynchronous Android Programming Second Edition
Credits
About the Author
About the Reviewer
www.PacktPub.com
Preface
2
Performing Work with Looper, Handler, and HandlerThread
Index

Controlling the level of concurrency


So far, we've carefully avoided being too specific about what exactly happens when we invoke the AsyncTask execute method. We know that doInBackground() will execute off the main thread, but what exactly does that mean?

The original goal of AsyncTask was created to help developers avoid blocking the main thread. In its initial form at API level 3, AsyncTasks were queued and executed serially (that is, one after the other) on a single background thread, guaranteeing that they would complete in the order they were started.

This changed in API level 4 to use a pool of up to 128 threads to execute multiple AsyncTasks concurrently with each other—a level of concurrency of up to 128. At first glance, this seems like a good thing, since a common use case for AsyncTask is to perform blocking I/O, where the thread spends much of its time idly waiting for data.

However, as we saw in Chapter 1, Building Responsive Android Applications, there are many issues that commonly...