Book Image

Asynchronous Android

By : Steve Liles
Book Image

Asynchronous Android

By: Steve Liles

Overview of this book

With more than a million apps available from Google Play, it is more important than ever to build apps that stand out from the crowd. To be successful, apps must react quickly to user input, deliver results in a flash, and sync data in the background. The key to this is understanding the right way to implement asynchronous operations that work with the platform, instead of against it. Asynchronous Android is a practical book that guides you through the concurrency constructs provided by the Android platform, illustrating the applications, benefits, and pitfalls of each.Learn to use AsyncTask correctly to perform operations in the background, keeping user-interfaces running smoothly while avoiding treacherous memory leaks. Discover Handler, HandlerThread and Looper, the related and fundamental building blocks of asynchronous programming in Android. Escape from the constraints of the Activity lifecycle to load and cache data efficiently across your entire application with the Loader framework. Keep your data fresh with scheduled tasks, and understand how Services let your application continue to run in the background, even when the user is busy with something else.Asynchronous Android will help you to build well-behaved apps with smooth, responsive user-interfaces that delight users with speedy results and data that's always fresh, and keep the system happy and the battery charged by playing by the rules.
Table of Contents (14 chapters)
Asynchronous Android
Credits
About the Author
About the Reviewers
www.PacktPub.com
Preface
Index

Building responsive apps with Handler


The Handler class is fundamental to the infrastructure of Android apps—together with Looper. It underpins everything that the main thread does—including the invocation of the Activity lifecycle methods.

While Looper takes care of dispatching work on its message-loop thread, Handler provides the means to add work to the message queue belonging to a Looper.

We can create a Handler to submit work to be processed on the main thread simply by creating a new instance of Handler from an Activity lifecycle method such as onCreate, shown as follows:

protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    Handler handler = new Handler();
    // …
}

We could also be explicit that we want to submit work to the main thread by passing a reference to the main Looper instance into the Handler constructor.

Handler handler = new Handler(Looper.getMainLooper());

Exactly what we mean by "work" can be described by subclasses of java.lang...