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 CursorLoader


CursorLoader is a specialized subclass of AsyncTaskLoader that uses its lifecycle methods to correctly manage the resources associated with a database Cursor.

A database Cursor is a little like an Iterator, in that it allows you to scroll through a dataset without having to worry where exactly the dataset is coming from or what data structure it is a part of.

We're going to use CursorLoader to query the MediaStore for a list of all images on the device. Because CursorLoader is already implemented to correctly handle all of the details of working with a Cursor, we don't need to subclass it. We can simply instantiate it, passing in the information it needs in order to open the Cursor it should manage for us. We can do this in the onCreateLoader callback:

@Override
public CursorLoader onCreateLoader(int id, Bundle bundle) {
    return new CursorLoader(this,
        MediaStore.Images.Media.EXTERNAL_CONTENT_URI,
        new String[]{
            MediaStore...