Book Image

RxJava Essentials

By : Ivan Morgillo
Book Image

RxJava Essentials

By: Ivan Morgillo

Overview of this book

<p>RxJava—Reactive Extensions for the JVM—is a library for composing asynchronous and event-based programs using Observable sequences for the Java VM, which will help you beat Android platform limitations to create astonishing Android apps.</p> <p>Starting with some quick background information on the Rx .NET library, this book quickly moves on to your first example. You will understand Observables and learn to filter, transform, or merge them in detail. Next, you will learn how to get rid of Threads, AsyncTasks, and Handlers with Schedulers to create a smooth user experience. Develop an easy, ready-to-go approach to REST API communications and enrich your skills by working with new challenging examples.</p> <p>By the end of the book, you will have explored the reactive programming world and will have created your first Android app without having to think about threading, networking, concurrency, and collection management.</p> <p>The images have been taken from&nbsp;<a href="http://reactivex.io/" target="_blank">http://reactivex.io/</a> which is licensed under a Create Commons 3.0 Attribution license (<a href="https://creativecommons.org/licenses/by/4.0/" target="_blank">https://creativecommons.org/licenses/by/4.0/</a>)</p>
Table of Contents (15 chapters)

Nonblocking I/O operations


Now that we know how to schedule a task on an I/O-specific Scheduler, we can modify our storeBitmap() function and check the StrictMode violation again. For the sake of our example, we can rearrange the code in a new blockingStoreBitmap() function:

private static void blockingStoreBitmap(Context context,  Bitmap bitmap, String filename) {
    FileOutputStream fOut = null;
try {
        fOut = context.openFileOutput(filename,  Context.MODE_PRIVATE);
        bitmap.compress(Bitmap.CompressFormat.PNG, 100, fOut);
        fOut.flush();
        fOut.close();
    } catch (Exception e) {
        throw new RuntimeException(e);
    } finally {
try {
if (fOut != null) {
    fOut.close();
    }
} catch (IOException e) {
    throw new RuntimeException(e);
  }
 }
}

Now, we create our nonblocking version using Schedulers.io():

public static void storeBitmap(Context context, Bitmap  bitmap, String filename) {
    Schedulers.io().createWorker().schedule(() -> {
blockingStoreBitmap...