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Asynchronous Android Programming

Asynchronous Android Programming

By : Vasconcelos, Liles
5 (3)
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Asynchronous Android Programming

Asynchronous Android Programming

5 (3)
By: Vasconcelos, 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 (14 chapters)
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2
2. Performing Work with Looper, Handler, and HandlerThread
13
Index

Calling C functions from Java code


The powerful JNI interface, as referred to before, is able to manage interaction in both directions, from Java to C and from C to Java.

A regular Java class declaring a method with the keyword native declares that the method behavior is implemented in native code. Like a regular Java method, the JNI native method is able to receive Java objects or primitive types as arguments and return primitive types and objects.

Let's see how a native method definition will look like in a Java class:

public class MyNativeActivity extends Activity {

  @Override
  protected void onCreate(Bundle savedInstanceState) {
    ...
    cTv.setText(isPrime(2) ? "true" : "false");
  }
  …
  private native boolean isPrime(int number );
}

The preceding activity will call the native code to check whether a number is prime or not and print the result on the UI.

Notice that our function receives a primitive as an argument and return a primitive boolean as a result and does not have any...

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