By default, application code runs within the main thread. Every statement is therefore executed in sequence. If you perform an extended-lasting operation, the appliance blocks until the corresponding operation has finished. To provide an honest user experience all potentially slow running operations in an Android application should run asynchronously. this will be archived via concurrency constructs of the Java language or of the Android framework. Potentially slow operations are for instance: network, file, and database access, and sophisticated calculations and tasks like them need background processing, let’s dive a little deeper and look at that in detail!
Android modifies the interface and handles input events from one single thread, called the most thread. Android collects all events during this thread during a queue and processes this queue with an instance of the Looper class. The Android Operating System uses the Thread class to perform asynchronous tasks like the ones mentioned above the header image. The java.util.concurrent is also provided by it to perform certain tasks, something which we call background. For instance, by using the ThreadPools and Executor classes.
If you would like to update the interface from a replacement Thread, you would like to synchronize with the most thread. due to these restrictions, Android developers typically use Android-specific code constructs.
Here’s an Example
The RxJava open-source framework allows specifying an observer of an observable stream of knowledge. Once the events happen and are reported finished, the observer is named by the framework. you’ll configure during which thread the observer and observable run.
What Exactly is Background Work?
An app is taken into account to be running within the background as long as each of the subsequent conditions is satisfied:
- The app is not in the running state and no foreground services are performed, while the device was being used.
- None of the app’s activities (pages) or fragments are currently visible the one using it
A simple glyph to understand this process could be taken from the below Image:
fig.1
Categories of Background Tasks
Background tasks fall under one among the subsequent main categories:
- Immediate
- Deferred
- Exact
To categorize a task, answer the subsequent questions, and traverse the corresponding decision tree in (fig 1:)
- Does the task complete itself when the user was/is interacting with the application? Yes? then should this be classified for immediate exec? If not, proceed to the second question.
- Does the task get to run at a particular time? If you are doing got to run a task at a particular time, categorize the task as exact.
Most tasks don’t get to be run at a particular time. Tasks generally leave slight variations in once they run that are supported conditions like network availability and remaining battery.
- Tasks that do not get to be run at a particular time should be categorized as deferred.
These tasks could be used for background processing in Android, Let’s learn more about them in detail:
1. Immediate tasks
For tasks that ought to be executed immediately and wish continued processing, albeit the user puts the appliance in the background or the device restarts, we recommend using WorkManager and its support for long-running tasks. In specific cases, like with media playback or active navigation, you would possibly want to use foreground services directly.
2. Deferred tasks
Every task that’s indirectly connected to user interaction and may run at any time within the future is often deferred. The recommended solution for deferred tasks is WorkManager. The WorkManager makes it quite efficient and easy to schedule the asynchronous and deferrable tasks, even the tasks which need to resume when the phone restarts!
3. Exact tasks
A task that must be executed at a particular point in time and they can use AlarmManager.
Thread & Handler
Initialize the thread with a runnable and then proceed to perform any heavy operation. By default the views have a handler, so you’ll do View.post(). The Handler is that the means of communication between the heavy task running on the created thread and therefore the UI Thread.
Java
Thread thread = new Thread(new Runnable() { @Override public void run() { final String result = performBlockingTask(); // GfG Thread Example runOnUiThread(new Runnable() { @Override public void run() { mTextView.setText(result); } }); }});thread.start(); |
Problems:
- No support for configuration changes, in other words, if our application supports both orientations (landscape and portrait) we’ve to handle the states of the Threads and Handlers when the user rotates his device.
- Boilerplate code and un-friendly read.
- No error handler.
IntentService
Useful when it’s necessary to run tasks within the background that don’t affect the UI. they’re completely decoupled from view, ie they’re not suffering from the life cycle of the Activity.
Java
public class BackgroundServiceGfG extends IntentService { private static final String TAG = BackgroundServiceGfG.class.getSimpleName(); public BackgroundServiceGfG() { super(TAG ); } @Override protected void onHandleIntent(Intent intent) { blockingTask(); }} |
GeekTip: It must be declared within the AndroidManifest.xml a bit like the other Service. It can then be pushed by simply sending an intent (it can even include any parameter!)
Problems:
- Doesn’t have direct communication with the UI.
AsyncTask
Run instructions within the background and synchronize again with the most Thread. Useful for brief background operations. Read More here.
Java
new AsyncTask<Void, Void, String>() { @Override protected void onPreExecute() { // Creating a Sample Async Task } @Override protected String doInBackground(Void... voids) { return performBlockingTask(); } @Override protected void onProgressUpdate(Integer... progress) { mProgessBar.setProgress(progress); } @Override protected void onPostExecute(String result) { mTextView.setText(result); } }.execute(); |
Problems:
- No support for configuration changes.
- No error handler, so we’ve to ask onPostExecute whether the result’s a mistake or not.
Each AsyncTask instance is often executed only/just one time.
Conclusion
With this, we conclude our article on Background Processing, as you could see there are certain issues and problems with the methods, so choosing the right one (suiting your need) should be an easy task!
