Today we will examine Android AsyncTasks by building an example app that uses one. Our goal will be to use abstract AsyncTasks so as not to overwhelm Android applications with background tasks.
Asynctask For Android
Utilizing Android's AsyncTask abstract class allows us to run computationally intensive processes in the background without impacting application responsiveness or the UI thread.
An Android application runs on one thread when starting up; tasks that take a long time to fetch responses could make your app unresponsive due to this single-thread technique.
To prevent this situation from arising, we employ AsyncTask on its thread for these lengthy processes and then deliver their output back onto our main UI thread, ensuring it remains responsive throughout.
When used properly, AsyncTask can keep a common application errors responsive UI thread active throughout all time and provides you with unimpeded use when running computationally intensive processes in the background thread, ensuring continuous responsive UI thread operation throughout the application lifecycle.
AsyncTask was designed to allow for accurate and convenient usage of the user interface thread; however, its most frequent application involved integration, leading to issues when settings were updated or missed callbacks occurred, leading to context leakage issues as a result of settings updates being updated or missed callbacks not responding promptly enough.
AsyncTask also handles exceptions thrown by doInBackground and works differently depending on the platform version; its main benefit lies in serving as an easier threading system than executors directly.
AsyncTask should only serve as an easier means of threading these two classes together and not serve as a general-purpose threading system.
Async tasks are best suited for short processes lasting no more than seconds; for longer-running threads, it may be beneficial to utilize various APIs from Java. Utilize. Concurrent packages such as Executor, ThreadPoolExecutor and FutureTask.
Three generic types (Params, Progress task and Result) and four stages (onPreExecute, doInBackground, on Progress Update and onPostExecute) make up an asynchronous task in the Android AsyncTask class.
These generic types may be listed here as well:
- At Completion: Parameters parameters supplied with each job.
- Advancements: Progress shared during background calculation.
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Step-By-Step AsyncTask Tutorial In Android Studio
We may execute instructions asynchronously on Android using AsyncTask , before returning our main thread into sync once completed.
At least one method, doing background (Params), will likely be overridden more frequently onPostExecute(Result).
The AsyncTask class provides tasks in the background that result in user interface (UI) updates. We primarily utilized it for quick tasks that didn't interfere with our main thread.
Execute() serves to launch AsyncTask class processes asynchronously; onPreExecute() is called for each process while doing background () runs background processes while onPostExecute() is invoked for updating user interface updates.
Android Requires AsyncTask
Application code typically executes on the main thread; as each statement is executed sequentially until they have all completed their task(s).
When longer processes need to take place concurrently with one another, we block our main thread until everything has completed its task(s). Our program should leverage the AsyncTasks class, which runs in its thread, to offer users an optimal experience.
Doing the work in doInBackground() will be performed by this class on an independent thread that does not form part of the GUI's views via the onPostExecute() function that resynchronizes itself back with the main UI thread after doInBackground has finished processing tasks automatically.
Once this function has completed its heavy task, this method is automatically invoked again.
Also Read: Transform Your App: The Impact Of Android & Wear OS Integration
Execute AsyncTask Class Execution From Main Thread
Executing AsyncTask classes follows this syntax. Private Class DownloadFilesTask() has recently been added as one such task to an Android device's list; perform (url2,url3,url1) then.
In total, there are four generic AsyncTask types on any given Android device:
AsyncTask In Android
An AsyncTask can be implemented using four distinct phases or methods, known collectively as AsyncTasks methods.
onPreExecute(): This function is called prior to running any job on the main UI thread and serves to set up for its execution - such as showing a Progress Dialog or ProgressBar within its user interface (UI).
doInBackground(Params): It is executed after onPreExecute() completes its execution on the background thread and serves to perform laborious background tasks that need completing asynchronously.
At this phase, parameters of an asynchronous job to execute are received as input parameters to this phase and returned through the onPostExecutes() step/method as its outcome; publishProgress(Progress...) can also be used within this step to publish units of progress that will then appear as progress bar updates on main UI thread under onProgressUpdate(Progress...) method.
onProgressUpdate(Progress...): When publishingProgress(Progress...) is called, this function will be called on the main user interface thread at an unknown execution timing to display progress of any kind while background processes run in parallel with user interactions.
We can additionally update the progress status for an improved user experience.
onPostExecute(Result): After completion of background actions performed within doInBackground function, this phase receives its results as input parameter and we simply update the user interface accordingly to show them off.
AsyncTask Rules: In Order For This Class To Function Efficiently, Several Threading Rules Need To Be Observed
This class should automatically load when using JELLY_BEAN as its base name. The user interface thread must generate task objects for creation.
Lastly, to access and implement this solution successfully, the user interface thread should invoke the execute(Params...) function, which executes it.
For optimal user experience, run the class once and allow onPreExecute(), onPostExecute(Result), doing background (Params), and onProgressUpdate(Progress) to trigger automatically.
Discover: The Outcome Of Background Calculations
Android includes an abstract class named AsyncTask that allows us to perform demanding operations in the background while maintaining a light user interface thread, improving the responsiveness of apps.
When an Android program starts running, only one thread will be active at any one time.
Long running Tasks taking longer may result in this single-thread approach becoming unresponsive, leading to potential program unavailability.
Android AsyncTask class helps us complete complex operations on its thread while passing results back into the UI thread to maintain responsive UI experience. Below are key methods of an AsyncTask class in an Android app:
Doing Background (): This function includes code that should run in the background. Using publish Progress(), we may transmit results back to the UI thread multiple times as part of this procedure; to indicate completion, use onPreExecute() return statements:
PostExecute(): After the background has completed processing, this function is activated as part of post-execution.
DoInBackground results are passed to the onProgress Update() function for use by this function in updating UI thread using progress updates sent from doInBackground and via publishProgress method.
Below Are Three Generic Types That Make Up An Android AsyncTask Class
Params: These parameters will be provided when running a job.
Progress Units Released During Background Calculations: These units indicate how progress was released throughout the background calculation.
Results: Output from background computation
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Example Of Android AsyncTask Class
To initiate an AsyncTask, the MainActivity class needs the following code snippet. (MyTask).execute(); new MyTask(myTask);
Note that in this example, a background thread is initiated using execute on an example class name that implements AsyncTask.
Please keep this in mind:
- The AsyncTask object must be created and executed on the User Interface thread.
- No need exists for manually calling AsyncTask's overridden methods; these will get called automatically.
- AsyncTask can only be called once.
Any subsequent calls will result in an exception being raised.
- We will create an AsyncTask in this tutorial that allows a process to sleep for any periods of time specified by a user.
An AsyncTask Examples In Android Studio
AsyncTask class is used in this step-by-step example to carry out network tasks, specifically retrieval from API (web service) data to be shown within the user interface initially.
We begin by developing a button which when clicked triggers our AsyncTasks class that fetches this data in background while receiving its response through the postExecute() method that displays the same into our user interface (UI).
Download and run the code provided, inspect its finished result and follow its detailed instructions as an example:
Step 1: Create an asynctask android example project.
Step 2: Add Picasso library requirements by opening the build. Gradle and editing build.Gradle files.
Step 3: Add the following code into activity_main.xml (or main.xml). In order to display API data, we first create ImageViews, TextViews and Buttons as click event listeners before connecting all these entities via I/O events.
Step 4: Navigating to MainActivity.java by going into its source tree by going to src > package
At first, we acquired references for ImageViews, TextViews and Buttons during this phase. Once these have been obtained, we use the AsyncTasks class to set OnClickListener events on buttons using AsyncTasks API doing background function once the form of Progress Dialog was displayed in the onPreExecute method.
Once we receive a response, we parse JSON data received back through Picasso Library to display the Title, Category and Image in the user interface (UI).
Conclusion
AsyncTask on Android is essential to developers seeking to speed up and increase the responsiveness of apps; this tutorial offers a thorough introduction covering its purpose as well as using it effectively in practical scenarios.
Developers may leverage their abilities for background processes while improving user experience overall by following this comprehensive tutorial; similarly, network operators may leverage AsyncTask effectively while producing applications that meet current standards while satisfying users' expectations with greater ease if they possess an in-depth knowledge of AsyncTask.
Paul is a highly skilled Full Stack Developer with a solid educational background that includes a Bachelor's degree in Computer Science and a Master's degree in Software Engineering, as well as a decade of hands-on experience. Certifications such as AWS Certified Solutions Architect, and Agile Scrum Master bolster his knowledge. Paul's excellent contributions to the software development industry have garnered him a slew of prizes and accolades, cementing his status as a top-tier professional. Aside from coding, he finds relief in her interests, which include hiking through beautiful landscapes, finding creative outlets through painting, and giving back to the community by participating in local tech education programmer.
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