Communication between threads in Android using AsyncTask

AsyncTask in Android is a mechanism used to execute tasks in background threads and communicate with the UI thread.

AsyncTask is essentially a utility class that encapsulates both Thread and Handler, simplifying the process of performing time-consuming operations in the background and updating the UI.

AsynTask allows you to perform time-consuming operations in the background thread and then notify the UI thread for appropriate updates after completion.

AsyncTask has four generic parameters:

1. Params: The type of parameters needed to be passed when executing an AsyncTask.
2. Progress: The type of progress that the background task is executing.
3. Type of return result after the completion of backend tasks.
4. Status: Type of status during the execution process of background tasks.

There are four main methods in AsyncTask that need to be overridden.

1. The onPreExecute() method is called before the background task is executed, typically used for performing some initialization operations, such as displaying a progress bar.
2. Perform time-consuming operations in the background thread, this method will be called after the onPreExecute() method is finished executing.
3. onProgressUpdate(Progress…)：During the execution of a background task, this method can be triggered by calling publishProgress(), allowing for updates to the UI, such as updating a progress bar, to be made within it.
4. The method onPostExecute(Result) will be called after the background task is completed, allowing for UI updates such as displaying the result.

When using AsyncTask, it is necessary to create a subclass that extends AsyncTask and implement the corresponding methods. Then, call the execute() method at the appropriate place to start the task.

In AsyncTask, you can use the publishProgress() method to trigger the execution of onProgressUpdate() method and update the UI in the onProgressUpdate() method.

It is important to note that AsyncTask can only be executed once, meaning a new instance should be created after each execution to perform the next task. Also, when an Activity is destroyed, it is important to ensure the cancellation of any AsyncTask running to prevent memory leaks.