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In this article, the editor introduces in detail "how to achieve asynchronous tasks in Android". The content is detailed, the steps are clear, and the details are handled properly. I hope this article "how to achieve asynchronous tasks in Android" can help you solve your doubts.

To solve the problem that new threads cannot update UI components, Android provides several solutions

Use Hanlder

Acitity.renOnuiThread (Runnable)

View.post (Runnable)

View.postDelayed (Runnable,long)

.

The operation of Hanlder is actually quite OK, mainly because the latter methods may make programming a little boring. At this time, using AsyncTask can simplify this operation.

AsyncTask is an abstract class that is usually used to be inherited, which requires the waist to specify these three generic parameters.

Parans: type of input parameter to start task execution

Progress: the type of progress value completed by the background task

Result: the type of result returned after the background execution task is completed

It only takes three steps to use asynchronous operation.

Create a subclass of AsyncTask and specify the type for the three generic parameters

The method of realizing AsyncTask

Call the execute of a subclass of AsyncTask to start executing a time-consuming task

Rules that must be followed when using execute

You must create an instance of AsyncTask in the UI thread

The execute method of an instance of AsyncTask must be created in the UI thread

The methods of AsyncTask should be called by the Android system, not by the programmer

Each AsyncTask can only be executed once, and an exception will be thrown multiple times

The methods of AsyncTask are as follows

DoInBackground (Params...)

OnProgressUpdate (Progress...values)

OnPreExecute ()

OnPoxtExecute ()

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