AsyncTask Implementation in Android using Java

Anand Kashyap

11 September 2019

AsyncTask

The AsyncTask the class allows to run instructions in the background and to synchronize again with the main thread. It also reports the progress of the running tasks.

You must subclass it so The parameters are the following AsyncTask <TypeOfVarArgParams, ProgressValue, ResultValue>

and AsyncTask is started via the execute() method so this execute() method calls the doInBackground() and the onPostExecute() method.

TypeOfVarArgParams is passed into the doInBackground() method as input.

The doInBackground() the method contains the coding instruction which should be performed in a background thread. This method runs automatically in a separate Thread.

The onPostExecute() method synchronizes itself again with the user interface thread and allows it to be updated.

Example: AsyncTask

The following code demonstrates how to use to download something from the Internet. The code requires the android.permission.INTERNET permission in your Android manifest.

Implementation :

package de.vogella.android.asynctask;


public class MainActivity extends Activity {
  

    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.main);
        
    }

    private class MyAsyncTask extends AsyncTask<Void, Void, Void> {
        @Override
        protected String doInBackground(Void void) {
            // This method is using a worker thread.
            // We can perform the network calls in this method.
        }

        @Override
        protected void onPostExecute(Void void) {
            //Get the data from doInBackground method
        }
    }

    // Triggered via a button in your layout
    public void onClick(View view) {
        MyAsyncTask task = new MyAsyncTask();
        task.execute();

    }
}

package de.vogella.android.asynctask;

public class MainActivity extends Activity {

@Override

public void onCreate(Bundle savedInstanceState) {

super.onCreate(savedInstanceState);

setContentView(R.layout.main);

}

private class MyAsyncTask extends AsyncTask<Void, Void, Void> {

@Override

protected String doInBackground(Void void) {

// This method is using a worker thread.

// We can perform the network calls in this method.

}

@Override

protected void onPostExecute(Void void) {

//Get the data from doInBackground method

}

// Triggered via a button in your layout

public void onClick(View view) {

MyAsyncTask task = new MyAsyncTask();

task.execute();

}