Async Task in Android

import android.app.Activity;
import android.app.ProgressDialog;
import android.content.DialogInterface;
import android.os.AsyncTask;
import android.os.Bundle;
import android.util.Log;
import android.view.View;
import android.view.View.OnClickListener;
import android.widget.Button;
import android.widget.Toast;


public class AsyncTasks extends Activity {
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.main);


Button upload = (Button) findViewById(R.id.widget27);


upload.setOnClickListener(new OnClickListener() {
public void onClick(View pV) {
new DoInBackground().execute();

}
});
}


public void do_update() {

// your stuff here
Log.i("MSG", "msg");

}


private class DoInBackground extends AsyncTask<Void, Void, Void> implements
DialogInterface.OnCancelListener {
private ProgressDialog dialog;


protected void onPreExecute() {
dialog = ProgressDialog.show(AsyncTasks.this, "", "Busy...", true, true,
this);
}


protected Void doInBackground(Void... v) {
do_update();
return null;
}


protected void onPostExecute(Void v) {
dialog.dismiss();
}


public void onCancel(DialogInterface dialog) {
cancel(true);
dialog.dismiss();
}
}
}