Project that demos how AsyncTask can be moved to Fragment so that the AsyncTask when started can continue without it dying in the middle because of Parent Activity's destruction.
- The AsyncTask does not have a corresponding UI
1. Create your AsyncTaskFragment class named something like AsyncTaskFragment extending Fragment, the template for which is below:
public class AsyncTaskFragment extends Fragment {
public interface AsyncTaskInitiator {
void handleTaskUpdate(String message);
}
private AsyncTaskInitiator parentActivity;
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setRetainInstance(true);
}
@Override
public void onAttach(Activity activity) {
super.onAttach(activity);
parentActivity = (AsyncTaskInitiator) activity;
}
public void runAsyncTask(Integer... integers) {
MyAsyncTask myAsyncTask = new MyAsyncTask();
myAsyncTask.execute(integers);
}
class MyAsyncTask extends AsyncTask<Params, Progress, Result> {
@Override
protected Void doInBackground(Params... params) {
for (Integer param : params) {
publishProgress(param.toString());
//TODO
}
return null;
}
@Override
protected void onProgressUpdate(String... values) {
parentActivity.handleTaskUpdate(values[0]);
}
}
}2. Define your AsyncTask class that extends AsyncTask<Params, Progress, Result> something like below:
class MyAsyncTask extends AsyncTask<Params, Progress, Result> {
@Override
protected Void doInBackground(Params... params) {
for (Integer param : params) {
publishProgress(param.toString());
//TODO
}
return null;
}
@Override
protected void onProgressUpdate(String... values) {
parentActivity.handleTaskUpdate(values[0]);
}
}3. Inside that class define an interface something like below:
public interface AsyncTaskInitiator {
void handleTaskUpdate(String message);
}4. The Activity class that starts the AsyncTask should implement the interface defined in the previous step. See sample code below:
public class MainActivity extends Activity implements AsyncTaskInitiator {
@Override
public void handleTaskUpdate(String message) {
//TODO: Update UI
}
}