Question

I’d like my activity to send the same event to multiple fragment. Instead of making my activity calling each individual fragment method : FragmentA.DoTask(), FragmentB.DoTask(), FragmentC.DoTask(), etc… I’d like rather make my activity send only one event and then make the fragment listening to this event.

On the developpers docs they make the activity “listen” to the fragment but then the activity calls the fragments’ methods. Is it possible the other way around : to make the fragments “listen” to the activity.

Thanks

Answer 1

I don’t think there is a way around it. The word “listen” in the docs is more metaphorical. You have to call all fragments explicitly.

The closet thing you can get, is to have a list of Fragment maintained in your Activity class. e.g.: create a customized Fragment class:

public class MyFragment extends Fragment{
  public abstract void doTask();
}

Have all your Fragments inherited from this class.

public class FragmentA extends MyFragment{

  @Override
  public void doTask(){
    //exec code here

  }
}

In your Activity class, each time you create a Fragment, add it to a List too. When the event occurs, call all Fragments.

public class MyActivity extends Activity{
  List<myFragment> mFragmentList = new ArrayList<MyFragment>();

  public void addFragment(MyFragment fragment){
    mFragmentList.add(fragment);
  }

  public void onEvent(){
    for(MyFragment fragment:mFragmentList){
      fragment.doTask();
    }
  }

}

Note: If you don’t have that many Fragments, this solution can be a overkill.