How to update ListView after onResume from other activity?

Question

Im trying to create an application that enable user to create event, then invite participant. So when user go to \"add participant\" page, after entering all information, im

Answer 1

First, your adapter.notifyDataSetChanged() right before setListAdapter(adapter); in the onCreate() method is useless because the list isn't aware of the data unless you call setListAdapter().

So here is the easy way in you class EventPage :

@Override
protected void onResume()
{
    super.onResume();

    if (getListView() != null)
    {
        updateData();
    }
}

private void updateData()
{
    SimpleAdapter adapter = new SimpleAdapter(EventPage.this, 
                                              controller.getAllFriends(queryValues), 
                                              R.layout.view_friend_entry, 
                                              new String[] {"friendId", "friendName" },
                                              new int[] { R.id.friendId, R.id.friendName });
    setListAdapter(adapter);
}

So here, we basically refresh the data every time onResume() is called.

If you want to do it only after adding a new item, then you must use onActivityResult() instead on onResume():

private static final int ADD_PARTICIPANT = 123;// the unique code to start the add participant activity 

@Override
protected void onActivityResult(int requestCode, int resultCode, Intent data)
{
    super.onActivityResult(requestCode, resultCode, data);

    if (requestCode == ADD_PARTICIPANT && resultCode == Activity.RESULT_OK)
    {
        updateData();
    }
}

private void updateData()
{
    SimpleAdapter adapter = new SimpleAdapter(EventPage.this, 
                                              controller.getAllFriends(queryValues), 
                                              R.layout.view_friend_entry, 
                                              new String[] {"friendId", "friendName" },
                                              new int[] { R.id.friendId, R.id.friendName });
    setListAdapter(adapter);
}

Now, simply replace in your onCreate() method the startActivity by startActivityForResult(objIndent, ADD_PARTICIPANT);

Lastly, in your AddParticipant activity, add setResult(Activity.RESULT_OK); just before onFinish();