notifyDataSetChanged example
For an ArrayAdapter
, notifyDataSetChanged
only works if you use the add()
, insert()
, remove()
, and clear()
on the Adapter.
When an ArrayAdapter
is constructed, it holds the reference for the List
that was passed in. If you were to pass in a List
that was a member of an Activity, and change that Activity member later, the ArrayAdapter
is still holding a reference to the original List
. The Adapter does not know you changed the List
in the Activity.
Your choices are:
- Use the functions of the
ArrayAdapter
to modify the underlying List (add()
,insert()
,remove()
,clear()
, etc.) - Re-create the
ArrayAdapter
with the newList
data. (Uses a lot of resources and garbage collection.) - Create your own class derived from
BaseAdapter
andListAdapter
that allows changing of the underlyingList
data structure. - Use the
notifyDataSetChanged()
every time the list is updated. To call it on the UI-Thread, use therunOnUiThread()
ofActivity
.Then,notifyDataSetChanged()
will work.
You can use the runOnUiThread()
method as follows. If you're not using a ListActivity
, just adapt the code to get a reference to your ArrayAdapter
.
final ArrayAdapter adapter = ((ArrayAdapter)getListAdapter());runOnUiThread(new Runnable() { public void run() { adapter.notifyDataSetChanged(); }});
I recently wrote on this topic, though this post it old, I thought it will be helpful to someone who wants to know how to implement BaseAdapter.notifyDataSetChanged()
step by step and in a correct way.
Please follow How to correctly implement BaseAdapter.notifyDataSetChanged() in Android or the newer blog BaseAdapter.notifyDataSetChanged().