Tima Tima - 10 days ago 6
Android Question

notifyDataSetChanged example

I'm trying to use in my

Android Application
the
notifyDataSetChanged()
method for an
ArrayAdapter
but it doesn't work for me.

I found as answer here, that
notifyDataSetChanged()
should run in the main thread, but there was no example for that.

Could anybody send an example or at least a link?!

Answer

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:

  1. Use the functions of the ArrayAdapter to modify the underlying List (add(), insert(), remove(), clear(), etc.)
  2. Re-create the ArrayAdapter with the new List data. (Uses a lot of resources and garbage collection.)
  3. Create your own class derived from BaseAdapter and ListAdapter that allows changing of the underlying List data structure.
  4. Use the notifyDataSetChanged() every time the list is updated. To call it on the UI-Thread, use the runOnUiThread() of Activity. Then, notifyDataSetChanged() will work.