How to refresh a ListView from a BroadcastReceiver?

Question

If I call notifyDataSetChanged() on the custom adapter associated to my ListView, all the views should refresh themself (getView() will be called). Now I have a BroadcastReceiver that is listening to an event. When the event fires, the ListView must be refreshed. How can I achieve this? Thanks!

Answer 1

If you refresh listview from receiver you'll have code like this:

BroadcastReceiver br;
public final static String BROADCAST_ACTION = "BROADCAST_ACTION";
br = new BroadcastReceiver() {
public void onReceive(Context context, Intent intent) {
//code refreshing...
}
};
IntentFilter intFilt = new IntentFilter(BROADCAST_ACTION);
registerReceiver(br, intFilt);

And you call it with code:

Intent intent = new Intent(BROADCAST_ACTION);
sendBroadcast(intent);

If you need the refresh to be another action you just need to add (after action):

Intent intent = new Intent(BROADCAST_ACTION);
sendBroadcast(intent);

Answer 2

As requested, please see the sample code below:

public interface OnDataUpdateListener {
    void onDataAvailable(ArrayList<String> newDataList);
}

public class MyTestReceiver extends BroadcastReceiver {
    public static final String DATA_LIST = "DATA_LIST";
    private OnDataUpdateListener mDataUpdateListener = null;
    public MyTestReceiver(OnDataUpdateListener dataUpdateListener) {
        mDataUpdateListener = dataUpdateListener;
    }

    @Override
    public void onReceive(Context ctx, Intent intent) {
        // assuming data is available in the delivered intent
        ArrayList<String> dataList = intent.getSerializableExtra(DATA_LIST);
        if (null != mDataUpdateListener) {
            mDataUpdateListener.onDataAvailable(dataList);
        }
    }
}

public class MyActivity extends FragmentActivity implements OnDataUpdateListener {
    public static final String ACTION_DATA_UPDATE_READY = "ACTION_DATA_UPDATE_READY";
    private MyTestReceiver mTestReceiver = null;
    private <SomeAdapterClass> mAdapter = null;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        // other required initialization 
        mTestReceiver = new MyTestReceiver(this);
    }

    @Override
    public void onResume() {
        super.onResume();
        if (null != mTestReceiver) {
            registerReceiver(mTestReceiver, new IntentFilter(ACTION_DATA_UPDATE_READY));
        }
    }

    void onDataAvailable(ArrayList<String> newDataList) {
        // assuming you want to replace existing data and not willing to append to existing dataset
        mAdapter.clear();
        mAdapter.addAll(newDataList);
        mAdapter.notifyDataSetChanged();
    }
}

Answer 3

In the code where your data is updated, fire off a message signalling that data has been changed... (You will need access to either the Activity or the Application context to do this)

Intent intent = new Intent("ListViewDataUpdated");
LocalBroadcastManager.getInstance(context.sendBroadcast(intent));

Then just catch the catch the message using the following code in your activity, and tell your ListAdapter to update...

private BroadcastReceiver mMessageReceiver = new BroadcastReceiver() {
          @Override
          public void onReceive(Context context, Intent intent) {
            myListAdapter.notifyDataSetChanged();
           }
        };

@Override
public void onResume(){
  super.onResume();
  LocalBroadcastManager.getInstance(this).registerReceiver(mMessageReceiver, new IntentFilter("ListViewDataUpdated"));
  myListAdapter.notifyDataSetChanged();//in case our data was updated while this activity was paused
}


@Override
protected void onPause() {
   LocalBroadcastManager.getInstance(this).unregisterReceiver(mMessageReceiver);
   super.onPause();
}

Credit: adapted from Vogella

Answer 4

LocalBroadcastManager.getInstance(context.sendBroadcast(intent));

change to

LocalBroadcastManager.getInstance(context).sendBroadcast(intent);

I might be wrong but it works for me...