How to auto refresh the contents from custom adapter when its data depends on another class?

Question

I am trying to change the view from one class when the data changes in another class using notifyDataSetChanged() on custom adapter.

Class FragmentOne starts thread where listItems are added.

Then I am using class FragmentTwo and getting those listItems and updating my view.

My code---

Class FragmentOne

static ArrayList<String> listItems = null;

private class MonitorLogThread extends Thread
{
    BufferedReader br;

    @Override
    public void run() {

while(((line=br.readLine()) != null) && !this.isInterrupted()){
   listItems.add(line);
}
 }

Class FragmentTwo

private BBLogListAdapter mBBLogListAdapter;
ArrayList<String> receiptlist;

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

     if(receiptlist == null)
        receiptlist = new ArrayList<String>();
    else
        receiptlist.clear();

    // Initializes list view adapter.
    mBBLogListAdapter = new BBLogListAdapter();
    setListAdapter(mBBLogListAdapter);

    mBBLogListAdapter.updateReceiptsList(FragmentOne.listItems);

    mBBLogListAdapter.notifyDataSetChanged();
 }

        // Custom Adapter
        private class BBLogListAdapter extends BaseAdapter {
             //Code to set view dynamically according to data in adapter
             public void updateReceiptsList(ArrayList<String> newlist) {
             receiptlist.clear();
             receiptlist.addAll(newlist);
        }

        //Some more code..
      }
} 

So, currently I am using method updateReceiptsList in the method onResume() to update the contents. This only updates when we resume the activity.

But I want to auto refresh the contents while in this activity according to data change from another activity.

Answer 1

Grab a hold of your adapter object and create a static method in "FragmentTwo",

public static void notifyDataChanged(){
  if(mBBLogListAdapter != null){
       mBBLogListAdapter.updateReceiptsList(FragmentOne.listItems);
       mBBLogListAdapter.notifyDataSetChanged();
  }
}

Whenever your data changes in your thread call this static method.

static ArrayList<String> listItems = null;

private class MonitorLogThread extends Thread
{
  BufferedReader br;

 @Override
 public void run() {

while(((line=br.readLine()) != null) && !this.isInterrupted()){
 listItems.add(line);

 FragmentTwo.notifyDataChanged();
 }
}

Note that, you need to use the same adapter object that you used to setAdapter in FragmentTwo's onResume

setListAdapter(mBBLogListAdapter);

PS: A cleaner alternative would be to use a listener on "FragmentTwo" that listens to any data changes on "FragmentOne". See here for implementation details - http://docs.oracle.com/javase/tutorial/uiswing/events/actionlistener.html

Hope this helps.