ArrayList return size() zero

mNewList return size() zero but it contains data that it show in ListView, mListData.getContacts(); returns ArrayList fetched from server via internet but its not a problem as i written before it shows data in ListView.

ArrayList<String> mNewList = new ArrayList<String>();
mNewList = mListData.getContacts();
adapter = new ArrayAdapter<String>(MainActivity.this, 
android.R.layout.simple_list_item_1, mNewList);
mList.setAdapter(adapter);

via Chebli Mohamed