Using listField to display Json string

I am retrieving a string of values from json url. I have done it like...

for(int i=0;i<totalList;i++){
  String strAlert=jsArrShpList.get(i).toString();
  JSONObject joAlert=new JSONObject(strAlert);
  String shoppingList = joAlert.get("CategoryName").toString();

}

Now i want to add the strings to a list field and i want to get selected index. So plz help me out on how to do it and some sample code will be really helpful...