Add the response string into a List<String>
like this
List<String> responseList = new ArrayList<String>();
for (int i = 0; i < json.length(); i++) {
final JSONObject e = json.getJSONObject(i);
String name = e.getString("area");
responseList.add(name);
}
Now, you can set the response list to AutoCompleteTextView like this
ArrayAdapter<String> adapter = new ArrayAdapter<String>(this,
android.R.layout.simple_dropdown_item_1line, responseList);
AutoCompleteTextView textView = (AutoCompleteTextView)
findViewById(R.id.autoCompleteTextView1);
textView.setAdapter(adapter);