Pomis

public class MainActivity extends AppCompatActivity {
    ... ... ...
    public void addMessage(String messageText, String messageSender, int messageId) {
        MessageModel messageModel =
                new MessageModel(messageText, messageSender, messageId);
        arrayList.add(messageModel);
        adapter.notifyDataSetChanged();
    }
}

Pomis

    static String convertStreamToString(InputStream is) {
        BufferedReader reader = new BufferedReader(new InputStreamReader(is));
        StringBuilder sb = new StringBuilder();

        String line = null;
        try {
            while ((line = reader.readLine()) != null) {
                sb.append(line + "\n");
            }
        } catch (IOException e) {