public class MainActivity extends AppCompatActivity {
    private static final String TAG = MainActivity.class.getSimpleName();
    private Session session;
    private SignalMessageAdapter messageHistory;
    private EditText messageEditTextView;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);

        messageEditTextView = findViewById(R.id.message_edit_text);
        ListView messageHistoryListView = findViewById(R.id.message_history_list_view);

        // Attach data source to message history
        messageHistory = new SignalMessageAdapter(this);
        messageHistoryListView.setAdapter(messageHistory);

        messageEditTextView.setEnabled(false);

        session = new Session.Builder(this, VonageVideoSDKConfig.APP_ID, VonageVideoSDKConfig.SESSION_ID).build();
        session.setSessionListener(sessionListener);
        session.setSignalListener(signalListener);
        session.connect(VonageVideoSDKConfig.TOKEN);

        messageEditTextView.setOnEditorActionListener(new TextView.OnEditorActionListener() {
            @Override
            public boolean onEditorAction(TextView v, int actionId, KeyEvent event) {
                if (actionId == EditorInfo.IME_ACTION_DONE) {
                    InputMethodManager inputMethodManager = (InputMethodManager) v.getContext().getSystemService(Context.INPUT_METHOD_SERVICE);
                    inputMethodManager.hideSoftInputFromWindow(v.getWindowToken(), 0);
                    sendMessage();
                    return true;
                }
                return false;
            }
        });
    }

    private void sendMessage() {
        Log.d(TAG, "Send Message");
        String data = messageEditTextView.getText().toString();
        session.sendSignal("msg", data);

        SignalMessage message = new SignalMessage(data);
        messageHistory.add(message);

        messageEditTextView.setText("");
    }
    
    private final Session.SessionListener sessionListener = new Session.SessionListener() {
        @Override
        public void onConnected(Session session) {
            messageEditTextView.setEnabled(true);
        }
        @Override
        public void onDisconnected(Session session) {
            messageEditTextView.setEnabled(false);
        }

        @Override
        public void onError(Session session, OpentokError opentokError) {
            Log.i(TAG,"Session error: " + opentokError.getMessage());
        }

        @Override
        public void onStreamReceived(Session session, Stream stream) {}

        @Override
        public void onStreamDropped(Session session, Stream stream) {}
    };

    private final Session.SignalListener signalListener = new Session.SignalListener() {
        @Override
        public void onSignalReceived(Session session, String type, String data, Connection connection) {
            if (!connection.equals(session.getConnection()) && (type != null && type.equals("msg"))) {
                SignalMessage message = new SignalMessage(data, true);
                messageHistory.add(message);
            }
        }
    };
}