Open Facebook Session

MainActivity.java

private void openFacebookSession() {
    // Open a Facebook session to get the user's name
    Session.openActiveSession(this, true, new Session.StatusCallback() {

        @Override
        public void call(Session session, SessionState state, Exception exception) {
            if (session.isOpened()) {
                Request.newMeRequest(session, new Request.GraphUserCallback() {

                    // Response Callback
                    @Override
                    public void onCompleted(GraphUser user, Response response) {
                        if (user != null) {
                            TextView welcome = (TextView) findViewById(R.id.welcomeText);
                            welcome.setText("Welcome " + user.getFirstName() + "!");
                        }
                    }
                }).executeAsync();
            }
        }
    });
}