have ScrollView scroll down automatically

Hello, I have a chat application, but as it goes along with messages, the user is forced to see all the typed messages from the first one, he should roll the bar to the end to see the last message, I already researched some ways to solve this but I did not find it. the solution I found was this:

      scrollViewObject.postDelayed(new Runnable() {
        @Override
        public void run() {
            scroll.fullScroll(ScrollView.FOCUS_UP);
        }
    }, 600);

but the error. Can someone help me?