How to run a Runnable thread in Android at defined intervals?

Question

I developed an application to display some text at defined intervals in the Android emulator screen. I am using the Handler class. Here is a snippet from my cod

Answer 1

Handler handler=new Handler();
Runnable r = new Runnable(){
    public void run() {
        tv.append("Hello World");                       
        handler.postDelayed(r, 1000);
    }
}; 
handler.post(r);