How to converted timestamp string to a date in java

I have a string "1427241600000" and I want it converted to "yyyy-MM-dd" format.

I have tried, but I am not able to parse it, please review the below code

try {
    String str = "1427241600000";
    SimpleDateFormat sf = new  SimpleDateFormat("yyyy-MM-dd");
    Date date =sf.parse(str);
    System.out.println(date);       
} catch (ParseException e) {
    e.printStackTrace();
}

I would like to know where I went wrong.