获取某一天的前一天的日期

String registerTime=“2017-06-05”;

Calendar c = Calendar.getInstance(); 

Date date = null;
try {
date = new SimpleDateFormat("yy-MM-dd").parse(registerTime);
} catch (ParseException e) {
e.printStackTrace();
} 
c.setTime(date); 
int day=c.get(Calendar.DATE); 
c.set(Calendar.DATE,day-1); 
String lastregisterTime = new SimpleDateFormat("yyyy-MM-dd").format(c.getTime()); 
System.out.println(lastregisterTime);