Java取某个时间为标杆往前或往后推n小时

Java取某个时间为标杆往前或往后推n小时

SimpleDateFormat sdf = new SimpleDateFormat("yyyy-MM-dd HH:mm:ss");
String end = “时间”;
try {Date start = sdf.parse(end);Calendar calendar = new GregorianCalendar();calendar.setTime(start);calendar.add(calendar.HOUR,-1);//+为往后-为往前start = Time();String startTime = sdf.format(start);} catch (ParseException e) {e.printStackTrace();}