java昨天今天判断

Calendar today = Calendar.getInstance();
		Calendar old = Calendar.getInstance();

                    //此处的isEver everType startTime  createDate为pojo的属性 
                if (("Y".equals(isEver) && everType == 2) || startTime == null) {
			old.setTime(createdDate);
		} else {
			old.setTime(startTime);
		}
                //此处好像是去除0 
                today.set(Calendar.HOUR, 0);
		today.set(Calendar.MINUTE, 0);
		today.set(Calendar.SECOND, 0);
		old.set(Calendar.HOUR, 0);
		old.set(Calendar.MINUTE, 0);
		old.set(Calendar.SECOND, 0);
                //老的时间减去今天的时间
                long intervalMilli = old.getTimeInMillis() - today.getTimeInMillis();
		int xcts = (int) (intervalMilli / (24 * 60 * 60 * 1000));
		// -2:前天 -1：昨天 0：今天 1：明天 2：后天， out：显示日期
		if (xcts >= -2 && xcts <= 2) {
			return String.valueOf(xcts);
		} else {
			return "out";
		}