Date类型计算天数与比较大小

一、计算天数

long startDateTime = topicTask.getTaskStartDate().getTime();
long endDateTime = topicTask.getTaskEndDate().getTime();
long dayTime = (endDateTime - startDateTime) / (1000 * 3600 * 24);

二、比较大小java中

int i = workHour.getStartDate().compareTo(workHour.getEndDate());

如果startDate大于endDate则为1小于则为负数等于则为0

比较大小mybatis中

    and date_format(topic_start_date,'%y%m%d') ">>= date_format(#{topicStartDate},'%y%m%d')