JAVA日期相关操作-编程知识

JAVA日期相关操作

计算两个日期相差的天数

    /*** 计算两个日期相差的  天数* @param smdate String类型初始时间* @param bdate  String类型截至时间* @return Integer*/public static Integer dayCompare(String smdate, String bdate) throws Exception {Date start = sdf.parse(smdate);Date end = sdf.parse(bdate);Calendar cal = Calendar.getInstance();cal.setTime(start);long time1 = cal.getTimeInMillis();cal.setTime(end);long time2 = cal.getTimeInMillis();long between_days = (time2 - time1) / (1000 * 3600 * 24);return Integer.parseInt(String.valueOf(between_days));}

计算两个日期之间的所有日期

   /*** @param startDay 开始时间* @param endDay   结束时间* @return List<String>* @author bigfaceYang* 获取两个日期之间天数* @date 2021/11/11 16:09*/public static List<String> getDays(String startDay, String endDay) throws Exception {List<String> list = new ArrayList<>();Calendar min = Calendar.getInstance();Calendar max = Calendar.getInstance();min.setTime(sdf.parse(startDay));min.set(min.get(Calendar.YEAR), min.get(Calendar.MONTH), min.get(Calendar.DATE), 0, 0, 0);max.setTime(sdf.parse(endDay));max.set(max.get(Calendar.YEAR), max.get(Calendar.MONTH), max.get(Calendar.DATE), 23, 59, 59);Calendar curr = min;while (curr.before(max)) {list.add(sdf.format(curr.getTime()));curr.add(Calendar.DATE, 1);}return list;}

运行结果截图：
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获取当年所有的月份（yyyy-MM）

/*** 获取当年所有月** @return*/public static String[] getYearFullMonth() {String[] array = new String[12];SimpleDateFormat sdf = new SimpleDateFormat("yyyy-MM");Calendar cal = Calendar.getInstance();cal.set(Calendar.YEAR, Integer.parseInt(year.format(new Date())));cal.set(Calendar.MONTH, 0);for (int i = 0; i < 12; i++) {array[i] = sdf.format(cal.getTime());cal.add(Calendar.MONTH, 1);}return array;}

两个月份之间的月份（yyyy-MM）

 /*** @author bigfaceYang*  获取两个日期间年月集合* @param minDate 最小时间 2023-01* @param maxDate 最大时间 2024-05* @return 日期集合 格式为 年-月* @throws Exception*/public static List<String> getMonthBetween(String minDate, String maxDate) throws Exception {ArrayList<String> result = new ArrayList<String>();SimpleDateFormat sdf = new SimpleDateFormat("yyyy-MM");//格式化为年月Calendar min = Calendar.getInstance();Calendar max = Calendar.getInstance();min.setTime(sdf.parse(minDate));min.set(min.get(Calendar.YEAR), min.get(Calendar.MONTH), 1);max.setTime(sdf.parse(maxDate));max.set(max.get(Calendar.YEAR), max.get(Calendar.MONTH), 2);Calendar curr = min;while (curr.before(max)) {result.add(sdf.format(curr.getTime()));curr.add(Calendar.MONTH, 1);}return result;}

在这里插入图片描述

根据年份获取年份下所有月份

/*** 根据年份获取年份下所有月份* @param year* @return*/public static String[] getYearFullMonth(String year){String[] array = new String[12];SimpleDateFormat sdf = new SimpleDateFormat("yyyy-MM");Calendar cal = Calendar.getInstance();cal.set(Calendar.YEAR,Integer.parseInt(year));cal.set(Calendar.MONTH, 0);for(int i=0;i<12;i++){array[i] = sdf.format(cal.getTime());cal.add(Calendar.MONTH, 1);}return array;}

运行结果：

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获取N个月之前的数据

 /*** @author wmw* 获取当前N个月之前或之后的月份     当num=-1 代表前一个月的数据  num=1 代表后一个月的数据* @date 2022/9/14 15:27* @return null*/public static String getLastMonth(Integer num){SimpleDateFormat month = new SimpleDateFormat("yyyy-MM");Calendar c = Calendar.getInstance();c.setTime(new Date());c.add(Calendar.MONTH,num);Date time = c.getTime();return month.format(time);}@SneakyThrowspublic static void main(String[] args) {String lastMonth = getLastMonth(2);System.out.println(lastMonth);//运行结果为：2023-10}