Detailed usage of LocalDateTime

 有时候,We need date calculations,Such as moving based on the current dateXWhat time is the day,Or move on a specified day basisXWhat time is the day,等等..

public static void main(String[] args) {
        DateDemo.nowDateMove(3);
        DateDemo.unKnownDateMove(2016,12,12,6);
    }

    public static void nowDateMove(int num) {
        //获取当前日期
        LocalDate ld = LocalDate.now();
        //The number of days to movenum,Can be an integer or a negative number
        LocalDate ll = ld.plusDays(num);
        System.out.println("今天是： " + ld + "------再过" + num + "天是：" + ll);
    }

    public static void unKnownDateMove(int year, int month, int day, int num) {
        //指定日期
        LocalDate ld = LocalDate.of(year, month, day);
        //The number of days to movenum,Can be an integer or a negative number
        LocalDate ll = ld.plusDays(num);
        System.out.println("The specified date is： " + ld + "------再过" + num + "天是：" + ll);
    }

输出结果

今天是： 2018-12-22------再过3天是：2018-12-25
The specified date is： 2016-12-12------再过6天是：2016-12-18

I had a similar problem before,But the solution is,感觉还是LocalDate简单

1、Step back from the current basis
public class DateMoveUtil {

    /**
     * 日期计算  在当前日期的基础上,推后num天
     * @param num
     * @return
     */
    public String dateFun(int num) {
        Date date = new Date();
        SimpleDateFormat format = new SimpleDateFormat("yyyy-MM-dd");
        Calendar calendar = Calendar.getInstance();
        //Postponed by a certain number of days
        calendar.add(Calendar.DATE,num);
        //返回一个Date对象,表示此Calendar的时间值
        date = calendar.getTime();
        String dateTime = format.format(date);
        return dateTime;
    }
}

2、Go back after a certain date
 SimpleDateFormat format = new SimpleDateFormat("yyyy-MM-dd");
            Date date = format.parse(“2018-10-10”);
            Date date1 = new Date(date.getTime() + 7 * 24 * 60 * 60 * 1000L);
            String time = format.format(date1);

仅供参考,如果大家有好的方法,虚心请教.

（一） LocalDate与LocalDateTime初始化日期,对日期加减.
public static void main(String[] args){
                //获取当前时间(年月日)
              LocalDate localDate=LocalDate.now();
              //格式化日期(DateTimeFormatter是线程安全的,用于localData的时间格式化)
              DateTimeFormatter formatter = DateTimeFormatter.ofPattern("yyyy-MM-dd");
              LocalDate date= LocalDate.parse(localDate.toString(), formatter); //2022-05-23
 
              //增加一年
              LocalDate nextYear = date.plusYears(1); //2023-05-23
              //减少一年
              LocalDate lastYear = date.minusYears(1); //2021-05-23
              //增加一个月
              LocalDate nextMonths= date.plusMonths(1); //2021-06-23
              //增加一天
              LocalDate nextDays= date.plusDays(1); //2021-05-24
 
              //构造指定的年月日
              LocalDate specifiedDate = LocalDate.of(2022, 5, 23);
              //年
              int year = specifiedDate.getYear(); //2022
              //月(这里用到了ChronoField类,有兴趣的可以去了解一下)
              int month1 = specifiedDate.get(ChronoField.MONTH_OF_YEAR); //5
              //日
              int day = specifiedDate.getDayOfMonth(); //23
 
              //创建LocalTime,Only get hours, minutes and seconds
              LocalTime localTime = LocalTime.now();
 
              //创建LocalDateTime,获取年月日时分秒,等于LocalDate+LocalTime
              LocalDateTime localDateTime = LocalDateTime.now();
      }
 （二）Duration 或 ChronoUnit 计算两个时间的间隔
Duration The class calculates the interval

LocalDateTime time = LocalDateTime.parse("2022-06-28T08:41:00");
LocalDateTime time1 = LocalDateTime.parse("2022-06-28T08:42:00");
 
Duration duration = Duration.between(time, time1);
// 相差天数
long datys = duration.toDays();
// 相差小时
long hours = duration.toHours();
// 相差分钟
long minutes = duration.toMinutes();
// 相差秒数
long seconds = duration.getSeconds();
// 相差毫秒
long millis = duration.toMillis();
// difference in nanoseconds
long nanos = duration.toNanos();
 ChronoUnit The class calculates the interval

LocalDateTime time = LocalDateTime.parse("2022-06-28T08:41:00");
LocalDateTime time1 = LocalDateTime.parse("2022-06-28T08:42:00");
 
//相差月
long cuMonths = ChronoUnit.MONTHS.between(time, time1);
//相差天数
long cuDatys = ChronoUnit.DAYS.between(time, time1);
//相差小时
long cuHours = ChronoUnit.HOURS.between(time, time1);
//相差分钟
long cuMinutes = ChronoUnit.MINUTES.between(time, time1);
//相差秒
long cuSeconds = ChronoUnit.SECONDS.between(time, time1);

public static void main(String[] args) {
        DateDemo.nowDateMove(3);
        DateDemo.unKnownDateMove(2016,12,12,6);
    }

    public static void nowDateMove(int num) {
        //获取当前日期
        LocalDate ld = LocalDate.now();
        //The number of days to movenum,Can be an integer or a negative number
        LocalDate ll = ld.plusDays(num);
        System.out.println("今天是： " + ld + "------再过" + num + "天是：" + ll);
    }

    public static void unKnownDateMove(int year, int month, int day, int num) {
        //指定日期
        LocalDate ld = LocalDate.of(year, month, day);
        //The number of days to movenum,Can be an integer or a negative number
        LocalDate ll = ld.plusDays(num);
        System.out.println("The specified date is： " + ld + "------再过" + num + "天是：" + ll);
    }

今天是： 2018-12-22------再过3天是：2018-12-25
The specified date is： 2016-12-12------再过6天是：2016-12-18

1、Step back from the current basis
public class DateMoveUtil {

    /**
     * 日期计算  在当前日期的基础上,推后num天
     * @param num
     * @return
     */
    public String dateFun(int num) {
        Date date = new Date();
        SimpleDateFormat format = new SimpleDateFormat("yyyy-MM-dd");
        Calendar calendar = Calendar.getInstance();
        //Postponed by a certain number of days
        calendar.add(Calendar.DATE,num);
        //返回一个Date对象,表示此Calendar的时间值
        date = calendar.getTime();
        String dateTime = format.format(date);
        return dateTime;
    }
}

2、Go back after a certain date
 SimpleDateFormat format = new SimpleDateFormat("yyyy-MM-dd");
            Date date = format.parse(“2018-10-10”);
            Date date1 = new Date(date.getTime() + 7 * 24 * 60 * 60 * 1000L);
            String time = format.format(date1);