Java8 API 时间类MonthDay

MonthDay是一个不变的日期时间对象，代表月和日的组合。其格式是：

–MM-dd(这里开头有两个横杠)，格式不是我们常用的格式：MM-dd。

import java.time.*;
import java.time.format.DateTimeFormatter;
import java.time.temporal.ChronoField;
import java.time.temporal.Temporal;

public class MonthDayTest {

    public static void main(String[] args) {
        LocalDate localDate = LocalDate.of(2020,1,2);

        MonthDay monthDay = MonthDay.now();
        System.out.println("monthDay:"+monthDay);
        Temporal temporal = monthDay.adjustInto(localDate);
        System.out.println("LocalDate:"+localDate);
        System.out.println("adjustInto:"+temporal);
        System.out.println("-----------------------------------------");

        LocalDate atYear = monthDay.atYear(2016);
        System.out.println("atYear:"+atYear);
        System.out.println("-----------------------------------------");


        //compareTo注意点：比较的是两个年月中间查的月份数，并不是大于=1 相等=0 小于=-1
        MonthDay monthDay2 = MonthDay.of(10, 10);
        int i = monthDay.compareTo(monthDay2);
        System.out.println("monthDay.compareTo(monthDay2) :"+ i);
        int i2 = monthDay2.compareTo(monthDay);
        System.out.println("monthDay2.compareTo(monthDay) :"+ i2);
        System.out.println("-----------------------------------------");

        //equals
        System.out.println("monthDay.equals(monthDay2) :"+ monthDay.equals(monthDay2));
        MonthDay monthDay3 = MonthDay.of(12, 7);
        System.out.println("monthDay.equals(monthDay3) :"+ monthDay.equals(monthDay3));
        System.out.println("-----------------------------------------");

        //format
        DateTimeFormatter dtf = DateTimeFormatter.ofPattern("M月d日");
        String format = monthDay.format(dtf);
        System.out.println("format :"+ format);
        System.out.println("-----------------------------------------");

        MonthDay from = MonthDay.from(localDate);
        System.out.println("from :"+ from);
        System.out.println("-----------------------------------------");

        //get
        System.out.println("get Year :"+ monthDay.get(ChronoField.MONTH_OF_YEAR));
        //get MonthDay 不支持 monthDay.get(ChronoField.MICRO_OF_DAY)
        //java.time.temporal.UnsupportedTemporalTypeException: Unsupported field: MicroOfDay
        //System.out.println("get Month :"+ monthDay.get(ChronoField.MICRO_OF_DAY));
        System.out.println("-----------------------------------------");

        //getLong
        System.out.println("getLong :"+ monthDay.getLong(ChronoField.MONTH_OF_YEAR));
        System.out.println("getLong :"+ monthDay.getLong(ChronoField.DAY_OF_MONTH));
        //monthDay 不支持 getLong(ChronoField.SECOND_OF_DAY)
        //java.time.temporal.UnsupportedTemporalTypeException: Unsupported field: SecondOfDay
        //System.out.println("getLong :"+ monthDay.getLong(ChronoField.SECOND_OF_DAY));
        System.out.println("-----------------------------------------");

        //getMonth
        System.out.println("getMonth :"+ monthDay.getMonth());
        System.out.println("-----------------------------------------");

        //isValidDay
        //MonthDay.of(2021, 6) 报错：java.time.DateTimeException: Invalid value for MonthOfYear: 2021
        MonthDay monthDay4 = MonthDay.of(12, 6);
        boolean validDay = monthDay4.isValidYear(2016);
        System.out.println("isValidDay :"+ validDay);
        boolean validDay2 = monthDay4.isValidYear(2017);
        System.out.println("isValidDay :"+ validDay2);
        System.out.println("-----------------------------------------");

        //parse 支持的默认格式:--MM-dd
        System.out.println("parse :"+ MonthDay.parse("--06-06"));
        //parse 不是默认格式:yyyy-MM，则报错
        //System.out.println("parse :"+ YearMonth.parse("2020-6"));
        System.out.println("parse :"+ MonthDay.parse("7月31日",dtf));
        System.out.println("-----------------------------------------");

        //range
        System.out.println("range Month:"+ monthDay.range(ChronoField.MONTH_OF_YEAR));
        System.out.println("-----------------------------------------");


        //with
        System.out.println("withYear :"+monthDay.with(Month.MARCH));
        System.out.println("-----------------------------------------");
    }
}

输出：

monthDay:--07-16
LocalDate:2020-01-02
adjustInto:2020-07-16
-----------------------------------------
atYear:2016-07-16
-----------------------------------------
monthDay.compareTo(monthDay2) :-3
monthDay2.compareTo(monthDay) :3
-----------------------------------------
monthDay.equals(monthDay2) :false
monthDay.equals(monthDay3) :false
-----------------------------------------
format :7月16日
-----------------------------------------
from :--01-02
-----------------------------------------
get Year :7
-----------------------------------------
getLong :7
getLong :16
-----------------------------------------
getMonth :JULY
-----------------------------------------
isValidDay :true
isValidDay :true
-----------------------------------------
parse :--06-06
parse :--07-31
-----------------------------------------
range Month:1 - 12
-----------------------------------------
withYear :--03-16
-----------------------------------------