Java的.time.YearMonth类在Java中
Java YearMonth 类提供“年-月”格式的输出。这个类是一个不可变的类，这意味着它定义的对象一旦创建就永远不会改变它们的值。任何从年和月派生的字段，如季度，通常都可以获得。此类不存储或表示日期、时间或时区。例如，它不会显示值“November-2006-12:00”，而是会显示“2007-11”。它继承了thing类并实现了Comparable接口。
Java YearMonth 类实现了 Temporal、TemporalAdjuster、Comparable
public final class YearMonth extends Object
implements Temporal, TemporalAdjuster, Comparable
| Method | Description |
|---|---|
| adjustInto(Temporal temporal) | This method adjusts the specified temporal object to have this year-month. |
| atDay(int dayOfMonth) | This method combines this year-month with a day-of-month to create a LocalDate. |
| atEndOfMonth() | This method returns a LocalDate at the end of the month. |
| compareTo(YearMonth other) | This method compares this year-month to another year-month. |
| equals(Object obj) | This method checks if this year-month is equal to another year-month. |
| format(DateTimeFormatter formatter) | This method Formats this year-month using the specified formatter. |
| from(TemporalAccessor temporal) | This method obtains an instance of YearMonth from a temporal object. |
| get(TemporalField field) | This method gets the value of the specified field from this year-month as an int. |
| getLong(TemporalField field) | This method gets the value of the specified field from this year-month as along. |
| getMonth() | This method gets the month-of-year field using the Month enum. |
| getMonthValue() | This method gets the month-of-year field from 1 to 12. |
| getYear() | This method gets the year field. |
| hashCode() | A hash code for this year-month. |
| isAfter(YearMonth other) | This method checks if this year-month is after the specified year-month. |
| isBefore(YearMonth other) | This method checks if this year-month is before the specified year-month. |
| isLeapYear() | This method checks if the year is a leap year, according to the ISO proleptic calendar system rules. |
| isSupported(TemporalField field) | This method checks if the specified field is supported. |
| isSupported(TemporalUnit unit) | This method checks if the specified unit is supported. |
| isValidDay(int dayOfMonth) | This method checks if the day-of-month is valid for this year-month. |
| lengthOfMonth() | This method returns the length of the month, taking account of the year. |
| lengthOfYear() | This method returns the length of the year. |
| minus(long amountToSubtract, TemporalUnit unit) | This method returns a copy of this year-month with the specified amount subtracted. |
| minus(TemporalAmount amountToSubtract) | This method returns a copy of this year-month with the specified amount subtracted. |
| minusMonths(long monthsToSubtract) | This method returns a copy of this YearMonth with the specified number of months subtracted. |
| minusYears(long yearsToSubtract) | This method returns a copy of this YearMonth with the specified number of years subtracted. |
| now() | This method obtains the current year-month from the system clock in the default time-zone. |
| now(Clock clock) | This method obtains the current year-month from the specified clock. |
| now(ZoneId zone) | This method obtains the current year-month from the system clock in the specified time-zone. |
| of(int year, int month) | This method obtains an instance of YearMonth from a year and month. |
| of(int year, Month month) | This method obtains an instance of YearMonth from a year and month. |
| parse(CharSequence text) | This method obtains an instance of YearMonth from a text string such as 2007-12. |
| parse(CharSequence text, DateTimeFormatter formatter) | This method obtains an instance of YearMonth from a text string using a specific formatter. |
| plus(long amountToAdd, TemporalUnit unit) | This method returns a copy of this year-month with the specified amount added. |
| plus(TemporalAmount amountToAdd) | This method returns a copy of this year-month with the specified amount added. |
| plusMonths(long monthsToAdd) | This method returns a copy of this YearMonth with the specified number of months added. |
| plusYears(long yearsToAdd) | This method returns a copy of this YearMonth with the specified number of years added. |
| query(TemporalQuery | This method queries this year-month using the specified query. |
| range(TemporalField field) | This method gets the range of valid values for the specified field. |
| toString() | This method outputs this year-month as a String, such as 2007-12. |
| until(Temporal endExclusive, TemporalUnit unit) | This method calculates the amount of time until another year-month in terms of the specified unit. |
| with(TemporalAdjuster adjuster) | This method returns an adjusted copy of this year-month. |
| with(TemporalField field, long newValue) | This method returns a copy of this year-month with the specified field set to a new value. |
| withMonth(int month) | This method returns a copy of this YearMonth with the month-of-year altered. |
| withYear(int year) | This method returns a copy of this YearMonth with the year altered. |
下面是Java YearMonth 类的一些方法的实现：
1. plus()：返回添加了所需数量的该年月的副本。
Java
// plus() Method implementation
import java.time.*;
public class Example {
public static void main(String[] args)
{
YearMonth obj1 = YearMonth.now();
// plus(Period.ofYears(int)) will add
// no.of years to the existing year
YearMonth obj2 = obj1.plus(Period.ofYears(0));
System.out.println(obj2);
}
}Java
// minus() method implementation
import java.time.*;
public class Example {
public static void main(String[] args)
{
YearMonth obj1 = YearMonth.now();
//.minus(Period.ofYears(int)) will subtract
// no. ofyears from the existing year
YearMonth obj2 = obj1.minus(Period.ofYears(3));
System.out.println(obj2);
}
}输出
2021-022. 减（）：返回减去所需数量的这一年月的副本。
Java
// minus() method implementation
import java.time.*;
public class Example {
public static void main(String[] args)
{
YearMonth obj1 = YearMonth.now();
//.minus(Period.ofYears(int)) will subtract
// no. ofyears from the existing year
YearMonth obj2 = obj1.minus(Period.ofYears(3));
System.out.println(obj2);
}
}
输出
2018-02