Java中的 DayOfWeek adjustInto() 方法及示例

Java .time.DayOfWeek的adjustInto()方法是Java中的一个内置函数，它接受一个指定日期的 Temporal 对象并返回一个与输入相同的可观察类型的新 Temporal 对象，其中星期更改为与指定的 DayOfWeek 常量相同。请注意，此方法在周一至周日一周内向前或向后调整。

方法声明：

public Temporal adjustInto(Temporal temporal)

句法：

Temporal newLocalDate = DayOfWeek.ANYWEEKDAY.adjustInto(Temporal temporal)

参数：此方法将时间作为参数，其中：

temporal –是要调整的指定日期。

ANYWEEKDAY –是要调整日期的指定日期，例如，MONDAY、TUESDAY 等。

newLocalDate –是修改日期。

返回值：该函数返回一个调整后的 Temporal 对象，它是根据指定的星期几调整的日期。

下面的程序说明了上述方法：
方案一：

import java.time.*;
import java.time.DayOfWeek;
import java.time.temporal.Temporal;
  
class DayOfWeekExample {
    public static void main(String[] args)
    {
        // Set a Local Date whose day is found
        LocalDate localDate1
            = LocalDate.of(1947, Month.AUGUST, 15);
  
        // Find the day from the Local Date
        DayOfWeek dayOfWeek1
            = DayOfWeek.from(localDate1);
  
        // Printing the Local Date
        System.out.println(localDate1
                           + " which is "
                           + dayOfWeek1.name());
  
        // Adjust the Date to Monday from Friday
        Temporal localDate2
            = DayOfWeek.MONDAY
                  .adjustInto(localDate1);
  
        // Find the day from the new Local date
        DayOfWeek dayOfWeek2
            = DayOfWeek.from(localDate2);
  
        // Printing the new Local Date
        System.out.println(localDate2
                           + " which is "
                           + dayOfWeek2.name());
    }
}

输出：

1947-08-15 which is FRIDAY
1947-08-11 which is MONDAY

方案二：

import java.time.*;
import java.time.DayOfWeek;
import java.time.temporal.Temporal;
  
class DayOfWeekExample {
    public static void main(String[] args)
    {
        // Set a Local Date whose day is found
        LocalDate localDate1
            = LocalDate.of(2019, Month.MARCH, 18);
  
        // Find the day from the Local Date
        DayOfWeek dayOfWeek1
            = DayOfWeek.from(localDate1);
  
        // Printing the Local Date
        System.out.println(localDate1
                           + " which is "
                           + dayOfWeek1.name());
  
        // Adjust the Date to Wednesday from Monday
        Temporal localDate2
            = DayOfWeek.WEDNESDAY
                  .adjustInto(localDate1);
  
        // Find the day from the new Local date
        DayOfWeek dayOfWeek2
            = DayOfWeek.from(localDate2);
  
        // Printing the new Local Date
        System.out.println(localDate2
                           + " which is "
                           + dayOfWeek2.name());
    }
}

输出：

2019-03-18 which is MONDAY
2019-03-20 which is WEDNESDAY

参考： https: Java/time/DayOfWeek.html#adjustInto-java.time.temporal.Temporal-