Java利用LocalDate类实现日历设计

LocalDate.now() // 2022-07-01

LocalDate.of(1999, 1, 1)

LocalDate newYearsEve = LocalDate.of(1999, 1, 1);

int year = newYearsEve.getYear(); // 1999
int month = newYearsEve.getMonthValue(); // 1
int day = newYeaersEve.getDayOfMonth(); // 1

LocalDate aThousandDaysLater = newYearsEve.plusDays(1000);
year = aThousandDaysLater.getYear();  // 2002
month = aThousandDaysLater.getMonthValue();  // 09
day = aThousandDaysLater.getDayOfMonth();  // 26

`LocalDate date = LocalDate.now();`

int month = date.getMonthValue();
int today = date.getDayOfMonth();

date = date.minusDays(today - 1);  // 设置为当月的第一天
DayOfWeek weekday = date.getDayOfWeek();
int value = weekday.getValue();  // 1 = Monday    7 = Sunday

System.out.println("Mon Tue Wed Thu Fri Sat Sun");
for (int i = 1; i < value; i++)
    System.out.print("    ");

while (date.getMonthValue() == month) {
    System.out.printf("%3D", date.getDayOfMonth());
    if (date.getDayOfMonth() == today)
        System.out.print("*");
    else
        System.out.print(" ");
    date = date.plusDays(1);
    if (date.getDayOfWeek().getValue() == 1)
        System.out.println();
}

import java.time.DayOfWeek;
import java.time.LocalDate;


public class 制作日历 {
    public static void main(String[] args) {
        // 创建一个日期对象，并进行初始化
        LocalDate date = LocalDate.now();
        System.out.println(date);
        // 获取当前月份和日期
        int month = date.getMonthValue();
        int today = date.getDayOfMonth();

        // 将date设置为这个月的第一天，并得到这一天为星期几
        date = date.minusDays(today - 1);
        // 设置为DayOfWeek类型的对象。调用这个对象的getValue方法来得到星期几的一个数值
        DayOfWeek weekday = date.getDayOfWeek();
        int value = weekday.getValue();  // 1 = Monday    7 = Sunday

        System.out.println("Mon Tue Wed Thu Fri Sat Sun");
        for (int i = 1; i < value; i++)
            System.out.print("    ");

        while (date.getMonthValue() == month) {
            System.out.printf("%3d", date.getDayOfMonth());
            if (date.getDayOfMonth() == today)
                System.out.print("*");
            else
                System.out.print(" ");
            date = date.plusDays(1);
            if (date.getDayOfWeek().getValue() == 1)
                System.out.println();
        }
        if (date.getDayOfWeek().getValue() != 1)
            System.out.println();
    }
}

static LocalDate now()
 //构造一个表示当前日期的对象

static LocalDate of(int year, int month, int day)
//构造一个表示给定日期的对象

int getYear()
int getMonthValue()
int getDayOfMonth()
//得到当前日期的年、月和日。

DayOfWeek getDayOfWeek
//得到当前日期是星期几，作为DayOfWeek类的一个实例返回。调用getValue来得到1~7之间的一个数，表示这是星期几，1表示星期一，7表示星期日

LocalDate plusDays(int n)
LocalDate minusDays(int n)
//生成当前日期之后或之前n天的日期