日本祝日用java计算

以下是一个使用Java计算日本祝日的示例代码：

import java.time.LocalDate;
import java.time.Month;

public class JapaneseHolidays {
    
    public static void main(String[] args) {
        LocalDate date = LocalDate.of(2021, Month.JANUARY, 1);
        for (int i = 0; i < 12; i++) {
            System.out.println(getHolidayName(date));
            date = date.plusMonths(1);
        }
    }

    public static String getHolidayName(LocalDate date) {
        int year = date.getYear();
        Month month = date.getMonth();
        int day = date.getDayOfMonth();

        switch (month) {
            case JANUARY:
                if (day == 1) {
                    return "元日";
                } else if (year >= 2000 && day == 2) {
                    return "振替休日";
                }
                break;
            case FEBRUARY:
                if (day == 11) {
                    return "建国記念の日";
                } else if (year >= 2000 && day == 12) {
                    return "振替休日";
                }
                break;
            case MARCH:
                if (day == getVernalEquinoxDay(year)) {
                    return "春分の日";
                }
                break;
            case APRIL:
                if (day == 29) {
                    return "昭和の日";
                } else if (year >= 2000 && day == 30) {
                    return "振替休日";
                }
                break;
            case MAY:
                if (day == 3) {
                    return "憲法記念日";
                } else if (day == 4) {
                    return "みどりの日";
                } else if (day == 5) {
                    return "こどもの日";
                } else if (year >= 2000 && day == 6 && date.getDayOfWeek().getValue() == 1) {
                    return "振替休日";
                }
                break;
            case JULY:
                if (day == 23) {
                    return "海の日";
                } else if (year >= 2020 && day == 24) {
                    return "スポーツの日";
                } else if (year >= 2000 && day == 20 && year != 2020) {
                    return "海の日";
                } else if (year >= 2000 && day == 22 && date.getDayOfWeek().getValue() == 1 && year != 2020) {
                    return "振替休日";
                }
                break;
            case AUGUST:
                if (day == 8) {
                    return "山の日";
                } else if (year >= 2016 && day == 11) {
                    return "山の日";
                } else if (year >= 2000 && day == 10 && date.getDayOfWeek().getValue() == 1 && year != 2020 && year != 2016) {
                    return "振替休日";
                }
                break;
            case SEPTEMBER:
                if (day == getAutumnalEquinoxDay(year)) {
                    return "秋分の日";
                }
                break;
            case OCTOBER:
                if (day == 11) {
                    return "体育の日";
                } else if (year >= 2000 && day == 12) {
                    return "振替休日";
                }
                break;
            case NOVEMBER:
                if (day == 3) {
                    return "文化の日";
                } else if (day == 23) {
                    return "勤労感謝の日";
                } else if (year >= 2000 && day == 4 && date.getDayOfWeek().getValue() == 1) {
                    return "振替休日";
                }
                break;
            case DECEMBER:
                if (day == 23) {
                    return "天皇誕生日";
                } else if (year >= 1989 && month == Month.DECEMBER && day == 31) {
                    return "年末休暇";
                }
                break;
        }

        return "";
    }

    public static int getVernalEquinoxDay(int year) {
        if (year <= 1947) {
            return 0;
        } else if (year <= 1979) {
            return (int) (20.8357 + (0.242194 * (year - 1980)) - ((year - 1983) / 4));
        } else if (year <= 2099) {
            return (int) (20.8431 + (0.242194 * (year - 1980)) - ((year - 1980) / 4));
        } else if (year <= 2150) {
            return (int) (21.851 + (0.242194 * (year - 1980)) - ((year - 1980) / 4));
        } else {
            return 0;
        }
    }

    public static int getAutumnalEquinoxDay(int year) {
        if (year <= 1947) {
            return 0;
        } else if (year <= 1979) {
            return (int) (23.2588 + (0.242194 * (year - 1980)) - ((year - 1983) / 4));
        } else if (year <= 2099) {
            return (int) (23.2488 + (0.242194 * (year - 1980)) - ((year - 1980) / 4));
        } else if (year <= 2150) {
            return (int) (24.2488 + (0.242194 * (year - 1980)) - ((year - 1980) / 4));
        } else {
            return 0;
        }
    }
}

这个代码可以计算从2021年1月1日开始的所有日本祝日，并将它们的名称打印到控制台上。要计算不同年份的祝日，只需更改代码中的年份即可。