Java 获取某年的第一天和最后一天

在统计的数据是时候，要统计某年的数据。开始时间是某年的第一天，结束时间是某年的最后一天。该如何获取某年的第一天和最后一天：

    private static String datePattern = "yyyy-MM-dd";

    
    public static String format(Date date, String pattern) {
        if (date == null)
            return "";
        return DateFormatUtils.format(date, pattern);
    }

    
    public static String formatDateTime(Date date) {
        if (date == null)
            return "";
        return DateFormatUtils.format(date, datePattern);
    }


    
    public static Date parseDateTime(String str) {
        if (str == null)
            return null;
        try {
            return DateUtils.parseDate(str, datePattern);
        } catch (ParseException e) {
            e.printStackTrace();
        }
        return null;
    }

    
    public static Date parseDateTime(String str, String dateTimePattern) {
        if (str == null)
            return null;
        try {
            return DateUtils.parseDate(str, Locale.CHINESE, dateTimePattern);
        } catch (ParseException e) {
            e.printStackTrace();
        }
        return null;
    }


    
    public static Date getCurrentFirstOfYear(){
        Calendar currCal=Calendar.getInstance();
        int currentYear = currCal.get(Calendar.YEAR);
        return getFirstOfYear(currentYear);
    }

    
    public static Date getCurrentLastOfYear(){
        Calendar currCal=Calendar.getInstance();
        int currentYear = currCal.get(Calendar.YEAR);
        return getLastOfYear(currentYear);
    }

    
    public static Date getFirstOfYear(int year){
        Calendar calendar = Calendar.getInstance();
        calendar.clear();
        calendar.set(Calendar.YEAR, year);
        return calendar.getTime();
    }



    
    public static Date getLastOfYear(int year){
        Calendar calendar = Calendar.getInstance();
        calendar.clear();
        calendar.set(Calendar.YEAR, year);
        calendar.roll(Calendar.DAY_OF_YEAR, -1);
        return calendar.getTime();
    }


    public static void main(String args[]) {
        System.out.println("=========current year=========");
        Date currentYearStart = getCurrentFirstOfYear();
        System.out.println(formatDateTime(currentYearStart));

        Date currentYearEnd = getCurrentLastOfYear();
        System.out.println(formatDateTime(currentYearEnd));
    }

结果：

=========current year=========
2022-01-01
2022-12-31

知道了当前年怎么获取，getLastOfYear(int year)

某年，求获取某年的年份就可以了，带入查询

    public static Date getFirstOfYear(Date date){
//        int year = date.getYear(); // date.getYear 该方法被废弃了
        int year = Integer.parseInt(String.format("%tY",date));
        return getFirstOfYear(year);
    }

   

    
    public static Date getLastOfYear(Date date){
        int year = Integer.parseInt(String.format("%tY",date));
        return getLastOfYear(year);
    }

    public static void main(String args[]) {

        System.out.println("=========before year=========");
        Date before = parseDateTime("2012-10-10 12:00:00");

        Date beforeYearStart = getFirstOfYear(before);
        System.out.println(formatDateTime(beforeYearStart));

        Date beforeEnd = getLastOfYear(before);
        System.out.println(formatDateTime(beforeEnd));
    }

结果：

=========before year=========
2012-01-01
2012-12-31

        获取某年的年份的第一天和最后一天，先获取某年的年份，这个应该有很多种方式，再获取当年的第一天和最后一天