java天数计算函数(当前月天数、某月总天数、某月剩余天数)4种方法实现

缺乏、安全感 2023-10-09 23:39 118阅读 0赞

**1,Java8 LocalDate**

public static int getDaysOfMonth(String dateStr) {
            LocalDate date = LocalDate.parse(dateStr + "-01");
            return date.lengthOfMonth();
        }

**2,利用日历函数**

public static int getDaysOfMonth(String dateStr) throws ParseException {
            SimpleDateFormat sdf = new SimpleDateFormat("yyyy-MM");
            Calendar calendar = Calendar.getInstance();
            calendar.setTime(sdf.parse(dateStr));
            return calendar.getActualMaximum(Calendar.DAY_OF_MONTH);
        }

**3,也是利用日历函数，但是不需要 throws ParseException**

/**
         * 获取日期当月的天数
         * @param dateStr yyyy-MM 或者yyyy-MM-dd
         * */
        public static int getDaysByDate(String dateStr){
            int year= Integer.parseInt(dateStr.substring(0,4));
            int month=Integer.parseInt(dateStr.substring(5,7));
            Calendar c = Calendar.getInstance();
            c.set(year, month, 0);
            return c.get(Calendar.DAY_OF_MONTH);
        }

**测试样例代码：**

String dateStr = "2023-01";
            int days = getDaysOfMonth(dateStr);
            System.out.println(dateStr + " has " + days + " days.");

**4,当月剩余天数**

/**
         * 当月剩余天数
         * @param date 格式yyyy-MM-dd
         * */
        public static Integer monthEndNum(String date){
            SimpleDateFormat format=new SimpleDateFormat("yyyy-MM-dd");
            Date dateTime = null;
            try {
                dateTime = format.parse(date);
            } catch (ParseException e) {
                e.printStackTrace();
            }
            Calendar c = Calendar.getInstance();
            c.setTime(dateTime);
            int today = c.get(Calendar.DAY_OF_MONTH);
            int last = c.getActualMaximum(Calendar.DAY_OF_MONTH);
            return last - today;
        }
     
      public static void main(String[] args) {
            Integer days = monthEndNum("2023-01-20");
            System.out.println("2023年1月剩余天数:"+days);
        }

**5，获取当前月天数**

//获取当前月的天数
        public static int getDaysOfCurrentMonth() {
            Calendar calendar = Calendar.getInstance();
            return calendar.getActualMaximum(Calendar.DAY_OF_MONTH);
        }

测试代码：

public static void main(String[] args) throws ParseException {
            Date currentTime = new Date();
            SimpleDateFormat formatter = new SimpleDateFormat("yyyy-MM-dd HH:mm:ss");
            String dateString = formatter.format(currentTime);
            System.out.println(dateString);
    
            SimpleDateFormat dateFormat = new SimpleDateFormat("yyyy年MM月dd日HH时mm分ss秒");
            String dateString2 = dateFormat.format(currentTime);
            System.out.println(dateString2);
    
            Date date1 = dateFormat.parse(dateString2);
            String dateString3 = formatter.format(date1);
            System.out.println(dateString3);
    
    
            // 将日期字符串转换为LocalDate对象
            LocalDate date = LocalDate.parse("2023-04-06");
            // 将LocalDate对象格式化为指定格式的字符串
            DateTimeFormatter formatter1 = DateTimeFormatter.ofPattern("yyyy年M月d日");
            String formattedDate = date.format(formatter1);
            System.out.println(formattedDate);
            // 将格式化后的字符串转换为LocalDate对象
            LocalDate parsedDate = LocalDate.parse(formattedDate, formatter1);
            // 将LocalDate对象转换为指定格式的字符串
            String parsedDateString = parsedDate.format(DateTimeFormatter.ofPattern("yyyy-MM-dd"));
            System.out.println(parsedDateString);
            // 确认两个日期字符串相等
            assert parsedDateString.equals("2023-04-06");
            // 确认两个LocalDate对象相等
            assert parsedDate.equals(date);
    
            System.out.println("---------------------");
            String sdate="2023-04-06";
            String sdate2="2023年4月6日";
            String sdate3="2023-04";
            String sdate4="2023年4月";
            System.out.println(convertDateToChs(sdate));
            System.out.println(convertToChinese(sdate));
            System.out.println((convertDateToEn(sdate2)));
            System.out.println((convertDateToEnglish(sdate2)));
            System.out.println((convertToShortChinese(sdate3)));
            System.out.println((convertToShortEnglish(sdate4)));
    
    
            String dateStr = "2023-02";
            int days = getDaysByDate(dateStr);
            System.out.println(dateStr + " has " + days + " days.");
    
            System.out.println("今年有" +   getDaysInCurrentYear() + " days.");
            System.out.println("今年已过去" +   getDaysPassedInCurrentYear() + " days.");
            System.out.println("今年剩余" +   getDaysEndInCurrentYear() + " days.");
    
        }

测试效果截图：

![27fa742545624d43ac6f622edbd6862f.png][]

[27fa742545624d43ac6f622edbd6862f.png]: https://img-blog.csdnimg.cn/27fa742545624d43ac6f622edbd6862f.png