Java时间与日期处理-蒲公英云

Java时间与日期处理

返回指定格式的当前时间

Date date = new Date();
 SimpleDateFormat simpleDateFormat = new SimpleDateFormat("yyyy-MM-dd");
 String datestring  = simpleDateFormat.format(date);
 System.out.printf(datestring);

返回固定格式的Date类型时间Date—》ToString—》ToDate

public  static String TimeFormat ="yyyy-MM-dd";
    public static void main(String[] args) {
        Date date =new Date(System.currentTimeMillis());
        SimpleDateFormat simpleDateFormat = new SimpleDateFormat(TimeFormat);
        String dateformat=simpleDateFormat.format(date);
        System.out.printf(dateformat);
        Date dateafterFormat =null;
        try {
            dateafterFormat=simpleDateFormat.parse(dateformat);
            System.out.printf(String.valueOf(dateafterFormat));
        } catch (ParseException e) {
            throw new RuntimeException(e);
        }
    }

字符串转日期

#parse(String text, ParsePosition pos)
#解析字符串中的文本以Date生成,parase需要背用try-catch包围
 String dateTime ="2023-01-16 17:35:16";
  SimpleDateFormat simpleDateFormat = new SimpleDateFormat("yyyy-MM-dd");
    try {
        Date date =simpleDateFormat.parse(dateTime);
        System.out.printf(date.toString());
    } catch (ParseException e) {
        throw new RuntimeException(e);
}

两时间关系判断构件

#时间相等返回0，time1大于time2返回1，time1小于time2返回-1
  Date time1 = new Date(System.currentTimeMillis());
  String date ="2023-01-17 17:35:16";
   Date time2 = null;
   try {
       time2 = new SimpleDateFormat("yyyy-MM-dd").parse(date);
   } catch (ParseException e) {
       throw new RuntimeException(e);
   }
   int flag =time1.compareTo(time2);
   System.out.printf(flag+"");

Date转换为字符串

public static String date2Str(Date date, String format) {
        if (null == date) {
            return null;
        }
        SimpleDateFormat sdf = new SimpleDateFormat(format);
        return sdf.format(date);
}