Java时间与日期处理

浅浅的花香味﹌ 2023-09-24 16:15 80阅读 0赞

### 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);
    }