开发的时候用到这个类进行日期的转换,想转换的日期格式为“YYYY/MM/dd”,结果在2018年12月30日那天转换出来的格式是2019/12/30,请看下面的代码:

public static void main(String[] args) {

DateTimeFormatter dtf = DateTimeFormatter.ofPattern("YYYY/MM/dd");

DateTimeFormatter dtf2 = DateTimeFormatter.ofPattern("yyyy/MM/dd");

LocalDate localDate = LocalDate.of(2018, 12, 30);

System.out.println("日期1:"+dtf.format(localDate));

System.out.println("日期2:"+dtf2.format(localDate));

}

以上代码出来的结果为:

 关于日期格式yyyy-MM-dd和YYYY-MM-dd_扫一扫

 

所以同学们在用日期转换类的时候要注意了,下面列一下不同的字符表示的含义:

Pattern

 

 



All letters 'A' to 'Z' and 'a' to 'z' are reserved as pattern letters. The following pattern letters are defined: 

Symbol Meaning Presentation Examples
------ ------- ------------ -------
G era text AD; Anno Domini; A
u year year 2004; 04
y year-of-era year 2004; 04
D day-of-year number 189
M/L month-of-year number/text 7; 07; Jul; July; J
d day-of-month number 10

Q/q quarter-of-year number/text 3; 03; Q3; 3rd quarter
Y week-based-year year 1996; 96
w week-of-week-based-year number 27
W week-of-month number 4
E day-of-week text Tue; Tuesday; T
e/c localized day-of-week number/text 2; 02; Tue; Tuesday; T
F week-of-month number 3

a am-pm-of-day text PM
h clock-hour-of-am-pm (1-12) number 12
K hour-of-am-pm (0-11) number 0
k clock-hour-of-am-pm (1-24) number 0

H hour-of-day (0-23) number 0
m minute-of-hour number 30
s second-of-minute number 55
S fraction-of-second fraction 978
A milli-of-day number 1234
n nano-of-second number 987654321
N nano-of-day number 1234000000

V time-zone ID zone-id America/Los_Angeles; Z; -08:30
z time-zone name zone-name Pacific Standard Time; PST
O localized zone-offset offset-O GMT+8; GMT+08:00; UTC-08:00;
X zone-offset 'Z' for zero offset-X Z; -08; -0830; -08:30; -083015; -08:30:15;
x zone-offset offset-x +0000; -08; -0830; -08:30; -083015; -08:30:15;
Z zone-offset offset-Z +0000; -0800; -08:00;

p pad next pad modifier 1

' escape for text delimiter
'' single quote literal '
[ optional section start
] optional section end
# reserved for future use
{ reserved for future use
} reserved for future use


 

 当天所在的周属于的年份,一周从周日开始,周六结束,只要本周跨年,那么这周就算入下一年。这个结论在正向转换的时候是没有问题的,但是在逆向转换的时候是有问题的。