Java中的SimpleDateFormat工作不正确还是我做错了？查看代码示例 [英] Is SimpleDateFormat in Java work incorrect or I did any mistake? See code sample

问题描述

我使用Java并使用sdk 7编译此代码。
控制台显示：

I use Java and compile this code using sdk 7. Console show:

input = 2010/03/30

input=2010/03/30

output = 2010/12/28

output=2010/12/28

public static void main(String[] args) {
    SimpleDateFormat format = new SimpleDateFormat("YYYY/MM/dd");
    String inputDateStr = "2010/03/30";
    try {
        Date date = format.parse(inputDateStr);
        String result = format.format(date);
        System.out.println("input=" + inputDateStr);
        System.out.println("output=" + result);
    } catch (ParseException e) {
        e.printStackTrace();
    }
}

推荐答案

As用于文档 https://docs.oracle.com/ javase / 7 / docs / api / java / text / SimpleDateFormat.html
大写字母 D 表示年，如果要在月中使用天数，则应使用小写的 d 。

As for documentation https://docs.oracle.com/javase/7/docs/api/java/text/SimpleDateFormat.html uppercase D stands for the day number in a year, if you want day number in a month you should use lowercase d.

YYYY 和 yyyy 相同：

Letter  Date or Time Component  Presentation    Examples
G   Era designator  Text    AD
y   Year    Year    1996; 96
Y   Week year   Year    2009; 09
M   Month in year   Month   July; Jul; 07
w   Week in year    Number  27
W   Week in month   Number  2
D   Day in year Number  189
d   Day in month    Number  10
F   Day of week in month    Number  2
E   Day name in week    Text    Tuesday; Tue
u   Day number of week (1 = Monday, ..., 7 = Sunday)    Number  1
a   Am/pm marker    Text    PM
H   Hour in day (0-23)  Number  0
k   Hour in day (1-24)  Number  24
K   Hour in am/pm (0-11)    Number  0
h   Hour in am/pm (1-12)    Number  12
m   Minute in hour  Number  30
s   Second in minute    Number  55
S   Millisecond Number  978
z   Time zone   General time zone   Pacific Standard Time; PST; GMT-08:00
Z   Time zone   RFC 822 time zone   -0800
X   Time zone   ISO 8601 time zone  -08; -0800; -08:00

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