Java 日/月/年与日/月/年？
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dd/mm/yyyy vs dd/MM/yyyy?
提问by user3198603
SimpleDateFormat sdf = new SimpleDateFormat("dd/MM/yyyy");
String date = sdf.format(new Date());
System.out.println(date);
Result is todays date i.e 23/03/2014
结果是今天的日期，即 23/03/2014
But when i do
但是当我这样做时
SimpleDateFormat sdf = new SimpleDateFormat("dd/mm/yyyy");
result can be 23/05/2014, 23/05/2014, 23/06/2014 and son with each run of prgram. Why so?
结果可以是 23/05/2014、23/05/2014、23/06/2014 和儿子，每次运行程序。为什么这样？
采纳答案by T.J. Crowder
As we can see from the documentation, it's because mmis for minutes, not months.
回答by Salah
mmrepresents minutes, so when you use mm, it will print minutes instead of month.
mm代表分钟，所以当你使用时mm，它会打印分钟而不是月份。
While MMrepresents months.
whileMM代表月份。
Read more about Time Patterns
阅读更多关于 Time Patterns
回答by Shell
In C# and VB.NET, it's a case sensitive especially to format the Month or Minutes. Because initial character of both the words is same.
在 C# 和 VB.NET 中，它是区分大小写的，尤其是格式化月份或分钟。因为这两个词的首字母相同。
The following detail may help you in formatting the date & time.
以下详细信息可以帮助您格式化日期和时间。
1. d/D: day without 0 prefix on single digit.
2. dd/DD: day with 0 prefix if single digit.
3. M: Month without 0 prefix on single digit.
4. MM: Month with 0 prefix if single digit.
5. yy/YY: Last two digit of year.
6. yyyy/YYYY: represents full year.
7. HH: 24 hour based hour. ie. 13:00. **H** will display hour without prefix 0 if single digit
8. hh: 12 hour based hour. ie. 01:00. **h** will display hour without prefix 0 if single digit
9. m: minute without 0 prefix on single digit.
10.mm: minute with 0 prefix if single digit.
11.s: second without 0 prefix on single digit.
12.ss: second with 0 prefix if single digit.
13.tt: represent the AM or PM
回答by sanjeevjha
Yes it is because mmrepresents minutes
是的，因为mm代表minutes
Date date=new Date();
System.out.println(date);
System.out.println("Date: "+new SimpleDateFormat("dd/MM/yyyy").format(date));
System.out.println("Date: "+new SimpleDateFormat("dd/mm/yyyy").format(date));
if you observed the output you will find when we print date object, there is value of minutes, month, etc and in 2nd line and 3rd line same minute is printed corresponding to mm and month value is printed corresponding to MM
如果您观察输出，您会发现当我们打印日期对象时，有分钟，月份等值，并且在第 2 行和第 3 行中，相同的分钟对应于 mm 打印，月份值对应于 MM 打印
Thu Feb 20 14:33:00 IST 2020
20/02/2020
20/33/2020
