我有一个java.util.Date格式yyyy-mm-dd。我希望它是格式mm-dd-yyyy
以下是我为此转换尝试的示例实用程序：
// Setting the pattern
SimpleDateFormat sm = new SimpleDateFormat("mm-dd-yyyy");
// myDate is the java.util.Date in yyyy-mm-dd format
// Converting it into String using formatter
String strDate = sm.format(myDate);
//Converting the String back to java.util.Date
Date dt = sm.parse(strDate);
我得到的输出仍然不是格式mm-dd-yyyy。
请让我知道如何格式化java.util.Date从yyyy-mm-dd到mm-dd-yyyy
Date是自 Unix 纪元（1970 年 1 月 1 日 00:00:00 UTC）以来毫秒数的容器。
它没有格式的概念。
LocalDateTime ldt = LocalDateTime.now();
System.out.println(DateTimeFormatter.ofPattern("MM-dd-yyyy", Locale.ENGLISH).format(ldt));
System.out.println(DateTimeFormatter.ofPattern("yyyy-MM-dd", Locale.ENGLISH).format(ldt));
System.out.println(ldt);
输出...
05-11-2018
2018-05-11
2018-05-11T17:24:42.980
您应该使用ThreeTen Backport
例如...
Date myDate = new Date();
System.out.println(myDate);
System.out.println(new SimpleDateFormat("MM-dd-yyyy").format(myDate));
System.out.println(new SimpleDateFormat("yyyy-MM-dd").format(myDate));
System.out.println(myDate);
输出...
Wed Aug 28 16:20:39 EST 2013
08-28-2013
2013-08-28
Wed Aug 28 16:20:39 EST 2013
任何格式都没有改变基础Date值。这是DateFormatters的目的
更新了其他示例
以防万一第一个例子没有意义......
此示例使用两个格式化程序来格式化相同的日期。然后我使用这些相同的格式化程序将值解析String回Dates。生成的解析不会改变Date报告其值的方式。
Date#toString只是其内容的转储。您无法更改此设置，但您可以以Date任何您喜欢的方式格式化对象
try {
Date myDate = new Date();
System.out.println(myDate);
SimpleDateFormat mdyFormat = new SimpleDateFormat("MM-dd-yyyy");
SimpleDateFormat dmyFormat = new SimpleDateFormat("yyyy-MM-dd");
// Format the date to Strings
String mdy = mdyFormat.format(myDate);
String dmy = dmyFormat.format(myDate);
// Results...
System.out.println(mdy);
System.out.println(dmy);
// Parse the Strings back to dates
// Note, the formats don't "stick" with the Date value
System.out.println(mdyFormat.parse(mdy));
System.out.println(dmyFormat.parse(dmy));
} catch (ParseException exp) {
exp.printStackTrace();
}
哪个输出...
Wed Aug 28 16:24:54 EST 2013
08-28-2013
2013-08-28
Wed Aug 28 00:00:00 EST 2013
Wed Aug 28 00:00:00 EST 2013
另外，请注意格式模式。仔细查看SimpleDateFormat以确保您没有使用错误的模式；）
SimpleDateFormat("MM-dd-yyyy");
代替
SimpleDateFormat("mm-dd-yyyy");
因为MM points Month，mm points minutes
SimpleDateFormat sm = new SimpleDateFormat("MM-dd-yyyy");
String strDate = sm.format(myDate);
“M”（大写）代表月份，“m”（简单）代表分钟
几个月的一些例子
'M' -> 7 (without prefix 0 if it is single digit)
'M' -> 12
'MM' -> 07 (with prefix 0 if it is single digit)
'MM' -> 12
'MMM' -> Jul (display with 3 character)
'MMMM' -> December (display with full name)
几分钟的例子
'm' -> 3 (without prefix 0 if it is single digit)
'm' -> 19
'mm' -> 03 (with prefix 0 if it is single digit)
'mm' -> 19
请将小“mm”月份更改为大写“MM”，它将起作用。以下是示例代码供参考。
Date myDate = new Date();
SimpleDateFormat sm = new SimpleDateFormat("MM-dd-yyyy");
String strDate = sm.format(myDate);
Date dt = sm.parse(strDate);
System.out.println(strDate);
您可能会得到日、月和年，并且可以将它们连接起来，或者可以使用 MM-dd-yyyy 格式，如下所示。
Date date1 = new Date();
String mmddyyyy1 = new SimpleDateFormat("MM-dd-yyyy").format(date1);
System.out.println("Formatted Date 1: " + mmddyyyy1);
Date date2 = new Date();
Calendar calendar1 = new GregorianCalendar();
calendar1.setTime(date2);
int day1 = calendar1.get(Calendar.DAY_OF_MONTH);
int month1 = calendar1.get(Calendar.MONTH) + 1; // {0 - 11}
int year1 = calendar1.get(Calendar.YEAR);
String mmddyyyy2 = ((month1<10)?"0"+month1:month1) + "-" + ((day1<10)?"0"+day1:day1) + "-" + (year1);
System.out.println("Formatted Date 2: " + mmddyyyy2);
LocalDateTime ldt1 = LocalDateTime.now();
DateTimeFormatter format1 = DateTimeFormatter.ofPattern("MM-dd-yyyy");
String mmddyyyy3 = ldt1.format(format1);
System.out.println("Formatted Date 3: " + mmddyyyy3);
LocalDateTime ldt2 = LocalDateTime.now();
int day2 = ldt2.getDayOfMonth();
int mont2= ldt2.getMonthValue();
int year2= ldt2.getYear();
String mmddyyyy4 = ((mont2<10)?"0"+mont2:mont2) + "-" + ((day2<10)?"0"+day2:day2) + "-" + (year2);
System.out.println("Formatted Date 4: " + mmddyyyy4);
LocalDateTime ldt3 = LocalDateTime.of(2020, 6, 11, 14, 30); // int year, int month, int dayOfMonth, int hour, int minute
DateTimeFormatter format2 = DateTimeFormatter.ofPattern("MM-dd-yyyy");
String mmddyyyy5 = ldt3.format(format2);
System.out.println("Formatted Date 5: " + mmddyyyy5);
Calendar calendar2 = Calendar.getInstance();
calendar2.setTime(new Date());
int day3 = calendar2.get(Calendar.DAY_OF_MONTH); // OR Calendar.DATE
int month3= calendar2.get(Calendar.MONTH) + 1;
int year3 = calendar2.get(Calendar.YEAR);
String mmddyyyy6 = ((month3<10)?"0"+month3:month3) + "-" + ((day3<10)?"0"+day3:day3) + "-" + (year3);
System.out.println("Formatted Date 6: " + mmddyyyy6);
Date date3 = new Date();
LocalDate ld1 = LocalDate.parse(new SimpleDateFormat("yyyy-MM-dd").format(date3)); // Accepts only yyyy-MM-dd
int day4 = ld1.getDayOfMonth();
int month4= ld1.getMonthValue();
int year4 = ld1.getYear();
String mmddyyyy7 = ((month4<10)?"0"+month4:month4) + "-" + ((day4<10)?"0"+day4:day4) + "-" + (year4);
System.out.println("Formatted Date 7: " + mmddyyyy7);
Date date4 = new Date();
int day5 = LocalDate.parse(new SimpleDateFormat("yyyy-MM-dd").format(date4)).getDayOfMonth();
int month5 = LocalDate.parse(new SimpleDateFormat("yyyy-MM-dd").format(date4)).getMonthValue();
int year5 = LocalDate.parse(new SimpleDateFormat("yyyy-MM-dd").format(date4)).getYear();
String mmddyyyy8 = ((month5<10)?"0"+month5:month5) + "-" + ((day5<10)?"0"+day5:day5) + "-" + (year5);
System.out.println("Formatted Date 8: " + mmddyyyy8);
Date date5 = new Date();
int day6 = Integer.parseInt(new SimpleDateFormat("dd").format(date5));
int month6 = Integer.parseInt(new SimpleDateFormat("MM").format(date5));
int year6 = Integer.parseInt(new SimpleDateFormat("yyyy").format(date5));
String mmddyyyy9 = ((month6<10)?"0"+month6:month6) + "-" + ((day6<10)?"0"+day6:day6) + "-" + (year6);`enter code here`
System.out.println("Formatted Date 9: " + mmddyyyy9);
下面的代码很简单。
final Date todayDate = new Date();
System.out.println(todayDate);
System.out.println(new SimpleDateFormat("MM-dd-yyyy").format(todayDate));
System.out.println(new SimpleDateFormat("yyyy-MM-dd").format(todayDate));
System.out.println(todayDate);