String str_date = "11-June-07";
DateFormat formatter = new SimpleDateFormat("dd-MMM-yy");
Date date = formatter.parse(str_date);

DateFormat dateFormat = new SimpleDateFormat("yyyy-MM-dd");
Date date;
try {
    date = dateFormat.parse("2013-12-4");
    System.out.println(date.toString()); // Wed Dec 04 00:00:00 CST 2013

    String output = dateFormat.format(date);
    System.out.println(output); // 2013-12-04
} 
catch (ParseException e) {
    e.printStackTrace();
}

这对我来说很有效。

在Java 8中，我们获得了一个新的日期/时间API (JSR 310)。

下面的方法可以用来解析Java 8中的日期而不依赖于Joda-Time:

 String str = "January 2nd, 2010";

// if we 2nd even we have changed in pattern also it is not working please workout with 2nd 
DateTimeFormatter formatter = DateTimeFormatter.ofPattern("MMMM Q, yyyy", Locale.ENGLISH);
LocalDate date = LocalDate.parse(str, formatter);

// access date fields
int year = date.getYear(); // 2010
int day = date.getDayOfMonth(); // 2
Month month = date.getMonth(); // JANUARY
int monthAsInt = month.getValue(); // 1

LocalDate是表示日期(没有时间)的标准Java 8类。如果要解析包含日期和时间信息的值，则应该使用LocalDateTime。对于带时区的值，请使用ZonedDateTime。两者都提供了类似于LocalDate的parse()方法:

LocalDateTime dateWithTime = LocalDateTime.parse(strWithDateAndTime, dateTimeFormatter);
ZonedDateTime zoned = ZonedDateTime.parse(strWithTimeZone, zoneFormatter);

DateTimeFormatter Javadoc中的格式化字符列表:

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;

虽然有些答案在技术上是正确的，但它们并不可取。

The java.util.Date & Calendar classes are notoriously troublesome. Because of flaws in design and implementation, avoid them. Fortunately we have our choice of two other excellent date-time libraries: Joda-TimeThis popular open-source free-of-cost library can be used across several versions of Java. Many examples of its usage may be found on StackOverflow. Reading some of these will help get you up to speed quickly. java.time.* packageThis new set of classes are inspired by Joda-Time and defined by JSR 310. These classes are built into Java 8. A project is underway to backport these classes to Java 7, but that backporting is not backed by Oracle. As Kristopher Johnson correctly noted in his comment on the question, the other answers ignore vital issues of: Time of DayDate has both a date portion and a time-of-day portion) Time ZoneThe beginning of a day depends on the time zone. If you fail to specify a time zone, the JVM's default time zone is applied. That means the behavior of your code may change when run on other computers or with a modified time zone setting. Probably not what you want. LocaleThe Locale's language specifies how to interpret the words (name of month and of day) encountered during parsing. (The answer by BalusC handles this properly.) Also, the Locale affects the output of some formatters when generating a string representation of your date-time.

乔达时间

下面是关于Joda-Time的一些注意事项。

时区

在Joda-Time中，DateTime对象真正知道自己分配的时区。这与java.util.Date类形成对比，后者似乎有时区，但实际上没有。

请注意，在下面的示例代码中，我们如何将一个时区对象传递给解析字符串的格式化程序。该时区用于将日期-时间解释为发生在该时区。因此，您需要考虑并确定由字符串输入表示的时区。

由于您的输入字符串中没有时间部分，所以Joda-Time将指定时区的第一个时刻分配为一天的时间。通常这意味着00:00:00，但并不总是如此，因为日光节约时间(DST)或其他异常情况。顺便说一下，你可以通过调用withTimeAtStartOfDay对任何DateTime实例做同样的事情。

格式化程序模式

格式化程序模式中使用的字符在Joda-Time中类似于java.util中的字符。日期/日历，但不完全相同。仔细阅读诊断书。

不变性

我们通常在Joda-Time中使用不可变类。我们不会修改现有的Date-Time对象，而是调用基于其他对象创建新实例的方法，复制大多数方面(除非需要更改的地方除外)。下面最后一行中的withZone调用就是一个例子。不可变性有助于使Joda-Time非常线程安全，也可以使一些工作更加清晰。

转换

你将需要java.util.Date对象与其他不知道Joda-Time对象的类/框架一起使用。幸运的是，来回移动非常容易。

从java.util.Date对象(这里命名为date)到Joda-Time DateTime…

org.joda.time.DateTime dateTime = new DateTime( date, timeZone );

从Joda-Time到java.util.Date对象……

java.util.Date date = dateTime.toDate();

示例代码

String input = "January 2, 2010";

java.util.Locale locale = java.util.Locale.US;
DateTimeZone timeZone = DateTimeZone.forID( "Pacific/Honolulu" ); // Arbitrarily chosen for example.
DateTimeFormatter formatter = DateTimeFormat.forPattern( "MMMM d, yyyy" ).withZone( timeZone ).withLocale( locale );
DateTime dateTime = formatter.parseDateTime( input );

System.out.println( "dateTime: " + dateTime );
System.out.println( "dateTime in UTC/GMT: " + dateTime.withZone( DateTimeZone.UTC ) );

运行时……

dateTime: 2010-01-02T00:00:00.000-10:00
dateTime in UTC/GMT: 2010-01-02T10:00:00.000Z

您可以使用SimpleDateformat更改日期字符串

sdf = new SimpleDateFormat("yyyy-MM-dd"); String strDate = "2000-01-01"; Date Date = sdf.parse(strDate);

啊，又是Java Date的讨论。为了处理日期操作，我们使用date、Calendar、GregorianCalendar和SimpleDateFormat。例如，用你一月份的日期作为输入:

Calendar mydate = new GregorianCalendar();
String mystring = "January 2, 2010";
Date thedate = new SimpleDateFormat("MMMM d, yyyy", Locale.ENGLISH).parse(mystring);
mydate.setTime(thedate);
//breakdown
System.out.println("mydate -> "+mydate);
System.out.println("year   -> "+mydate.get(Calendar.YEAR));
System.out.println("month  -> "+mydate.get(Calendar.MONTH));
System.out.println("dom    -> "+mydate.get(Calendar.DAY_OF_MONTH));
System.out.println("dow    -> "+mydate.get(Calendar.DAY_OF_WEEK));
System.out.println("hour   -> "+mydate.get(Calendar.HOUR));
System.out.println("minute -> "+mydate.get(Calendar.MINUTE));
System.out.println("second -> "+mydate.get(Calendar.SECOND));
System.out.println("milli  -> "+mydate.get(Calendar.MILLISECOND));
System.out.println("ampm   -> "+mydate.get(Calendar.AM_PM));
System.out.println("hod    -> "+mydate.get(Calendar.HOUR_OF_DAY));

然后你可以用类似这样的东西来操纵它:

Calendar now = Calendar.getInstance();
mydate.set(Calendar.YEAR,2009);
mydate.set(Calendar.MONTH,Calendar.FEBRUARY);
mydate.set(Calendar.DAY_OF_MONTH,25);
mydate.set(Calendar.HOUR_OF_DAY,now.get(Calendar.HOUR_OF_DAY));
mydate.set(Calendar.MINUTE,now.get(Calendar.MINUTE));
mydate.set(Calendar.SECOND,now.get(Calendar.SECOND));
// or with one statement
//mydate.set(2009, Calendar.FEBRUARY, 25, now.get(Calendar.HOUR_OF_DAY), now.get(Calendar.MINUTE), now.get(Calendar.SECOND));
System.out.println("mydate -> "+mydate);
System.out.println("year   -> "+mydate.get(Calendar.YEAR));
System.out.println("month  -> "+mydate.get(Calendar.MONTH));
System.out.println("dom    -> "+mydate.get(Calendar.DAY_OF_MONTH));
System.out.println("dow    -> "+mydate.get(Calendar.DAY_OF_WEEK));
System.out.println("hour   -> "+mydate.get(Calendar.HOUR));
System.out.println("minute -> "+mydate.get(Calendar.MINUTE));
System.out.println("second -> "+mydate.get(Calendar.SECOND));
System.out.println("milli  -> "+mydate.get(Calendar.MILLISECOND));
System.out.println("ampm   -> "+mydate.get(Calendar.AM_PM));
System.out.println("hod    -> "+mydate.get(Calendar.HOUR_OF_DAY));