从 Java 日历中解析日期
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Parsing date from Calendar in Java
提问by Vishal
I am having following function
我有以下功能
public static Date parseDate(String date, String format) throws ParseException
{
SimpleDateFormat formatter = new SimpleDateFormat(format);
return formatter.parse(date);
}
I am using this as follows in my code
我在我的代码中使用如下
Calendar eDate = Calendar.getInstance();
eDate.add(Calendar.DAY_OF_MONTH,10);
Date date = null;
try {
date = parseDate(eDate.getTime().toString(),"yyyy-MM-dd hh-mm-ss");
} catch (ParseException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
But it is throwing -
但它正在抛出 -
java.text.ParseException: Unparseable date
What is the problem here?
这里有什么问题？
采纳答案by BalusC
The format is not stored in the Date. It is stored in the String. The Date#toString()returns a fixedformat which is described in its Javadoc.
格式不存储在Date. 它存储在String. 所述Date#toString()返回一个固定其以其格式描述的Javadoc。
Do the formatting only at the momentyou need to display a Dateto a human as a String.
仅在您需要Date将 a 作为String.
Calendar calendar = Calendar.getInstance();
calendar.add(Calendar.DAY_OF_MONTH, 10);
Date date = calendar.getTime();
String formattedDate = new SimpleDateFormat("yyyy-MM-dd HH:mm:ss").format(date);
System.out.println(formattedDate);
Note that MMstands for months and mmfor minutes. See also SimpleDateFormatjavadoc.
请注意，MM代表月份和mm分钟。另请参阅SimpleDateFormatjavadoc。
回答by Jon Skeet
You're currently formattingwith the default format from java.util.Date, and then parsingwith a potentially different format. You should also change your format string - it's currently using a 12 hour clock with no am/pm indicator, and minutes twice. I think you mean: "yyyy-MM-dd HH-mm-ss"
您目前的格式与默认格式java.util.Date，然后解析与潜在不同的格式。您还应该更改您的格式字符串 - 它当前使用的是 12 小时制，没有 am/pm 指示器，并且两次使用分钟。我想你的意思是：“yyyy-MM-dd HH-mm-ss”
回答by Christopher Klewes
You're inserting a Zulu Timestamp (UNIX), getTime()returns the number of milliseconds since January 1, 1970, 00:00:00 GMT. Then you define the format as yyyy-mm-dd hh-mm-ssand try to parse the timestamp with this pattern. Which doesn't match.
您正在插入 Zulu Timestamp (UNIX)，getTime()返回自January 1, 1970, 00:00:00 GMT. 然后将格式定义为yyyy-mm-dd hh-mm-ss并尝试使用此模式解析时间戳。哪个不匹配。
You could use Date date = calendar.getTime();and then format it via new SimpleDateFormat("yyyy-MM-dd HH-mm-ss").format(date);
您可以使用Date date = calendar.getTime();然后通过new SimpleDateFormat("yyyy-MM-dd HH-mm-ss").format(date);
回答by Carl Smotricz
You'll be happy to hear that there's never a need to parse a date from a Calendarobject: The way to pull a Dateout of a Calendaris via the getTime()method.
你会很高兴地听到，有从来不需要解析从约会Calendar对象：拉的方式Date进行的Calendar是通过getTime()方法。
EDIT:
编辑：
To output the date in eDatein ISO style format:
以eDateISO 样式格式输出日期：
final DateFormat isoFormat = new SimpleDateFormat("yyyy-MM-dd HH-mm-ss");
String formattedDate = isoFormat.format(eDate.getTime());
That's untested, but I think it should work.
这是未经测试的，但我认为它应该有效。
回答by Bozho
Don't use toString()for anything like that. toString()should be used only for debug messages.
不要toString()用于类似的事情。toString()应该仅用于调试消息。
Use DateFormat.format(..)to produce a string in a predictable form.
用于DateFormat.format(..)以可预测的形式生成字符串。
回答by Eyal Schneider
you can simply use the date returned by the calendar, instead of transforming it into string and back into a date (apparently using a wrong date format). The date can be obtained by:
您可以简单地使用日历返回的日期，而不是将其转换为字符串并重新转换为日期（显然使用错误的日期格式）。日期可以通过以下方式获得：
eDate.getTime()
There seems to be no need for SimpleDateFormat in your case.
在您的情况下似乎不需要 SimpleDateFormat 。
回答by Chris Cudmore
Check the Date.toString() method.
检查 Date.toString() 方法。
The api states that it returns it in the format:
api 声明它以以下格式返回它：
dow mon dd hh:mm:ss zzz yyyy
which is:
即：
Mon Jan 28 14:22:07 EST 2004
You are telling the parser to expect: 2004-01-28 14-22-07
您告诉解析器期望： 2004-01-28 14-22-07
回答by CodeClimber
eDate.getTime().toString()
returns a String representation of a date in this format:
以这种格式返回日期的字符串表示形式：
dow mon dd hh:mm:ss zzz yyyy (see the java.util.Date API).
dow mon dd hh:mm:ss zzz yyyy（请参阅 java.util.Date API）。
You are trying to parse a date using this format:
您正在尝试使用以下格式解析日期：
yyyy-mm-dd hh-mm-ss .
yyyy-mm-dd hh-mm-ss 。
The code is correctly throwing the ParseException.
代码正确抛出 ParseException。
