SimpleDateFormat无法解析超过4位数的毫秒数

问题描述

我想解析时间戳，如下所示 - 2016-03-16 01：14：21.6739。但是当我使用 SimpleDateFormat 来解析它时，我发现它输出了一个不正确的解析值。它将隐藏6739毫秒到6秒，剩下739毫秒。它将日期转换为此格式 - Wed Mar 16 01:14:27 PDT 2016 。为什么秒部分从21秒变为27秒（增加6秒？）。以下是我的代码片段：

I want to parse a timestamp, like this - "2016-03-16 01:14:21.6739". But when I use the SimpleDateFormat to parse it, I find that it outputs an incorrect parsed value. It will covert 6739 milliseconds to 6 seconds with 739 millseconds left. It converted the date to this format - Wed Mar 16 01:14:27 PDT 2016. Why the seconds part has changed from 21 seconds to 27 seconds(an addition of 6 seconds?). The following is my code snippet:

final SimpleDateFormat sf = new SimpleDateFormat("yyyy-MM-dd HH:mm:ss.SSSS");
String parsedate="2016-03-16 01:14:21.6739";
try {
    Date outputdate = sf.parse(parsedate);
    String newdate = outputdate.toString();  //==output date is: Wed Mar 16 01:14:27 PDT 2016 
    System.out.println(newdate);
} catch (ParseException e) {
    // TODO Auto-generated catch block
    e.printStackTrace();
}

推荐答案

似乎不可能使用SimpleDateFormat以比毫秒更精细的粒度表达时间。
发生的事情是，当你输入6739时，Java将其理解为6739毫秒，即6秒和739毫秒，因此观察到6秒的差异。

It seems that is not possible to use SimpleDateFormat to express times with a finer grain than the millisecond.What is happening is that as you put 6739, Java understands it as 6739 milliseconds i.e. 6 seconds and 739 milliseconds hence the 6 seconds difference observed.

检查这些其中，它解释得很好：

Check these ones, it is explained quite well: String-Date conversion with nanoseconds Java date parsing with microsecond or nanosecond accuracy

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