blocks|key|189715|text|为了安全起见，我建议先将它们转换为日期，但只要您确定格式(或时区等)在你身上永远不会改变，那么日期比较和字符串格式的比较应该总是等价的。|type|unstyled|depth|inlineStyleRanges|entityRanges|data|189716|entityMap^0|0^^$0|@$1|2|3|4|5|6|7|D|8|@]|9|@]|A|$]]|$1|B|3|-4|5|6|7|E|8|@]|9|@]|A|$]]]|C|$]]

I would recommend converting them to date first to be a little safer, but as long as you are SURE the format (or timezone, etc...) will never change on you, then a date compare and comparing that format of string should always be equivalent.

blocks|key|407897|text|您的方法很好，因为yyyy-mm-dd+hh:ii:ss可以作为字符串进行比较，并获得正确的结果，其他日期格式将失败|type|unstyled|depth|inlineStyleRanges|entityRanges|data|407898|另一种选择是阅读此堆栈溢出问题|407899|How+to+compare+dates+in+Java?|offset|length|407900|你应该简单地解析你的字符串并创建Date或Calendar对象，这取决于你想做什么，下面是我觉得有用的东西|407901|http://www.mkyong.com/java/java-how-to-get-current-date-time-date-and-calender/|407902|entityMap|0|LINK|mutability|MUTABLE|url|https://stackoverflow.com/questions/2592501/compare-dates-in-java|1^0|0|0|0|T|0|0|0|0|27|1|0^^$0|@$1|2|3|4|5|6|7|U|8|@]|9|@]|A|$]]|$1|B|3|C|5|6|7|V|8|@]|9|@]|A|$]]|$1|D|3|E|5|6|7|W|8|@]|9|@$F|X|G|Y|1|Z]]|A|$]]|$1|H|3|I|5|6|7|10|8|@]|9|@]|A|$]]|$1|J|3|K|5|6|7|11|8|@]|9|@$F|12|G|13|1|14]]|A|$]]|$1|L|3|-4|5|6|7|15|8|@]|9|@]|A|$]]]|M|$N|$5|O|P|Q|A|$R|S]]|T|$5|O|P|Q|A|$R|K]]]]

your approach is good because yyyy-mm-dd hh:ii:ss can be compared as a string and get correct results, other date formats will fail

another option is to read this stackoverflow question 

<a href="https://stackoverflow.com/questions/2592501/compare-dates-in-java">How to compare dates in Java?</a>

and you should simply parse your strings and create Date or Calendar objects, depends on what you want to do , below is something I find useful

<a href="http://www.mkyong.com/java/java-how-to-get-current-date-time-date-and-calender/" rel="nofollow noreferrer">http://www.mkyong.com/java/java-how-to-get-current-date-time-date-and-calender/</a>

blocks|key|407907|text|关于|type|unstyled|depth|inlineStyleRanges|entityRanges|data|407908|++"999-01-01+00:00:00"

"10000-01-01+00:00:00"|code-block|syntax|javascript|407909|entityMap^0|0|0^^$0|@$1|2|3|4|5|6|7|I|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|J|8|@]|9|@]|A|$E|F]]|$1|G|3|-4|5|6|7|K|8|@]|9|@]|A|$]]]|H|$]]

what about 

<pre><code> "999-01-01 00:00:00"

"10000-01-01 00:00:00"
</code></pre>

blocks|key|189765|text|这不是一种好的做法，也不是一种代码的味道。|type|unstyled|depth|inlineStyleRanges|entityRanges|data|189766|你失去了语义上的正确和可读的代码。(以及可扩展性、时区和其他已经说过的正确的东西)|189767|你不会想要比较两个String对象，你想要比较两个Date对象-所以就这样做，比较两个Date对象。|offset|length|style|CODE|189768|如果您创建单元测试并测试您的比较方法，您将永远不会编写一个方法来在任何情况下都正确地比较2个"string"-dates，而不将它们转换为日期。|189769|entityMap^0|0|0|9|6|P|4|17|4|0|0^^$0|@$1|2|3|4|5|6|7|N|8|@]|9|@]|A|$]]|$1|B|3|C|5|6|7|O|8|@]|9|@]|A|$]]|$1|D|3|E|5|6|7|P|8|@$F|Q|G|R|H|I]|$F|S|G|T|H|I]|$F|U|G|V|H|I]]|9|@]|A|$]]|$1|J|3|K|5|6|7|W|8|@]|9|@]|A|$]]|$1|L|3|-4|5|6|7|X|8|@]|9|@]|A|$]]]|M|$]]

It is not good practice and a code smell.

You lose semantic correct and readable code. (and extensibility, timezones, and the other right things, that already had been said)

You don't want to compare two <code>String</code>s, you want to compare 2 <code>Date</code>s - so just do this, compare two <code>Date</code> objects.

If you create unit-tests and test your comparing method, you will never write a method that compares 2 "string"-dates correctly in every case, without converting them to dates.

blocks|key|407978|text|我的日期来自基于字符串的来源，格式总是YYYY-MM-DD，没有时区信息或其他复杂情况。因此，在比较一长串日期时，将它们作为字符串进行比较要比先将它们转换为日期对象更简单、更有效。|type|unstyled|depth|inlineStyleRanges|entityRanges|data|407979|这从来都不是问题，直到我在代码中犯了这个错误：|407980|boolean+past+=+(dateStart.compareTo(now)+==+-1);|code-block|syntax|javascript|407981|这给出了一些错误的结果，因为compareTo不仅返回值为-1、0或1。以下是简单的修复方法：|407982|boolean+past+=+(dateStart.compareTo(now)+<+0);|407983|我在这里加入了这个问题，因为这是我在试图找出我做错了什么时发现的一个问题。|407984|entityMap^0|0|0|0|0|0|0^^$0|@$1|2|3|4|5|6|7|Q|8|@]|9|@]|A|$]]|$1|B|3|C|5|6|7|R|8|@]|9|@]|A|$]]|$1|D|3|E|5|F|7|S|8|@]|9|@]|A|$G|H]]|$1|I|3|J|5|6|7|T|8|@]|9|@]|A|$]]|$1|K|3|L|5|F|7|U|8|@]|9|@]|A|$G|H]]|$1|M|3|N|5|6|7|V|8|@]|9|@]|A|$]]|$1|O|3|-4|5|6|7|W|8|@]|9|@]|A|$]]]|P|$]]

My dates are coming from a string-based source and are always formatted YYYY-MM-DD, without time zone info or other complications. So when comparing a long list of dates, it's simpler and more efficient to compare them as strings rather than to convert them to date objects first.

This was never a problem until I made this mistake in my code:

<pre><code>boolean past = (dateStart.compareTo(now) == -1);
</code></pre>

This was giving some incorrect results because compareTo doesn't only return values as -1, 0 or 1. This was the simple fix:

<pre><code>boolean past = (dateStart.compareTo(now) &lt; 0);
</code></pre>

I'm including this gotcha here because this is one of the SO questions I found when trying to figure out what I was doing wrong.

I'm getting two dates as String values and I wanted to check start time is earlier than the end time. I compare them as it is without converting them to date using <code>SimpleDateFormat</code>, like this:

<pre><code>String startTime = "2013-01-02 14:25:56";
String endTime = "2013-01-02 14:30:56";

if(endTime.compareTo(startTime) &gt; 0){
 System.out.println("End time is greater than start time");
}
</code></pre>

Is it really necessary to convert them to date and compare? Will I miss anything? Am I doing the right thing?

compare dates in String format

单元测试

我得到两个日期作为字符串值，我想检查开始时间是否早于结束时间。我不使用SimpleDateFormat将它们转换为日期，而是按原样进行比较，如下所示：String startTime = "2013-01-02 14:25:56";String endTime   = "2013-01-02 14:30:56";if(...

问比较字符串格式的日期
EN

社区

活动

资源

关于

腾讯云开发者

热门产品

热门推荐

更多推荐

问比较字符串格式的日期EN

社区

活动

资源

关于

腾讯云开发者

热门产品

热门推荐

更多推荐

问比较字符串格式的日期
EN