Java 如何比较字符串格式的两个日期？
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How to compare two dates in String format?
提问by Klausos Klausos
What is the easiest way to compare two dates in String format? I would need to know if date1comes after/before date2.
以字符串格式比较两个日期的最简单方法是什么？我需要知道是否date1在之后/之前date2。
String date1 = "2015-12-01";
String date2 = "2015-12-31";
采纳答案by Micha? Szyd?owski
For a more generic approach, you can convert them both to Dateobjects of a defined format, and then use the appropriate methods:
对于更通用的方法，您可以将它们都转换Date为定义格式的对象，然后使用适当的方法：
SimpleDateFormat format = new SimpleDateFormat("yyyy-MM-dd");
Date date1 = format.parse(date1);
Date date2 = format.parse(date2);
if (date1.compareTo(date2) <= 0) {
System.out.println("earlier");
}
回答by Danil Gaponov
In this very case you can just compare strings date1.compareTo(date2).
在这种情况下，您可以只比较字符串date1.compareTo(date2)。
EDIT: However, the proper way is to use SimpleDateFormat:
编辑：但是，正确的方法是使用SimpleDateFormat：
DateFormat f = new SimpleDateFormat("yyyy-mm-dd");
Date d1 = f.parse(date1, new ParsePosition(0));
Date d2 = f.parse(date2, new ParsePosition(0));
And then compare dates:
然后比较日期：
d1.compareTo(d2);
The comparison will return negative value if d1is before d2and positive if d1is after d2.
如果d1在之前d2，比较将返回负值，如果d1在之后则返回正值d2。
回答by Atais
With JodaTime, simply:
使用 JodaTime，只需：
DateTime d1 = DateTime.parse(date1);
DateTime d2 = DateTime.parse(date2);
Assert.assertTrue(d1.isBefore(d2));
Assert.assertTrue(d2.isAfter(d1));
回答by LBes
You can simply convert your string to dates:
您可以简单地将字符串转换为日期：
Date date1 = sdf.parse("2015-12-01");
Date date2 = sdf.parse("2010-01-01");
Then the comparison is done like: if(date1.after(date2)){ System.out.println("Date1 is after Date2"); }
然后比较是这样完成的： if(date1.after(date2)){ System.out.println("Date1 is after Date2"); }
if(date1.before(date2)){
System.out.println("Date1 is before Date2");
}
if(date1.equals(date2)){
System.out.println("Date1 is equal Date2");
}
If I remember correctly there's a ParseExceptionto handle
如果我没记错的话，有一个ParseException要处理的
回答by Abhijit Kumbhar
Yes you can compare this as follows:
是的，您可以按如下方式进行比较：
Date date1 = new Date();
Date date2 = new Date();
if(date1.before(date2)){
// statement
}
if(date1.after(date2)){
// statement
}
回答by akhil_mittal
I would advise you to convert them to Dateobjects.
我建议您将它们转换为Date对象。
String date1 = "2015-12-01";
String date2 = "2015-12-31";
SimpleDateFormat sdf = new SimpleDateFormat("yyyy-MM-dd");
System.out.println(sdf.parse(date1).before(sdf.parse(date2)));
Comparing them like:
比较它们，例如：
if(date2 .compareTo(date1) > 0){
System.out.println(" ---- ");
}
is not an ideal option (date1 and date2 are strings) as it loses the flexibility and can lead to its own share of problems.
不是一个理想的选择（date1 和 date2 是字符串），因为它失去了灵活性并可能导致其自身的问题。
