[ Java 代碼範本 ] Joda - Calculate the number of days between two dates

Question 
In Java, I want to calculate the number of days between two dates as Date type. 

How-To 
Well to start with, you should only deal with them as strings when you have to. Most of the time you should work with them in a data type which actually describes the data you're working with. I would recommend that you use Joda Time, which is a much better API than Date/Calendar. It sounds like you should use theDays type in this case. You can then use: 

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1. package test  
2.   
3. import java.text.SimpleDateFormat  
4.   
5. import org.joda.time.DateTime;  
6. import org.joda.time.Days;  
7.   
8.   
9. String date1Str = '2015/05/03'  
10. String date2Str = '2015/06/10'  
11.   
12. SimpleDateFormat sdf = new SimpleDateFormat("yyyy/MM/dd")  
13.   
14. Date d1 = sdf.parse(date1Str)  
15. Date d2 = sdf.parse(date2Str)  
16.   
17. DateTime f = new DateTime(d1.getTime())  
18. DateTime t = new DateTime(d2.getTime())  
19.   
20. printf("Between %s ~ %s = %d days!\n", date1Str, date2Str, Days.daysBetween(f, t).getDays()+1)  

Execution result: 

Between 2015/05/03 ~ 2015/06/10 = 39 days!

Supplement 
* Joda Online API 
* Calculating the difference between two Java date instances