How to Calculate the Number of Days Between a Given Date Range in Java Code

You can calculate the number of days within known dates.

Calculating the number of days within a date range is a standard operation required by many computer programs. Java supports many varieties of formats and calculations on dates and times, through classes and methods in the Java standard libraries.

Instructions

1. Include the following line at the beginning of your Java code:

   import java.util.*;

2. Create objects of the GregorianCalendar library class for the dates at the beginning and at the end of the range, as in the following sample code:

   GregorianCalendar initialDate = new GregorianCalendar(2010,Calendar.MAY,20);

   GregorianCalendar finalDate = new GregorianCalendar(2011,Calendar.JUNE,4);

   Replace the dates in the example -- May 20, 2010 and June 4, 2011 -- with the dates of your choice.

3. Compute the number of milliseconds elapsed between the two dates by using the .getTime() method, as in the following sample code:

   long millisElapsed;

   millisElapsed = (finalDate.getTime()).getTime() - (initialDate.getTime()).getTime();

4. Convert milliseconds to days, as in the following sample code:

   int dayElapsed = millisElapsed / (24 * 60 * 60 * 1000);

   After executing this line, variable "dayElapsed" will contain the number of days in the date range.

References

• Oracle: Java: Class Date