fork download
copy 
  1. import java.io.*;
  2. import java.lang.*;
  3. import java.text.*;
  4. import java.util.*;
  5.  
  6. class Ideone
  7. {
  8. 	public static int dayOfWeek(int year, int month, int day)
  9. 	{
  10. 		day += month < 3 ? year-- : year - 2;
  11. 		return ((((23 * month) / 9) + day + 4 + (year / 4)) - (year / 100) + (year / 400)) % 7;
  12.     }
  13.  
  14. 	public static void main (String[] args) throws java.lang.Exception
  15. 	{
  16. 		DateFormat df = new SimpleDateFormat("yyyy-MM-dd");
  17.  
  18. 		Calendar start = Calendar.getInstance();
  19. 		start.setTime(df.parse("1900-01-01"));
  20. 		Calendar end = Calendar.getInstance();
  21. 		end.setTime(df.parse("2020-01-01"));
  22.  
  23. 		for (Date date = start.getTime(); start.before(end); start.add(Calendar.DATE, 1), date = start.getTime())
  24. 		{
  25. 			int expected = date.getDay();
  26. 			int actual = dayOfWeek(date.getYear() + 1900, date.getMonth() + 1, date.getDate());
  27. 			if (expected != actual)
  28. 			{
  29. 				throw new RuntimeException("expected: " + expected + ", actual: " + actual);
  30. 			}
  31. 		}
  32. 	}
  33. }
Success #stdin #stdout 0.27s 321600KB
comments (?)
stdin
copy 
Standard input is empty
stdout
copy 
Standard output is empty
https://ideone.com/te3ywm
language:
Java (HotSpot 12)
created:
10 years ago
visibility:
public

Share or Embed source code

Discover > Sphere Engine API

The brand new service which powers Ideone!

Discover > IDE Widget

Widget for compiling and running the source code in a web browser!