End of month calculations?

Question

Just wondering if any know of an elegant solution for the following. If I have 30 June 2009 and I add a month I want it to go to 31 July 2009, not the 30 July 2009. This logic is based on the fact that the 30 June 2009 was the end of the month of June and when I add a month I want to go to the end of the next month. But if I have 29 June 2009 and I add a month it should go to 29 July 2009. Note I need to be able to add any number of months and I need to take into account leap years. Also I know the logic here is questionable but it is a business requirement that works with end of month contracts going to the end of the month for a month in the future. I have thought of several solution but none that are very elegant. Hence I was thinking someone might have a better way. Cheers Anthony

Answer 1

Here's part of your solution:

private MonthEnd( int month, int year)

{

int iReturn=-1;

switch ( month)

{

//30 days has september, April, June, and November

case 9:

case 4:

case 6:

case 11:

{

iReturn = 30;

break;

}

case 1:

case 3:

case 5:

case 7:

case 8:

case 10:

case 12:

{

iReturn = 31;

break;

}

case 2: //February : leap year

{

if (

((y % 4)==0) && ((y % 1000) != 0)

)

{

iReturn = 29;

}

else

{

iReturn = 28;

}

break;

}

default

{

System.out.println(" invalid month ");

nreak;

}

} //switch

return( iReturn);

} //MonthEnd

So if your input date is end of month, you can easily find the number of days at the end of the next month using this function twice: once to check if your input date is in fact the last day of the month and if so, the end of month for the next month. Otherwise, you just increment your month number and you're set.