How do I calculate today's date minus one month?

[laredotornado]

Hi,

I'm using Java 1.5. How do I get a java.util.Date exactly one month
before today's date? I thought about converting todays date to
milliseconds and then subtracting a value, but not every month has the
same number of milliseconds.

- Dave

 

[Joshua Cranmer]

Hi,

I'm using Java 1.5. How do I get a java.util.Date exactly one month
before today's date? I thought about converting todays date to
milliseconds and then subtracting a value, but not every month has the
same number of milliseconds.

Month as in "30 days" or "this day in the last calendar month"? What is
exactly one month before December 31? March 29?

Here's some code using Calendar that treats the equivalent of "November
31" as "November 30":

Calendar cal = Calendar.getInstance();
cal.setTime(date);
cal.add(Calendar.MONTH, -1);
date = cal.getTime();

 

[Tim Slattery]

Hi,

I'm using Java 1.5. How do I get a java.util.Date exactly one month
before today's date? I thought about converting todays date to
milliseconds and then subtracting a value, but not every month has the
same number of milliseconds.

Look at the add method of GregorianCalendar, that will do what you
need.

 

[laredotornado]

Look at the add method of GregorianCalendar, that will do what you
need.

What I meant by exactly one month is if today is "10-3-2008", one
month ago was "9-3-2008". Of course, I don't know what one month ago
means for "7-31-2008". But I have used GregorianCalendar's add
method, per Tim's suggestion

this.m_throughDate = new Date();
GregorianCalendar gc = new
GregorianCalendar(this.m_throughDate.getYear(),
this.m_throughDate.getMonth(), this.m_throughDate.getDate());
gc.add(Calendar.MONTH, -1);
this.m_fromDate = gc.getTime();

Thanks, - Dave

 

[Roedy Green]

I'm using Java 1.5. How do I get a java.util.Date exactly one month
before today's date? I thought about converting todays date to
milliseconds and then subtracting a value, but not every month has the
same number of milliseconds.

That is trivial with BigDate. See TestDate examples. With Calendar is
is a bit uglier. See http://mindprod.com/products1.html#COMMON11
http://mindprod.com/jgloss/calendar.html