Question

I have a database field where date is stored as DD/MM/YYYY format. Now what I want to do is to see if today date = stored date – 1. Basically if today is the day before the end date. Based on that I will do some action…

example of format:

10/02/2012

There is formatting issue here because am using this:

Date todayDate;

And the stored date is VARCHAR2 in DB. Am assuming I would have to convert the retrieved date to Date regular format, or something like that. Help would be appreciated.

Update:

                currentEndDate =  rset.getString("ENDDATE");
                endDate = (Date)formatter.parse(currentEndDate);
                /*Check if end date = today date - 1*/
                Calendar cal = Calendar.getInstance();
                //set to end date
                cal.setTime(endDate);
                //end date - 1
                cal.add(Calendar.DATE, -1); 
                Date today;

Now this is what I have..I am trying here to get the end date -1 so I did that using add() function. Now How can I check if end-date – 1 == today date or not? because when I tried :

if(today.equals(cal.add(Calendar.date, -1)))

it said void return from the add function.
Thanks,

Answer 1

You need to turn the String into a date. You can do this in your query or after you get the string result:

Option 1: turn it into a Date type in your query:

SELECT TO_DATE("COLNAME", 'MM/DD/YYYY') FROM "MYTABLE"

Option 2: turn it into a Date type after you get the string:

String date_from_db;
SimpleDateFormat sdf = new SimpleDateFormat("MM/dd/yyyy");
Date date = sdf.parse(date_from_db);

Then you can see if the current time (new Date()) is between the retrieved date and a day before that. If you want to handle all corner cases including leap seconds, you’ll have to use a Calendar, but if you’re okay with leaving out leap seconds then it’ll be fine to just subtract 24*60*60*1000 milliseconds from your db date.

You can’t directly compare a Date and a Calendar as per the API documentation:

…objects are equal if and only if the getTime method returns the same long value for both

Also, Calendar‘s equals() won’t work:

The result is true if and only if the argument is a Calendar object of the same calendar system that represents the same time value

Simple solution: use the Calendar‘s getTime() method, which returns a Date object which will readily compare with other dates using equals(), after(), and before().

Or in code:

cal.add(Calendar.DAY, -1);
if(cal.getTime().equals(new Date())) { ... }

You could also instantiate another Calendar and use its setTime(), but that seems less efficient.