To get previous day timestamp of a timestamp value in java

Question

Hi,
I have a timestamp variable, say settledTimeStamp which is passed as a runtime argument to a query. I should also send another timestamp variable say previousTimeStamp whose value should be previous day timestamp, ie for settledTimeStamp.
For example,
Todays date= May 9th 2008.
say settledTimeStamp to May 7th 2008.
I should get the timestamp value for previous day to SettleDate i.e May 6th, 2008.
I am showing this as an example because I tried with Calendar options too but it takes current timestamp and gives previous days timestamp which is not the same as I required. Like it returns May 8th as my previousTimeStamp if I work with Calendar options....
Can anyone help me on this?

Answer 1

An object of the Calendar class represents a specific point in time. The fields, such as DAY_OF_MONTH, allow you to access meaningful parts of that specific point in time and use them. Calendar.DAY_OF_MONTH is a field, and it doesn't represent the "current day" or any particular point in time at all. It's used to ask a particular Calendar object what its DAY_OF_MONTH is.
import java.util.Calendar;
public class Test {
     public static void main(String[] args) {
          Calendar cal = Calendar.getInstance();
          cal.setTimeInMillis(99999999999L);
          int year = cal.get(Calendar.YEAR); //cal, what is your YEAR?
          System.out.println(year);
          int dayOfWeek = cal.get(Calendar.DAY_OF_WEEK); //cal, what is your DAY_OF_WEEK?
          System.out.println(dayOfWeek);
          boolean inApril = Calendar.APRIL == cal.get(Calendar.MONTH); //cal, are you in the month of APRIL?
          System.out.println(inApril );
          System.out.println(cal); //cal, tell me all about yourself
}Really, the documentation can do a better job explaining it than I can. Read it. And there are numerous Calendar and Date tutorials all over the internet. Date processing in java is not the easiest thing, so it can take a bit of getting used to, but you will have to read the documentation and write code yourself to understand it.
Oh, and you mark your question as answered and then dispense duke stars to posts you felt were helpful. I don't think people here really care much about them.