I am trying to prevent the time user provides is not a time in the past.

String userDate= request. getParameter("date);//yyyy-mm-dd
String userTime= request.getParameter("time);//hh:mm (24 hour notation)
DateFormat df= new SimpleDateFormat("yyyy-dd-mm hh:mm");
Date userDateTime=df.parse(userDate+ " " + userTime);

Date serverTime= new Date();
if(serverTime.after(userDateTime){
return false;
}

This works well. But now I have to consider the user's time zone, and this is where I hesitate.
The time zone user provides is in the format +7:30, -5 , 0 etc format from UTC.
Is there any simple way to accomodate the time zone?
or else I have to convert the user timezone input from +7:30 to 0700, which is the DateFormat requires in java for time zone. I dont want to do a lot of parsing. But is it the only way to do it? How are you guys been doing it?

FROM SOURCE http://www.exampledepot.com/egs/java.util/GetTimeOtherZone2.html




// Given a local time of 10am, get the time in Japan
// Create a Calendar object with the local time zone
Calendar local = new GregorianCalendar();
local.set(Calendar.HOUR_OF_DAY, 10); // 0..23
local.set(Calendar.MINUTE, 0);
local.set(Calendar.SECOND, 0);

// Create an instance using Japan's time zone and set it with the local UTC
Calendar japanCal = new GregorianCalendar(TimeZone.getTimeZone("Japan"));
japanCal.setTimeInMillis(local.getTimeInMillis());

// Get the foreign time
int hour = japanCal.get(Calendar.HOUR); // 3
int minutes = japanCal.get(Calendar.MINUTE); // 0
int seconds = japanCal.get(Calendar.SECOND); // 0
boolean am = japanCal.get(Calendar.AM_PM) == Calendar.AM; //true


// Given a time of 10am in Japan, get the local time
japanCal = new GregorianCalendar(TimeZone.getTimeZone("Japan"));
japanCal.set(Calendar.HOUR_OF_DAY, 10); // 0..23
japanCal.set(Calendar.MINUTE, 0);
japanCal.set(Calendar.SECOND, 0);

// Create a Calendar object with the local time zone and set
// the UTC from japanCal
local = new GregorianCalendar();
local.setTimeInMillis(japanCal.getTimeInMillis());

// Get the time in the local time zone
hour = local.get(Calendar.HOUR); // 5
minutes = local.get(Calendar.MINUTE); // 0
seconds = local.get(Calendar.SECOND); // 0
am = local.get(Calendar.AM_PM) == Calendar.AM; // false

Thanks thapap,
I actually dont know the time zone place, I only know the offset. So I cant use getTimeZone("Japan");
I have the offset string, and I want to convert it to a timezone. Thats my problem in short. I can do it by parsing the string, and that can be error-prone depending on the user input.

you can use

You can use the getAvailableIDs method to iterate through all the supported time zone IDs. You can then choose a supported ID to get a TimeZone. If the time zone you want is not represented by one of the supported IDs, then a custom time zone ID can be specified to produce a TimeZone. The syntax of a custom time zone ID is:

CustomID:
GMT Sign Hours : Minutes
GMT Sign Hours Minutes
GMT Sign Hours
Sign: one of
+ -
Hours:
Digit
Digit Digit
Minutes:
Digit Digit
Digit: one of
0 1 2 3 4 5 6 7 8 9


Hours must be between 0 to 23 and Minutes must be between 00 to 59. For example, "GMT+10" and "GMT+0010" mean ten hours and ten minutes ahead of GMT, respectively.

read more here http://java.sun.com/j2se/1.4.2/docs/api/java/util/TimeZone.html

Thanks. I got it working.

WASTE OF TIME

Ha ha... Revenge??