Timestamp calculation function

I am trying to write Java code as a part of my project to get current time for a process and then i need to add a fixed timeout period to it. This new time has to be compared with my above currenttime and take decision based on that. I am not able to add time to th开发者_如何学编程e currenttime and compare it. Can anyone help me by suggesting a way?

This is my code:

   public class SessionDetails
    {
     public String getCurrentUtcTimestamp() {
        TimeZone timeZone = TimeZone.getTimeZone("UTC:00");
        DateFormat dateFormat = DateFormat.getDateTimeInstance();
        dateFormat.setTimeZone(timeZone);
        timeStamp = dateFormat.format(new Date());
        return timeStamp;
    }
     public void createSession()
         {
           int value = getsession();
           String timeStamp = getCurrentUtcTimestamp() ;
           System.out.println("New session Details :");
           System.out.println("session value:" + value);
           System.out.println("Time of creation :" + timeStamp );
         }
    public boolean checkTimeout(int value)
        {   
            private static long c_Timeout = 10000;
            String currentTime =  getCurrentUtcTimestamp() ;
            if ( currentTime > timeStamp + c_Timeout )   //failing to implement this logic efficiently .please do suggest a way.Thanku..
             System.out.println("Sorry TimeOut");
           else 
             System.out.println("Welcome");

        }
 }

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Do you really need to store the timestamp as a string? I would suggest using a long, e.g. the result of calling System.currentTimeMills()... then format that into a string only for diagnostic purposes. Comparing long values is very easy :)

Alternatively, use Joda Time and keep the timestamps as Instant values. That will make formatting easier, and you can use isAfter, isAfterNow etc for comparisons.

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You never want to use String to store/handle precise dates.

Usually you want to use Date, Calendar or even a more modern Java Date/Time API such as Joda Time or JSR-310 (reference implementation here).

If you simply want to use simple local timestamps, then a long might be sufficient:

long currentTime = System.currentTimeMillis();

The advantage of a long is that you can use all the normal operations (addition, subtraction, equality checks, less-than-check) as you would do with any other numeric primitive type.

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Just Simplyfying your method returning long

public long getCurrentUtcTimestamp() 
{
    TimeZone utc = TimeZone.getTimeZone("UTC");
    Calendar calendar = Calendar.getInstance(utc);
    return calendar.getTimeInMillis();
}