<p>Originally I am looking for a solution in Actionscript. The point of this question is the algorithm, which detects the exact Minute, when a clock has to switch the Daylight Saving Time. </p>

<p>So for example between the 25th and the 31th of October we have to check, if the actual date is a sunday, it is before or after 2 o'clock...</p>

There is no real algorithm for dealing with Daylight Saving Time. Basically every country can decide for themselves when -and if- DST starts and ends. The only thing we can do as developers is using some sort of table to look it up. Most computer languages integrate such a table in the language.
In Java you could use the
```
inDaylightTime
```
method of the
TimeZone
class. If you want to know the exact date and time when DST starts or ends in a certain year, I would recommend to use
Joda Time
. I can't see a clean way of finding this out using just the standard libraries.
The following program is an example: (Note that it could give unexpected results if a certain time zone does not have DST for a certain year)
```
```
import org.joda.time.DateTime;
import org.joda.time.DateTimeZone;

public class App {
    public static void main(String[] args) {
        DateTimeZone dtz = DateTimeZone.forID("Europe/Amsterdam");

        System.out.println(startDST(dtz, 2008));
        System.out.println(endDST(dtz, 2008));
    }

    public static DateTime startDST(DateTimeZone zone, int year) {
        return new DateTime(zone.nextTransition(new DateTime(year, 1, 1, 0, 0, 0, 0, zone).getMillis()));
    }

    public static DateTime endDST(DateTimeZone zone, int year) {
        return new DateTime(zone.previousTransition(new DateTime(year + 1, 1, 1, 0, 0, 0, 0, zone).getMillis()));
    }
}
```
```