DelayQueueMain.java

import java.util.concurrent.DelayQueue;
import java.util.concurrent.Delayed;
import java.util.concurrent.TimeUnit;

import static java.lang.System.currentTimeMillis;
import static org.apache.commons.lang.time.DateUtils.MILLIS_PER_SECOND;

public class DelayQueueMain {

    public static void main(String[] args) throws InterruptedException {
        DelayQueue<Conference> conferences = new DelayQueue<Conference>();
        conferences.add(new Conference(5));
        conferences.add(new Conference(10));
        conferences.add(new Conference(15));

        while(!conferences.isEmpty()) {
            System.out.println("Waiting for conference...");
            System.out.println(conferences.poll(1, TimeUnit.MINUTES));
        }
    }
}

class Conference implements Delayed {

    private long startTime;

    public Conference(long delayInSeconds) {
        this.startTime = currentTimeMillis() + delayInSeconds * MILLIS_PER_SECOND;
    }

    @Override
    public int compareTo(Delayed o) {
        Conference c = (Conference) o;
        return startTime < c.startTime ? -1 : startTime == c.startTime ? 0 : 1;
    }

    @Override
    public long getDelay(TimeUnit unit) {
        return startTime - currentTimeMillis();
    }

}