import java.util.concurrent.CountDownLatch;


class Arbeid implements Runnable {
    private final CountDownLatch ferdigBarriere;

    Arbeid(CountDownLatch ferdig) {
        ferdigBarriere = ferdig;
    }

    public void run(){
        System.out.println("Gjoer arbeid");
        gjorArbeid();
        System.out.println("Ferdig");
        ferdigBarriere.countDown();
    }

    public void gjorArbeid() {
        // kunne gjort noe her
    }
}

class TestCountDown {
    public static void main(String[] args) {
        int antTraader = 5;
        CountDownLatch ferdigBarriere = new CountDownLatch(antTraader);
        for (int i = 0; i < antTraader; i++) {
            new Thread(new Arbeid(ferdigBarriere)).start();
        }
        try {
            ferdigBarriere.await(); // venter paa alle traadene
        } catch (InterruptedException e) {}
        System.out.println("Alle er ferdige!");
    }
}