import java.util.concurrent.CountDownLatch;

class Arbeider implements Runnable {
    private CountDownLatch ferdigSignal;

    public Arbeider(CountDownLatch ferdig) {
        ferdigSignal = ferdig;
    }
    @Override
    public void run() {
        try {
            System.out.println("Gjor arbeid");
            gjorArbeid();
            ferdigSignal.countDown();
        }
        catch (InterruptedException e) {

        }
    }
    public void gjorArbeid() throws InterruptedException {}
}
class TestCountdown {
    public static void main(String[] args) throws InterruptedException {
        int antTraader = 5;
        CountDownLatch ferdigSignal = new CountDownLatch(antTraader);
        for (int i = 0; i < antTraader; i++) {
            Thread t = new Thread(new Arbeider(ferdigSignal));
            t.start();
        }
        ferdigSignal.await();
        System.out.println("Alle er ferdige!");
    }
}