public class Main {
public static void main(String... args) {
    Zuhoerer Maria = new Zuhoerer("Maria");
    Zuhoerer Sepp = new Zuhoerer("Sepp");
    Zeitansager.sagAn();
}
}

class Zuhoerer {
private String name;
private String Ansager;

Zuhoerer(String name) {
    this.name = name;
}

private void setAnsager(String datumstring) {
    Ansager = datumstring;
}

void update() {
    setAnsager(Zeitansager.getZeit());
    Zeitansager.schreibeEin(name);
    System.out.println(name + " hat gerade die die Zeitansage gehört:
[Datum/Uhrzeit]: " + Ansager);
    Zeitansager.trageAus(name);
}
}

class Zeitansager {
private static String datumString;
private static ArrayList<String> abonnenten;

Zeitansager(String datumString) {
    Zeitansager.datumString = datumString;
    abonnenten = new ArrayList<>();
    }

    static void schreibeEin(String name) {
    abonnenten.add(name);
    }

    static void trageAus(String name) {
        abonnenten.remove(name);
    }


static void sagAn() {
    SimpleDateFormat sdf = new SimpleDateFormat("dd.MM.YYYY' 'HH:mm:ss");
    String datum = sdf.format(new Date());
    datumString = datum;
    for (int i=1; i <= abonnenten.size(); i++) {
        abonnenten.update();
    }
}
static String getZeit() {
    return datumString;
}
}