import java.io.Serializable;
import java.util.Arrays;
import java.util.List;

public class MainApp {
    public static void main(String[] args) {
        AppLogger logger = new AppLogger();
        Thread srv1 = initService(logger, "MainService");
        Thread srv2 = initService(logger, "ReportService");
        Thread srv3 = initService(logger, "ReportGenerator");
        Thread srv4 = initService(logger, "MailService");
        Thread srv5 = initService(logger, "NotificationService");

        List<Thread> services = Arrays.asList(srv1, srv2, srv3, srv4, srv5);
        services.forEach(service -> service.start());

        services.forEach(service -> {
            try {
                service.join();
            } catch (InterruptedException e) {
                throw new RuntimeException(e);
            } catch (Exception e) {
                e.printStackTrace();
            }
        });
        //some code
        System.out.println(logger.printData());
    }

    private static Thread initService(AppLogger logger, String name) {
        return new Thread(logger::appendData, name);
    }
}

public class AppLogger {
    private final StringBuilder builder = new StringBuilder();

    public void appendData() {
        InitEvent event = new InitEvent("DefEvent");
        //some code
        for (int i = 0; i < 10; i++) {
            builder.append(event.getName() + i);
        }
    }

    public String printData() {
        return builder.toString();
    }
}

public class InitEvent implements Serializable {
    private String name;

    public InitEvent(String name) {
        this.name = name;
    }

    public InitEvent() {

    }

    public String getName() {
        return name;
    }

    public void setName(String name) {
        this.name = name;
    }
}