如何将变量参数传递给观察者？

public interface Observer {
    void update(Object parameter);
}

public class ConcreteObserver implements Observer {
    @Override
    public void update(Object parameter) {
        // 处理接收到的变量参数
    }
}

public interface Observable {
    void addObserver(Observer observer);
    void removeObserver(Observer observer);
    void notifyObservers(Object parameter);
}

public class ConcreteObservable implements Observable {
    private List<Observer> observers = new ArrayList<>();

    @Override
    public void addObserver(Observer observer) {
        observers.add(observer);
    }

    @Override
    public void removeObserver(Observer observer) {
        observers.remove(observer);
    }

    @Override
    public void notifyObservers(Object parameter) {
        for (Observer observer : observers) {
            observer.update(parameter);
        }
    }
}

public class Main {
    public static void main(String[] args) {
        ConcreteObservable observable = new ConcreteObservable();
        Observer observer1 = new ConcreteObserver();
        Observer observer2 = new ConcreteObserver();

        observable.addObserver(observer1);
        observable.addObserver(observer2);

        // 变量参数发生变化
        Object parameter = new Object();
        observable.notifyObservers(parameter);
    }
}