import java.util.Set; import java.util.HashSet; public class ConcreteSubject implements Subject { private Set<Observer> observers; public enum Status { NORMAL, ERROR } private Status status; public void setStatus(Status status) { this.status = status; notifyObservers(); // status フィールドを更新したら Observer に通知するようにしておきます } public String getStatus() { return status.toString(); } public ConcreteSubject()
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