java.util.Observerを使用したメモ

import java.util.Observer;
import java.util.Observable;

public class Main {
    public static void main(String[] args) {
        Sample sample = new Sample();
        sample.addObserver(new Observer() {
            @Override
            public void update(Observable observe, Object o) {
                System.out.println("changed: " + ((Sample)o).getName());
            }
        });
        sample.setName("hoge");
        sample.setName("fuga");
    }

    public static class Sample extends Observable {

        private String name;

        public String getName() {
            return name;
        }

        public void setName(String name) {
            this.name = name;
            // hasChangedメソッドの返り値がsetChangedを行った後はtrueになる
            setChanged();
            notifyObservers(this);
        }
    }
}