public interface Command { public void execute(); //public void undo(); } public class NullCommand implements Command{ @Override public void execute() { } } /*버튼 하나로 여러 개를 켜고 싶을 때*/ public class enterCommand implements Command { Light myLight; TV myTv; enterCommand(Light light, TV tv){ this.myLight = light; this.myTv = tv; } @Override public void execute() { myLight.on(); myTv.on(); } } public c..