import java.util.ArrayList;

import java.util.List;

class Originator {

private String state;

public void setState(String state){

this.state = state;

}

public String getState(){

return state;

}

public Memento saveStateToMemento(){

return new Memento(state);

}

public void getStateFromMemento(Memento Memento){

state = Memento.getState();

}

}

class Memento {

private String state;

public Memento(String state) {

this.state=state;

}

public String getState() {

return state;

}

}

class Caretaker {

private List<Memento> mementoList = new ArrayList<Memento>();

public void add(Memento state){

mementoList.add(state);

}

public Memento get(int index){

return mementoList.get(index);

}

}

class MementoPatternDemo {

public static void main(String[] args) {

Originator originator = new Originator();

Caretaker careTaker = new Caretaker();

originator.setState("State #1");

careTaker.add(originator.saveStateToMemento());

originator.setState("State #2");

careTaker.add(originator.saveStateToMemento());

originator.setState("State #3");

careTaker.add(originator.saveStateToMemento());

originator.setState("State #4");

System.out.println("Current State: " + originator.getState());

originator.getStateFromMemento(careTaker.get(0));

System.out.println("First saved State: " + originator.getState());

originator.getStateFromMemento(careTaker.get(1));

System.out.println("Second saved State: " + originator.getState());

originator.getStateFromMemento(careTaker.get(2));

System.out.println("Third saved State: " + originator.getState());

}

}