Order.java

public class Order {
    State unpaidState;
    State paidState;
    State shippedState;
    State deliveredState;

    State state = unpaidState;

    public Order() {
        unpaidState = new UnpaidState(this);
        paidState = new PaidState(this);
        shippedState = new ShippedState(this);
        deliveredState = new DeliveredState(this);
    }

    public State getUnpaidState() {
        return unpaidState;
    }

    public State getPaidState() {
        return paidState;
    }

    public State getShippedState() {
        return shippedState;
    }

    public State getDeliveredState() {
        return deliveredState;
    }

    public void verifyCreditCard(String info) {
        state.verifyCreditCard(info);
    }

    public void ship() {
        state.ship();
    }

    public void orderDelivered() {
        state.orderDelivered();
    }

    public void setState(State state) {
        this.state = state;
    }
}