State Design Pattern implementation.

[chets patel]

I am trying to learn State design pattern. I took example of Order being placed and having different state. I have implemented it. But I am not sure it is correct way or not. Please check below code and help in that case.

public interface OrderState {

        void performAction(Context context);

        void setNextState(Context context);

}

public class InitialOrderState implements OrderState{

	@Override
	public void performAction(Context context) {
		System.out.println("Perform initial state operations.");
		setNextState(context);
	}

	@Override
	public void setNextState(Context context) {
		context.setCurrentState(Context.STATE_DELIVERED);
	}

}

public class DeliveredOrderState implements OrderState {

	@Override
	public void performAction(Context context) {
		System.out.println("Perform delivered state operations");
		setNextState(context);
	}

	@Override
	public void setNextState(Context context) {
		context.setCurrentState(Context.STATE_CLOSED);
	}

}


public class Context {
	public static final OrderState STATE_INITIAL = new InitialOrderState();
	
	public static final OrderState STATE_DELIVERED = new DeliveredOrderState();
	
	public static final OrderState STATE_CLOSED = new ClosedOrderState();
	
	private OrderState currentState;
	
	public Context(OrderState orderState) {
		this.currentState = orderState;
	}

	public OrderState getCurrentState() {
		return currentState;
	}

	public void setCurrentState(OrderState currentState) {
		this.currentState = currentState;
	}
	
	public OrderState getInitialState() {
		return STATE_INITIAL;
	}
	
	public OrderState getDeliveredState() {
		return STATE_DELIVERED;
	}
	
	public static Context getOrderStateFromState(String state) {
		if ("Initial".equalsIgnoreCase(state)) {
			return new Context(STATE_INITIAL);
		} else {
			return new Context(STATE_DELIVERED);
		}
	}
}

From my client code I will get the context object depending on state.

       public void createOrder() {
             Context context = Context.getOrderStateFromState("Initial");
             OrderState initialState = new InitialOrderState();
             initialState.performAction(context);
             saveOrderInDatabase();
       }

       public void deliverOrder() {
             Order order = retrieveOrderFromDB();
             Context context = Context.getOrderStateFromState(order.getState());
             DeliveredOrderState deState = new DeliveredOrderState();
             deState.performAction(context);
             saveOrderInDatabase();              
 
      }

Please let me know if above implementation is correct?
Thanks in advance.