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Move the "adding dough" to plain pizza class then the video is perfect!

10 years later and this video is still one of the easiest to follow and best videos on a design pattern I've seen so far! Thank you!

I'm happy they have been able to help you :) I decided a long time ago that I wanted to make long videos, but I also wanted them to be interesting and keep the viewers attention. I'm starting to really like the final results as of late. It has been very fulfilling to work at improving my teaching style. Thanks for giving the videos a look!

Thank you :) I'm working from 6 different books to make this tutorial. I'll cover everything in the GOF book, but probably in completely different ways. I'm glad you are enjoying the tutorial

You're very welcome :) Think of those classes that extend ToppingDecorator as if they are layering on functionality to the Pizza composite field in the ToppingDecorator object. So, first you create the Pizza object and then add additional functionality to getDescription and getCost using the toppings. Here is another tutorial on decorator that may help further newthinktank. com/2013/02/code-refactoring-16/

I have all of the diagrams on my site. There is a link in the description for the video. I hope it helps

You're very welcome :) I'm doing my best to cover the more complicated topics in programming. I'm glad people are finding them useful

Thank you for watching :) I'm glad to help

I probably could have come up with a more specific optimized way to present this pattern. The ToppingDecorator could have been more simplified and then the ingredients could have done most anything. In videos I have to find an example that both demonstrates the pattern while keeping everything as simple as possible. Sometimes I get a great example and other times not so much. Sorry about that

I'm just happy that you find it useful :) Thanks for the kind words. It is just a fun hobby of mine and I expect nothing in return

It is very nice to be able to clear up a subject when others haven't helped! Thank you :)

You're very welcome :) Thank you for checking them out

Thank you :) i did my best with them. I found an answer for your question that I agree with here: stackoverflow. com/questions/2166632/can-you-remove-a-decorator

Thank you :) I do my best to cover complicated topics in easy to understand ways. I'm glad you liked it

I read this pattern in Gang of Four today, was trying to figure out what the main method would end up looking like, very glad I found this video. None of my classes for my B.S. CompSci covered this stuff and I'm finding it very important for my job now.

Thank you for taking the time to tell me I was able to help :) That is very much appreciated!

I love this, thank you so much! It really helps to hear this concepts from someone rather that read boring books a thousand times for each pattern. It's really cool that you do this without expecting money or any type of retribution what so ever.

Thank you :) I like covering niche topics that everyone else avoids

Thanks, it's a great video explaining the concept very well. One thing that bothers me about commonly used patterns in Java is that they are often un-intuitive and do not reflect the real world as well as they could. I think the Decorator pattern is one of these. For example at 12:00 you have this line: ``` Pizza basicPizza = new TomatoSauce(new Mozzarella(new PlainPizza())); ``` I would intuitively interpret as making Mozzarella from PlainPizza and then making TomatoSauce from Mozzarella. The example below achieves the same results without decomposition and with a lot less boiler plate code, just by changing the mental model to something more intuitive and representative of real life. Are there any advantages to using the Decorator Pattern in situations like this? ``` List toppings = ArrayList(); toppings.add(new Topping("TomatoSauce", 0.35)); toppings.add(new Topping("Mozzarella", 0.5)); ToppedPizza ready = new ToppedPizza(new PlainPizza(), toppings); ``` I'm sure there are cases where Decorators are needed but I often see programmers using certain patterns to fit the solution into the their mental model when they should be reframing their mental model to match real life. What are your thoughts / experiences regarding this?

are you sure you wanna have "Adding dough" in Mozarella class ? (10:00)

You're very welcome :) Im glad you enjoyed it

Bro, trust me, never find such great tutor where I can understand the design pattern so easily. You are the champ dude.

Sorry, but I'm not sure what you are trying to do. Send me a message on youtube, or and email derekbanas@verizon.net

Thank you very much :) I love covering niche topics that others ignore

When I start thinking about using a design pattern I normally first ask if I can accomplish making the code more readable in some other way. If I can't think of another way I use the pattern. You'll find with experience that more often then not you'll use patterns rarely. The positives in knowing them are that you'll start to find other unique ways of solving problems while writing easier to understand code.

You're very welcome :) I'm happy they are helping

That's funny :) Thank you for the compliment. I'm glad you are enjoying them.

You're very welcome :) Yes you could do what you described. It is really my fault because I didn't make an example that required the added flexibility this pattern provides. I tried to come up with a simple example of the pattern and in doing so I didn't get the best example. Sorry about that

Your videos are so great! I always recommend them to my friends taking the Software Design Pattern class at my university. Well done!

Hey Derek, i'm just going to reaffirm what others have been saying on your videos all along: thank you so much for this incredible resource for learning about design patterns. Your videos are of such incredible help while studying, both because of your excellent explanations, as well as the nature of the medium (we can replay a segment we don't understand however many times we want) and the commented code that you provide. I am a big believer of a future for internet with micro-transactions, so i just went and donated you 5 bucks. It is not much, i am a student after all, but the content you provide warrants a gesture from me :)

Hey man, i just gotta tell you that I love your videos and I love you. 3rd year of uni, and you still manage to help me through all the questions I have. Last semester you helped me out with Data Structures now you're helping me out with design patterns. Thank you once again, please keep this up!

Thank you :) I did my best and I'm glad you liked it

Amazing! I'm from Ukraine, but your tutorial in English is easier than any of I could find in native language! Thanks!

Thank you so much for the excellent videos Derek, This is helping me a great deal in prepping for my CS exam! You are my hero!

Thank you :) I'm glad you enjoy them

You can always override the PlainPizza class, add a topping of medium, large, Xtra large, etc. You could have all toppings have the same price and then just override the description. The rule extend what differs between toppings will steer you in the right direction

you're the master; never has anyone or any article or tutorial hit home design patterns to the point in such short and concise manner.

Thank you very much :) It is very nice of you to say that!

Excellent. Thank you so much!!!!! I have read the Gang of Four book, but it is so long that the trees get lost in the forest. Your Decorator is so clear and logical. Bravo!

Very Helpful tutorial, my first project in my Object Oriented Programming course just so happens to be creating a pizza ordering system where toppings are added using a decorator design pattern so this video was exactly what I needed! Thanks so much!

I'm confused by your question. ToppingDecorator provides those methods to the classes that extend it

Thank you :) Im very happy that you enjoyed it

Thanks Derek for explaining decorator design pattern in such simple way... Hats off... cheers!!!

You are a most excellent teacher. I usually have problems learning new (especially programming) concepts, but you made it very easy for me to understand. Your explanation is crystal clear. =)

First of all thank you very much. This is the best design pattern tutorials i have ever seen. We demand some more stuff from you in future :).

That was a brilliant example demonstrating the decorator pattern . Thanks a million!

Yes I slipped up a bit. Thanks for pointing that out

I always first see the running time of ur tutorials before playing. Then I feel like "ohh... so after 13 minutes the "future-me" would have learnt decorator pattern! Cool!!" Its better than counting the pages on a book n thinking "well... need to read 30 more pages to learn decorator pattern.. ahh forget it. will do later" I recently switched organization for almost double the salary (+ better work). And I owe u a big thanks since your videos were a very big help to me.

Sure I will cover the top 23 patterns described by the GOF

Thank you :) I'm very happy that I'm able to help.

Fantastic tutorial, very well presented and easy to understand. Wish more tutorials were as high quality as this one! :)

Man I'm hungry

You have saved my ass. Exam in one week and I was not getting any of this until I discovered your videos. Hero!!!

I am a Senior Developer, I watched these videos from Derek 6 years ago, and yes I am watching them again :) #lifeOfDeveloper

Thanks a lot for providing the code. Sometimes I don't quite get things through verbal explanations, but seeing you implement it and then thoroughly going through the code afterward really helped it click. Also, I think at the end of your tutorials that involve coding, you should do one final overview of what just happened when you run the program. In this video for example, I think you could've taken us through how the objects were being wrapped.

Thank you :) it was fun to cover this topic

You are very kind :) You're very welcome

Headfirst design patterns explains things similarly but using drinks instead of pizza. You did a much better job of explaining it than the book did though.

Derek, You're the best man! The range of topics you have on your channel makes me wonder if there were a team of 4-5 different experts, but its just you, unbelievable. I would love to donate on your site once i have my paycheck. For this video, like others i do have some issues with code or the way it could've been done, but i understand the focus here is understanding the pattern and not the code that is written, Thumbs UP!!, You're awesome!

Thank you :) God bless you as well

8 Years latter and still useful, thanks for the high quality video!

I keep rewatching these series of design patterns in java. So far it helped me make my apps less violent and less complicated. Also, I love pizza! My thanks for your effort Derek. Kind Regards...

You're very welcome :)

This is the best example to get the idea of decorator design pattern. Thanks Derek. :)

The UML association in the diagram is *composition*, not aggregation. Aggregation uses an empty diamond.

man thanks, a year trying to understand this pattern xD it was so easy

Great video! When I think about creating a pizza class with many different kinds of toppings, I might choose the builder pattern instead, so that my code for adding toppings can be linearly written instead of in the form of nested constructors. Are there any advantages of the decorator pattern over the builder pattern here?

I took a short cut. You are correct that I should have defined a Dough class like I did with TomatoSauce. I was just being a bit lazy. Sorry about that

Shouldn't the arrow in mozzarella be pointing the other way around since Mozzarella extends ToppingDecorator? (in the UML) Regardless, kudos on your videos Derek! I'm learning more here than in lecture lol

Awesome. Much better explanation than HeadFirstDesignPatterns. Hats off.

Derek, your tutorials are the best! Highly respected!

Every video from this course helps me to obtain clear understanding of dedicated pattern. Nice work! One remark about Decorator Pattern. You've forgot to implement decorators for meat stuff and olives to obtain perfect pizza :)

Thank you :) I pay no attention to video count, views, or anything else. You guys seem to inform me on that stuff

Why? Why do you have a video about anything I look for? I love you bro.

learning for my software engineering course for university right now and have to learn all of these by heart and these videos are very helpfull thank you

For those who don't know about SOLID principles, I recommend reading up on it. "Clean Architecture" by Robert Martin is a really good resource for this but you can just Wiki it. This design pattern is very powerful in that it directly tries to comply with the S(single responsibility) and O(open/close) of SOLID.

Awsome tutorials, I'm preparing for my exam with your videos!! The examples are excellent

Great! You're very welcome :)

Thank you, but you don't have to do that. I'm not one of the guys that asks people to like and favorite everything. The fact that you find them useful is enough for me :)

Incredibly easy to learn !!!! THANK YOU !

Hey, thanks a lot for these tutorials. They're some of the simplest explanations on design patterns I've come across. :) A question: Using the decorator pattern, is it possible to add / remove decorators to / from the component after it's been instantiated? In this example, is there any way to add / remove toppings from your created pizza, or is this reliant upon been set up at instantiation?

Very nice. All your tutorials are great, thanks!

Hello Derek, First of all you have great videos and i really enjoy to see them. A question, this pattern is only udjusting our existing methods or i can add more methods to the decorator classes ?

Thanks for the video .. They are really helpful .. Rather than reading the GangOfFour book this is much precise and better to be done over a weekend

Absolutely the best I have ever seen in video programming tutorials! You are doing a fantastic job!

Great video on the Decorator pattern Derek! Loved it!

Thanks Derek just having this topic on my OOP Class.. and it helps a lot. Cheers mate.

You should be hired as a tutor at my college. You just saved me 5 hours to say the least, while providing me with information in the most appropriate way. And this is not the first time...

He sounds a little bit like Andy from The Office (Ed Helms)

Thank you so much! Clear explanation, I love you!

It's nearly 1 AM and I'm hungry because of you, thanks

no wories, i just wantes to say something really :-) your lectures are very good

Good Stuff! All the design patterns are well explained. Thanks! :)

That's funny :) I'm glad you liked it

Hi Derek, I've been watching your tutorials since quite some time, they are very well-organized, the concepts are presented in excellent manner - uml-s, wrong-way-to-do examples and so on. Thank you for the sharing I was wondering why ToppingDecorator implements (define the method bodies) the two inherited abstract methods (getDescription getCost) if it (ToppingDecorator) is meant to be an abstract class? I guess, it is meant to be an abstract class in order to prevent instantiation of if (ToppingDecorator), which seems reasonable, to instantiate the concrete decorators. If the two methods are left unimplemented in ToppingDecorator, then they will no be overridden, but directly implemented in the concrete decorators, which will prevent the Open-Closed principle violation. I have an other question. If Pizza is injected in the ToppingDecorator "from out side", doesn't this mean that the relationship between the two is Aggregation, since the life-time of pizza is independent from ToppingDecorator concrete instance. It ,the same Pizza instance, could be injected in another decorator, for example. Thanks

Great Videos! very well explained, great examples, just great, thank you very much!

Hi Derek, thanks for a great overview of the Decorator-pattern! I just wonder, why didnt you put a Constructor in your PlainPizza-class which, accordingly to me, shoudl be reponsible for the the "Adding dough" part? Regards

Given that ToppingDecorator is abstract and implements Pizza, is it stictly necessary to give basic getDescription() and getCost() implementation in that class? Every topping will override that behaviour, so I was just wondering if it is better to omit it or not! Whats your opinion?

Thank you :)