4. Decorator Design Pattern Explanation with Java Coding, LLD System Design, System design interview
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- Опубліковано 11 тра 2022
- Hi, in this video we have covered #decoratorPattern out of many design pattern which is asked in Low level system design interview.
➡️ Become a Member: / @conceptandcoding
I always wondered why "is-a" and "has-a" relationship between objects is even worth mentioning, but now I know just how important they are. It's amazing how a small detail like this can completely change the way we approach programming.
Glad to know that
I worked in both product and service industry of small, medium and large size company, i can see the clear understanding and explanation by the narrator on each of the topic and make an analogy to live code in my work. Very well explained in details, that too free of charge ,i recommend these videos to all the freshers or laterals who are working in java for upskilling.
Just can not believe that this piece of gem is free on youtube !!
Really appreciate your efforts. :)
Amazing concept, learning LLD is really an eye-opener. Thanks for this amazing video and explanation.
Thank you, pls do share it with your connections 😊
Nice point : both isA and hasA property is needed! Awesome Explanation!
Unbelievable that we are getting this video for free of cost.... Awesome explanation.
bhai ne kuch videos paid kr di 😁
very good explanation is the best, simplicity is the base here and visual representation is toppings
Wish had explored your channel a bit earlier, awesome content on Low-level design(one-stop solution), Just feedback if you can arrange the videos of the playlist in what order to watch it will be really great for people.
Thank you Yash, not sure if youtube does not show playlist title and description, i have mentioned in both the place that Start from bottom and move Upward, let me check
J is silent in jalapeno😅. Rest video was awesome!!
'Has a' and 'is a' make concept much simpler to understand. Good point you make to explain.
Awesome explanation Sir. Thank you very much
Superb explanation. To recollect decorator pattern, I will remember the pizza example. Thanks a lot of this super useful video.
Welcome
Great job Shrayansh .
The way you explain with examples it makes the concept very clear..Keep it up and thank you very much :)
Glad it helped!
I really appreciate your efforts thankyou so much😇😇😇😇👏👏👏👏👏
Thanks for sorting it in "reverse" order. Glad that you considered the feedback. 😀
👍
Amazing explanation
🤯🤯🤯🤯🤯
Swaad hi agya 😋😋😋😛.
Thanks Shreyansh for this Amazing vedio series. Great content. And Beautifully explained.
Very Well explained sir!
Great work !
Nice video. You can add the main class with example of creation of these objects and using them that would help understand the concept better.
public class PizzaShop {
public static void main(String[] args) {
BasePizza base = new VegDelight();
System.out.println(base.cost());
BasePizza customPizza = new ExtraCheese(new Mushroom(new Farmhouse()));
System.out.println(customPizza.cost());
}
}
Thank you so much for the detailed explanation :)
really thank you sir for your huge efforts, but sir, if we keep a final ingredients price Map in Base Pizza itself, and keep Topping Map containing topping and its frequency, this can be solved much simply for calculating the price, but then again that solution is not scalable ig when toppings list and price need to be updated, thanks again.
I can totally relate Decorator Design Pattern now, yestarday only i ate the 'PIZZA' now i'm learning and watching it. 😃✌
:)
Thanks Shreyansh. Video is very helpful in understanding. I have implemented the same in python. Awesome initiative
Glad to hear that
Great Explanation. Thanks for the video🙏
thank you
Great content. First time i am feeling confident about LLD. Please share your knowledge more with us :)
Thanks there is a complete in depth playlist Manashi:)
@@ConceptandCoding Yes am checking. Thanks again for the content.
Great explanation. But I need to revisit the example once again.
Thank you sir for this Amazing content. I have only one question that for every layer we have to create a new class so if our application will scale too much in that case we might have thousands of layers (Not specifically Pizza problem) so how can we solve that ?
Such awesome content, then its free. i cant explain how satisfied i am satisfied with your content. Thanks a lot bro. i have one request bro, whether you provide content free or paid, it does matter. just keep up. i have seen lots of videos and read books regarding design pattern. nobody explained like you. one thing makes your content unique, you deeply explain OOP concept behind design pattern.
Thanks Saifur
I really understood this design pattern. thank you sir for wonderful explaination
thank you
Very good explanation with code...u did awesome job. really thanks a lot.
Thank you
Awesome, simply awesome
Thank you
Thank you sir for another awesome video.
Thank t
thanks for the video
Thank you sir..today I start calling u sir..Thank you for ur efforts 🙏
Thanks a lot buddy but call me Shrayansh, we both are students,let's keep learning and sharing
this video is a GEM to the whole community, that too by a GEM..... hats off 2 u sir.. all this premium content for free , not possible on this whole planet itself,....
wish the java playlist would also become public / free someday , so that it can reach to every deserving candidate who cant afford the subscription at that point of time... s teachers like you are rare to find, your knowledge is uncomparable...
Thanks buddy
Thanks for this playlist sir. Means a lot to us
Thank you
Amazing video Shrayansh!!
Thanks paji
thoda nhi, bahut useful h bhai, please continue LLD series, you are one of best educators on UA-cam
thank you Prashant. means lot to me.
Thank you so much for the amazing contents
Thank you
Thanks for the great content!
Your videos are easy to understand.
Can we please reorder the videos in the order, currently its in reverse order and we have to play videos manually each time.
Thank you, sure let me check
Great Video , thanks a lot
Glad you liked it!
Hi, Thanks for the great explanation. One small request could you please share the notes and the code that you are using for the explaination in each video. It would be beneficial.
Noted, will do it from now
Awesome😍
Thanks
Great expansion 😃 ....
Thank you
keep going :)
Such a great content!:)
Thank you so much!
Awesome Explantion
Thank you
great!
Very thanks
Please explain when to use decorator pattern and builder design pattern and differemces. Both seems similar.
Can we use interface instead of abstract class..I both in this case both will work fine
Great explanation! :)
Thank you
You should create video where you clearly stat the differences between "HAS- A" and "IS -A" relationship which will help many people
I think in 1 video i did that Vivek, if not then do check the first video of "Live LLD" playlist in that i must have explained it
Here is the timestamp ua-cam.com/video/-UjjfzJ574w/v-deo.html to understand "IS-A" and "HAS-A" relationship
please make a video on is-a and has-a concept with an example. Its very confusing.
Can you show the working demo as well. Need to understand how is main working. Based on input(order is magaretia plus extra cheese etc..)?
Hi great videos. Can you please share the notes or code that you writing ? Moreover, when will the whole LLD playlist be completed?
Eagerly waiting to complete all.
When it will be completed it will be difficult for me to say. I am going with 1 video a week for now. But i am consistent
Another use case for this pattern is the avatar creation system in WhatsApp/FB
Hello sir, first of all thank you for this amazing content ❤.... I hv one question why BasePizza and ToppingDecorator abstract class are abstract classes not interface. ... Just wondering when to use abstract class and when to use interface
Generally both purpose is same to hide the implementation. Interface provide 100% abstraction, while in abstract class you can also implement some methods which are common to child classes
Super clear, I had a doubt: So according to this example "ExtraCheese" is a BasePizza due to indirect inheritance.
So in Vehicle example, the decorator would extend the BaseVehicle. Power Steering would inherit from decorator and in-directly have a "is-a" relationship with BaseVehicle, right
So in a way we are saying power-steering is a BaseVehicle so is it right? As power steering is not a Vehicle rather its a feature
Correct, if you want this pattern and design car with this way. Then you are right
Maza Aagya
respect++
Thanks
Hello Sir, first of all thank you very much for the amazing content!
I have one doubt. For interviews, are all the design patterns necessary ? Becoz it would be difficult to remember all of them 😅.. How much is expected from us if we have 2-3 years experience ?
Thank you. See it's a very valid question, nobody can remember all these designs patterns.
Couple of things:
- How many design patterns is sufficient? Very difficult to answer, what interviewer can ask, we don't know right.
- How to remember all? We don't have to, just try to implement design patterns with your own examples, whatever examples i used take it as a reference and then try to implement with different example. It will help you to remember in which usecase what has to be done.
Keep 5-6 design patterns on your finger tips which is very frequently asked.
@@ConceptandCoding Thanks a lot Sir for the quick and detailed response!!
In my approach, I used an interface for defining a behavior and then created multiple concrete classes implementing this interface, each representing a different behavior. This seems somewhat similar to the Decorator Pattern, where each decorator wraps an object and adds its behavior.
However, I'm struggling to see a significant advantage of the Decorator Pattern over my approach in terms of scalability, flexibility, and maintainability, especially when considering the addition of new behaviors. In both cases, adding a new behavior seems to require just adding a new class without modifying existing ones. Could you help clarify the specific advantages of using the Decorator Pattern over this approach?
You have created A,B C different concrete classes. If you want to create new concrete classes with properties of lets say B , with decorator pattern you will have B1 , B2 etc. But without decorator pattern you might have to write more code to not only include the property of B but also its own new property.
I hope this helps.
Thank You
Thank you
One very important question sir ji, when to interfere and when to use abstract can u make a detailed video in this, i think this will solve many questions of LLD in a thinking way
When you want 100% abstraction go for interface, else go for Abstract class
Yes, i know this, but while in interview when we say that i will create an abstract class or interface or concrete class they always ask why so? Why not interface inplace of abstract class, this is has been asked alot.
So just a request when ever u make any any interface or abstract class please tell us the why interface or abstract please 🙏
Firstly loving your videos! So thanks for that
Q. Is this really good to do something like new ExtraCheeze( new ExtraPanner(new FarmHousePizza())))...
B'coz not Basepizza object in ExtraCheese already contains a topping of ExtraPanner....
While if we were not to use Decorator design pattern... We would have had all the toppings on same level... (May be with a boolean flag)
It might matter if we don't want cheese on top of panner but panner and cheese mixed very well... (Sty could not think of a better example)
Hello sir, thanks for the amazing content. I have one question, in the above implementation instead of creating a decorator class, cant we directly extend BasePizza class for ExtraCheese/Mushroom classes? I think there is something fundamentally wrong in this, but not sure what exactly 😅
just think of combinations of chesse. mushroom and just with base pizza itself.
now if there are 10 types of decorator and multiple base pizza, then no of combinations would be large and you will end up creating lot and lot of classes. thats what decorator pattern saves us.
try to implement what you mentioned and you will get to know
You are awesomeee🔥🔥❤
Thank you
@@ConceptandCoding
Adding English subtitle would be really helpful for larger community.
Yes will work on old video, but all latest videos are in English only
Strategy Pattern & Decorator seems alike to me like IStrategy even BasePizza Can have only HAS-A relation with ToppingDecorator or list (to calculate cost for all types of toppings) right. Please help me to understand the difference , By the way thanks for the videos :) #Concept&&Coding
I think main task of Strategy Pattern is to remove redundant code where as Decorator Pattern is used to solve the problem of maintainability of our classes.
I was thinking, can the Pizza example be considered as a builder pattern as well? Even in this each toppings can be separate methods? Can you clear me on this?
Thanks for the really amazing Videos!!
try it out once. I think it can be done, but need to check.
Hi Sir,
I have 1 question, when both the classes, ExtraCheese and Mushroom have the BasePizza object, then why not add it as part of the ToppingDecorator class itself?
Ack. Will get back to you by eod
By the Dependency Inversion Principle classes should depend on interfaces or abstract classes rather than concrete classes.
What if we directly extend base class inplace of topper decorator
Others : Learning Decorator Pattern from this Video
Meanwhile me -> Learning and Ordering a Margarita Pizza after watching 😂
:)
Wonderfully explained!!
Its more like recurssion, so if imagine there are 100 of layes of decorator, then there might be overlapping subproblems. Can dp be used in that case?
i won't say its a Recursion, to me its looks like more of a hierarchy. Child-> Parent -> Parent ---> likewise
@@ConceptandCoding but a child might not replicate the same behaviouras that of parent.
@@BeyondTheFamiliar_2023 ummm Why not, in inheritance, child has its Parent capabilities+ additionally its own.
har jaga dsa ghusa do matlab
I feel an improvment to this can be rather than creating concrete class for each topping create enum topping list class to dynamically update price for each topping
can you implement and show how for the same example which i took.
@@ConceptandCoding sure
from __future__ import annotations
from abc import ABC, abstractmethod
import enum
import string
from typing import List
class ToppingList(enum.Enum):
extra_cheese = 20.00
jalapeno = 30.00
mushroom = 10.00
chicken_tikka = 60.00
class BasePizza(ABC):
@abstractmethod
def get_ingregents(self) -> List:
pass
@abstractmethod
def cost(self) -> float:
pass
# concrete pizza class
class MargaritaPizza(BasePizza):
ingredients: List = ['Cheese','Bread','Olive Oil']
def get_ingregents(self) -> List:
return self.ingredients
def cost(self) -> float:
return 150.00
class VeggiePizza(BasePizza):
ingredients: List = ['Cheese','Bread','Olive Oil','Veggies']
def get_ingregents(self) -> List:
return self.ingredients
def cost(self) -> float:
return 200.00
class Topping(BasePizza):
_base_pizza: BasePizza = None
def __init__(self,base_pizza: BasePizza, topping:string) -> None:
self._base_pizza = base_pizza
self._topping = topping
def get_ingregents(self) -> List:
base_ingregents = self._base_pizza.get_ingregents()
base_ingregents.append(self._topping)
return base_ingregents
def cost(self) -> float:
return self._base_pizza.cost() + ToppingList[self._topping].value
if __name__ == '__main__':
base_pizza = MargaritaPizza()
margarita_pizza_extra_cheese = Topping(base_pizza,'extra_cheese')
print(margarita_pizza_extra_cheese.get_ingregents())
print(margarita_pizza_extra_cheese.cost())
margarita_pizza_extra_cheese_jalapeno = Topping(margarita_pizza_extra_cheese,'jalapeno')
print(margarita_pizza_extra_cheese_jalapeno.get_ingregents())
print(margarita_pizza_extra_cheese_jalapeno.cost())
@@ConceptandCoding Hey does the below solution follow any anti pattern wrt to decorator design pattern
this code still maintains 'is-a' and 'has-a' relationship. So that is the requirement of decorator pattern .
But here my concern with enum is not decorator pattern but with scalability and managebility lets say i want to add more methodd apart from Cost method like TotalCalories, totalProtein , totalCarbs etc. (lets say 10 -20 methods like this) how easy with enum to support this.
Hi, I understood this clearly, But I have a small doubt regarding Abstract class vs Interface. Can't we use Interface in BasePizza and ToppingDecorator, rather than using Abstract class? Other than this, I understood everything. Super explanation sir.
same question . Can anyone explain same @Concept && Coding - by Shrayansh
Hi. Thanks for the explanation. I have a question. Can't we use a builder pattern to create different toppings on the pizza or add different features to a car? If decorator pattern is a better pattern to do it, can you please explain why? My thought process is that builder pattern is good for making pizza because once a pizza is ordered you don't need to give customer the flexibility to change it after placing the order. Can you please let me know what you think? Thank you once again.
+1 I am even having the same doubt. So, I too feel if some clarity is provided by the author would be helpful.
With my understanding, I feel with this pattern we will not violate Open/Closed Principal because whenever there will be new topping, we can add a separate base class whereas in builder pattern we will be modifying the builder class to add the new toppings.
I also had the same doubt, but in Pizza scenario I think it would be correct to use Decorator pattern since we don't get the all the topping details at the start itself, user may add topping or may not. So this pattern will be used if the object(Pizza) is already created and after that we need to add new features(topppings) basically at run time we are adding new features to existing object. Builder pattern will be used if we have all the details at the start itself while creating Object.
IMO.. You can also have toppings and types of pizza inside pizza.. but decorator pattern is used when you don't want to modify existing object and want to add functionality only.. ex: pizza won't always have toppings..it needs it only for cost computation.. so why have it inside pizza.. classic examples are Java Streams
Apne saraswatya mantra liya hua hai kya bro🥰
Thanks for the videos.
I have a question: why did you use an abstract class? Could we use interface instead?
yes, we can if you dont have a usecase where you have to implement common method , then interface is good too.
Thank you for the prompt response!
Does Response Wrapper that is being used while paasing responses from API also follows decorator pattern?
kind of you can say, but thats a good thinking
can we not use interfaces instead of abstract classes ?
why you used abstract class , can we use interfaces also ?
Could we have used Builder design Pattern to achieve the same?
Can you explain why you used decorator abstract class in between rather than extending base pizza in ExtraCheese and ExtraMushroom classes?
had the same question
ExtraCheese and mushroom can also extend basePizza right?
Why do we have another abstract class in between?
Exactly. I have the same question in my mind.
For the pizza making or adding accessories to car, builder design pattern seems more useful. What’s your say?
could you please try to implement it and see what challenge you are facing.
❤
I could be wrong but, can this problem of multiple object permutations be solved by builder pattern also?
I have the same question. Since the Pizza problem comes more in a object creational use case, wouldn't builder pattern fit more for this use case.
Decorators are used to modify the functionality of an object in runtime. Using decorator for object creation puts the object in an inconsistent state till all the decorators are completed.
In real scenarios, decorator would be useful, when we need to stack up the operations like encoding a file and then compressing etc.
Can we have array if Toppings in Pizza Class and while calc cost in Pizza class add topping's cost also. 🤔
Why are we using ToppingDecorator? If we are anyways inheriting Extracheese then can't we inherit it directly from BasePizza as we aren't doing anything in ToppingDecorator class?
So here inheritance is only used for type matching and composition is used to get the behaviour.
It will give us flexibility in future
Hi,
Suppose we have an abstract pizza class and an abstract toppings class which are inherited by concrete classes . Now, every pizza class has a list of toppings . So, when we calculate the cost, we just iterate over that list and compute the total cost. I have a big doubt that if only has-a relationship is solving this problem. Why do we need such a complex structure of has-a and is-a relationship existing at the same time and what extra advantage does decorator pattern bring into picture ?Looking forward to your reply to this question.
okay, could you please tell me, how you would solve the scenario where you have 1000s of combination like
BasePizze,
BasePizze + cheese ,
BasePizza + mushroom,
Veggie + cheese and go on......
The biggest advantage decorator pattern adds up is control on number of classes if there are so so many combinations possible.
@@ConceptandCoding Thanks for your reply.
Lets suppose Base pizza is extended by two Pizza class Veg and Non Veg Pizza. I have another ExtraAddOn class which is inherited by say cheese, mushroom, paneer and so on ...
Now, I have a " vector extraList; " in Veg and Non Veg Pizza class.
So, whatever combinations of ExtraAddOn you need, you can add to that list and calculate cost.
Only thing is that you cannot mix the base Pizza options, but i don't think that's the requirement here. Am i thinking it wrong ?
I have a question, when we create the base parent class... how we can decide to take interface or abstract. I think both will work fine. So which one to choose in that case, could you please give a little clearity.?
If you want some method to implement in base class which child can reuse, then go for abstract else interface.
@@ConceptandCoding tysm 🙏
Do you have any github repo for notes or doc link ?
So according to my understanding we use decorator pattern for incrementally include or not include features. Can't this be also achieved with builder pattern ??? Can you briefly compare the tradeoffs ( with reply to this comment ), Thank you.
Ack.
Let's say if we have a simple case as a Pizza then instead of abstract class for Base Pizza, can we use interface ?
Yes we can, if you don't want to implement any common method in that
How is a topping "is-A" basePizza? Does that make sense?
Thanks!
thanks a lot buddy for super thanks 🙏
@@ConceptandCodinghello sir , i want to become member so I can access all your videos of this lld series. Please tell me the process
at channel home page you will find the join button, there you can join “Unlock LLD, HLD..” one
@@ConceptandCoding thanks joined
can't we pass ToppingDecorator object in extraCheese or mushroom constructor?