you explain things very clearly, and I'm grateful for such a high quality video. Thanks! That said, I have some perplexities with the example you're using (maybe because of my limited understanding; please do not take them as criticisms). 1. In my understanding the strategy pattern is not well-suited to the example. If you have to create a "NoFly" class for the RedDuck, then you're not much better off than the initial suggestion of overring the fly() method in the RedDuck with a "do nothing" method. If the RedDuck cannot fly, in an ideal design one shouldn't tell it how to fly at all. Also, every time I instantiate a RedDuck, I have to remember to pass it the "NoFly" object, but nothing prevents me from passing it another flying strategy. Surely design patterns should "design out" possible bugs, but in this example this doesn't seem to be the case to me. Wikipedia reports, on its "strategy pattern" page, a different example which looks much better to me. It's about a restaurant bill, containing a List of orders and prices, and the "strategy" concerns possible discounts applied to the prices. In this case too there is a "NoDiscounts" strategy, but the situation to me is different. There's only one class, RestauntantBill, and naturally all RestauntantBill instances need to know what discounts should be applied ("no discounts today" is a reasonable strategy); on the other hand the "duck" example mixes the strategy pattern with inheritance, IMHO. 2.If your example the performFly() method takes no arguments and just prints out a string. This is not wrong, but in many example of the Strategy pattern the "Strategy" method actually changed the internal state of Duck class they belong to, ie they are of the type performFly(this). This took me some time to get my head around, and I think a full explanation should also comprehend this more complex situation. 3. I personally don't really like these examples with Ducks, Dogs, Animals and so on. I'd much prefer a realistic (or at least semi-realistic) situation. This is because, with the Ducks example, I have to do an extra abstraction effort to remember what the heck I want to do with these essentially meaningless classes and methods. But this may be just me. In any case thanks again for the video. Regardless of whether my observation has a basis or not, just reflecting on these things helps understanding.

I've made some pretty bonkers class hierarchies because I never thought of doing it this way before. Thanks for the insight!

I really don't understand why nobody gives real world examples

Unfortunally, I didi not finish all the patterns of the book. You were GREAT!!! Your explanations are AWESOME!!!!

You are the best! Please more Design Pattern content.

It would be great to include some real world examples and other content that's extra to the book.

Reading the book and coming here, gave me a better understanding of this pattern. Appreciate your teaching..

Thank you for this crystal clear explanation, please keep going to upload more patterns 👍

Thank you for a simple example! Got my OOP exam coming up and this was really helpful :)

you just made OOP better for me to understand now. I use C# and my instructors could not simply this concept at all. Thank you!

I am studying my software design pattern exam with these videos and this videos are very pure and helpfull than my teacher. Thank you bro, keep going

Thanks for the video. I like using a video game example where you have different types of Adventurers who need interchangeable BattleBehavior strategies.

You're excellent explainer of concepts. Request you to make all 26 design patterns. Thank you

Very crisp and to the point tutorial and wonderfully explained, learned a lot. Thank you.

Hi, thanks for the great toutorial, I just had one question, by including the instance variable in base class is it breaking liskovs substitution principle? Because now every derived class knows about the fly method and it needs a implementation even if it does not know to fly?

Is this not just dependency injection, essentially?

Top-notch explanation. Thanks a lot

awesome video, I just purchased my book a little while ago, I know how to code in all basic functions to strings, booleans to OOP, always was stuck on how to code in the pattern etc.. i think this book will help

Thanks for explaining these pattern.

Nice tutorial, as usual. But I am impressed how nice your handwriting is :) I purchased wacom tablet to try something similar, but boy oh boy is my handwriting unusable :D I have to stick to drawing lines and circles for now..

best explanation

Payment method could be example of it

Amazing

Thanks is great! excited for the next videos and might even get the book to follow along

Thanks, this is really helpful. Please do more videos about design patterns.

Great!!!. Please make a video on facade design pattern

Thanks for the video. Please create more videos for other patterns ...

I was looking for composite design pattern in ur play list .... Can u plz make one ? Btw u r jus super

Can you tell the page no from the book? I'm not able to find strategy patters in Head first design pattern book.

What program are you using the stylus with?

Bro Amazing turorial but you almost left me blind with that IDE

Thank u so much, this the best explanation !!!!

awesome presentation, love it, really learnt a lot, more power!

I'm so glad I abandoned OOP six years ago, and I will never going back to that hell.

Nice video. I have a question, if I need to add one more function like colour of the beak then do I need to pass two objects of two interface while creating mallard duck object. Or how should we proceed with it?

Hi! What do you use to show your whiteboard?

can we use default methods of interface instead of using strategy patter?

Wow, you just happened to publish this video the same day that I was looking for just this. Thanks! Looking forward to the rest

Good job, but are you allowed to reuse a book so closely for your own content? I wouldn't want you to get in to any trouble for this. I understand that it also kind of promotes the book.

Am I right in thinking that Java lambdas would be well suited to this pattern?

when will continue this series enjoy it to the max really

Does Collections.sort(Collection, Comparator) use Strategy pattern?

With java8 , default and staic methods can have body and the same can be reused in multiple classes implementing the interface, the issue with fly() method will not arise and we will bypass the complexity and a chance of multiple inhertance(multiplier parent class), Is there still space for strategy pattern?

I didn't find how RedDuck is implemented in the code. Other than that, it is clearly explained.

Is this a good book if I'm learning js?

rather than using dependency injection, function to set fly behavior in Duck class would be better I guess. Doing that if we have to add another behavior we just have to add another function to set rather than adding dependency everytime when adding a new behavior.

Holy shit I finally understand singletons and dependency injection

This creates dependencies on constructors, so this should maybe be used together with a Builder

In this example why not just assign the "flyWithWings" behavior to all Mallard ducks in the constructor for MallardDuck?

I'm just learning but I think your example is not entirely correct. As you did it, every duck has to fly because you are taking the instance FlyBehavior into the constructor of abstract class Duck. What about ducks that do not fly and do not need FlyBehavior? I think a possible solution would be to create the second constructor of the abstract class Duck without instantiating FlyBehavior.

Ducks fly with wings last time I checked as well😉😂

What program did you use to draw on the screen ??

I don't like the example. How a duck flies isn't separable from the duck. I would do something like say you're building a robot and it could have wheels that roll or legs that walk and they both implement a move interface. Also the joke you missed would be if one of the ducks flew Delta or some other airline.

god, I forgotten how ugly Java was...

"Real life scenario", then the silly duck thing? To me that is not a real life scenario.Real life implies something you might actually use like input or output of data in json, csv, or yaml, or if you wanted to stay academic, calculating grades based various grading schemes. There are probably hundreds of other simple examples. Personally I find examples i can imagine using much more inspiring than abstract caricatures of algorithms.

Cedrick Mccrary the one who structure the strategy to these two components. gang gang

Isn't this just composition?

Is this what Guice did？

​ @evanwest4751 is acts like a massive Baguette

Duck walkerDuck = new walkerDuck(what am i supposed to pass here ); ?

No fly... breaks skateboard

You arrows are backwards and denotes 'has a' instead of 'is a'. Very bad.

So... I dont see why the first example of simply implementing a flyable interface is so terrible.

3 minutes of bla bla bla. Please reduce the introduction

Personally find this book abhorrent.

PHP code example of strategy pattern: github.com/8ivek/design_patterns/blob/main/03%20Behavioural%20design%20patterns/01%20Strategy%20Design%20Pattern/main.php comments are welcome.