C# Abstract Classes - What They Are, How to Use Them, and Best Practices
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- Опубликовано: 19 июн 2024
- I get asked about abstract classes a lot. What they are, how they work, and why you should know about them. An easy way to think of an abstract class is to say that it fits between a full base class and an interface. Basically, it is a blend of the two. In this video, I am going to demonstrate what an abstract class is, how to use it, and when it makes sense to create an abstract class.
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0:00 - Intro
0:58 - Demo application walk-through
3:19 - Creating a base Class
5:53 - Making the base class abstract
8:44 - "Interface portion" in the abstract class. The blend of interface and base class
12:56 - Class inheritance in an abstract class
16:00 - When to use an abstract class
For clarity, this chap's tutorials are second to none. He takes a dry subject like 'abstract' classes, breaks it down, gives easy to follow examples and seems to enjoy conveying information to those less experienced than himself. Tim Corey deserves a cyber standing ovation.
Just to clarify: I have no idea what a 'cyber standing ovation' is as I simply made it up on the spot. An image of grateful theater goers doesn't lend itself to internet usage, true, but I'm sure you get my drift.
I appreciate the kind words and the ovation.
Hi Tim, I've been a lead for the past 12 years for 2 to 80 devs teams with tons of junior and mid level developers and I've never been able to explain in an easy and understandable way abstract classes, you nailed it my friend, from now on everytime a dev ask me to explain abstract classes to them I will send them a link to this video and demand from them to donate 5 bucks to your Patreon ;) Thank you man
I am glad it was so clear and thanks for the recommendations.
Also for those that might be curious about the difference between a virtual method and an abstract method:
Virtual methods have an implementation and provide the derived classes with **the option** of overriding it.
while Abstract methods **do not** provide an implementation and **force** the derived classes to override the method.
Thanks for sharing.
Oh my God !! 8 years after school, I for the first time, understand what is an abstract class. And the differences with an interface !
Thank you very much Monsieur Tim Corey
I am glad it finally clicked.
A short video that absolutely nails it!
"A truck is not a car."
True... but a truck is a vehicle, and so is a car. So your base class would be vehicle and car and truck would be child classes since they have similar properties. A motorcycle is also a vehicle, as is a tractor. And all of them implement similar properties.
Thanks!
Thank you for always explaining things in a calm and structured way!
You are welcome.
You're honestly the best Tim!! Your videos have helped me grasp the foundational topics so much, and I just love the way you explain concepts in such a clear and concise manner. Thanks loads!!!
Thank you!
Thanks for this, I have been reading a book that is heavy on the how and light on the why/when. Your concise explanation helped me to understand the use cases for abstract classes better.
Excellent!
Thank you, Tim. If you find that I thank you more than once for the same video, it's because sometimes I watch the same video a lot of times :) (I wish I could learn only by watching the video once)
You are welcome. I am glad they are helpful and I am glad you are using them as reference material. That is how I intend for them to be used - they are visual archives of how to do things in C#. Even I refer to them sometimes.
Before this video I thought I understood what an abstract class is and how it works. Now I can certainly say I know way better than I used to. Thank you Tim! Awesome video!
Glad it was helpful!
Thank you for making this video. It absolutely helped me remove the fog in my mind and made it easy for me to explain Abstract Classes to my son.
Excellent!
This level of knowledge needs to be made illegal, Wow!! such clarity and finesse!
Thank you so much @IAmTimCorey
I’m glad it was helpful.
Wow you picked a great example to explain this. Also the explanations themselves are super understandable. In just 20 minutes you explained this way better than my teachers did in multiple lessons. It helped me a lot, thank you!!
I am glad it was so clear and helpful.
I have taken many classes, and I can certainly say that you are very good at teaching. It is a pleasure to learn. I will certainly be purchasing classes.
I appreciate the kind words.
I laughed out loud when auto generated subtitles said "a toilet on Tundra is not a car" at 17:52
great explanation btw, I think I understand all now
I work hard on the pronunciation, but once in a while...
Man, this is really great. I swear I have had so much trouble figuring out abstracts, delegates, and interfaces but these 3 videos changed that. I will be purchasing the full versions of your lessons and learning c# here from now on. I like to re write the code on my own to make sure I understand what each line is doing, and then trying to create my own examples after it helps it stick.
Awesome! I'm glad they were so helpful.
I finally understood the use of abstract class !! Thanks for your great video
Awesome!
thanks Tim for giving amazing hands-on insights.
You are welcome.
thank you again for a simple explanation of something that seems complex
You are welcome.
This video was sufficient enough in the explanation in the sense that I can have that "Oh yeah," moment while working. Thing is you have so many options to do the same thing and everyone will tell you something different on how to implement a solution. Sometimes you just need to be aware of a useful functionality.
Thanks for trusting Tim and watching
Once you start talking i get this weird awesome vibe that keeps the whole thing intersting to me. You are a wonderful tutor sir, and we are very grateful for what you're doing!
I'm glad I keep your attention.
Very clearly explained, it was fuzzy in my mind before but now I understand what and why you might use abstract items. Thanks!
Glad it was helpful and clear!
WOW! clear and concise the best explanation I have found of abstract classes
Thank you!
Really good explanation for basic approaches. Good to have you here!
Thank you!
Clear explanation and presentation on abstract classes. I like the way you bring the practical side more into your videos rather than presenting only theoretical aspects.
Thank you!
Thank you alot, I will never forget this.
You are welcome.
This could represent for me the BIG ANSWER I was looking for!
Thanks a lot, Tim! :)
You are welcome.
Writing my 70-483 c# exam soon and your videos definitely helps me prepare much better!
Great!
I don't know if you still read your comment but man you're a amazing. Thank you very much. Teaching the basic, base, interface cleared up a lot of stuff for abstract classes.
You're very welcome!
This video helps to get a quick recap on almost benefits of abstract classes.. Great!
Excellent!
Excellent & clear as usual, thanks Tim!
You are welcome.
Best explanation. Understood finally! Thanks a lot.
You are welcome!
Great explanations as usual! Thank you Tim!
You are welcome.
Thanks, I know of the use of words "virtual", "abstract" in C#, but it just started to get messy in my head on what's the actual difference between interface and abstract. Now it's clean for me again!
I am glad it was helpful.
Thanks for your videos! They have been helping me a lot!
Great!
Excellent insightful video tutorial, thanks!
Great!
Best explanation by miles, thanks Tim!
Thanks!
Your videos are the best, Thanks for all the great content!
You are welcome.
Great Tim. Very clear explanation
Glad it was helpful!
Fantastic explanation, thanks so much!
You are welcome.
Very clear explanation, thank you.
You are welcome.
Great explanation. Thanks a lot Tim.
You are welcome.
Thank you so much for your video! Your videos are really helpful!
You are most welcome. Thanks for watching.
Tim, Bob Tabor and Kudvenkat are my teaching guru
Thank you!
very clear explanation,tanks!
You are welcome!
You explained it well, thanks for your educative video
Thanks for investing your time with Tim.
Wow. Thank you very much!
You are welcome.
really amazing job. thanks.
You are welcome.
This is really good explanation. Whole video is good, later part i liked most. Right we should not use concept because it is there but should be very careful on where it fits perfect specially in case with inheritance as it must maintain Is-a relationship. Thanks Tim!
Excellent
Thank you Tim you make me understand the benefit and different between abstract and interface and virtual modifier, I studied java but not understand.
Glad it was helpful!
Good Video, Covers Everything i want to know about abstract class
Thank you!
very clear, thanks!
You're welcome!
Great video, very clear explanation, thanks Tim.
You are welcome.
@@IAmTimCorey Tim, one question if I may from your videos I understand that interfaces can have properties and methods (WITHOUT code in them), and abstract classes can have abstract and virtual methods (WITH or WITHOUT code in them), but not properties. Is that correct? Is that another way to differentiate when to use an abstract class and when to use an interface?
Thanks.
You can have properties in an abstract class.
great tutorial. thank u so much
You are welcome.
A really good video.... Thank you so much for this...
You are welcome.
🥺😪Thank you so much, this helpled me complete my assignment and i got a distinction 🎊
Awesome! Congratulations.
Yet another awesome one!
Thanks!
Perfect Explanation!
Thanks for watching and sharing your thoughts.
Clear explanation , thanks ton
You are welcome.
Thank you for your time and effort, this really helps me getting better, I just have a hard time understanding all the different classes and how to use them all together with interfaces, its a hard topic to be honest (or I am just a slow learner that is possible aswell)
It is a hard topic. It helps if you start using them (even if you don't fully understand them) in demo projects. As you see how they work, you will get a better grasp on them.
@@IAmTimCorey True that, I try to work with them everyday now making small demo's just for fun, it does help me understanding them all better, and I come watch a lot of your tutorials they are really helpful. At this moment I am following a course for C# and we just started with classes and interfaces (& generics). Everyday its going better, its awesome to see myself improve. Thanks again and have a nice day
Great Explanation!
Thanks for watching
Very clear explenation thank you
You are welcome.
love this! I'm studying for my promotion exams to become a mid level software engineer. i am feeling confident!
Great!
Great job with the video, you got me out of a serious headache!
Glad I could help.
@@IAmTimCorey Your videos are great! Helped me a lot starting my job as a junior!
Good job mate, thanks!!
You are welcome.
You are the best!
Thanks much.
Thanks!
Bravo Tim!Sei molto bravo!
Thank you.
Hi Tim. Thanks for your great vid as always. Can you do a mini course on Data structures and algos with C#. That will be great!
Thanks for the suggestion. Please add it to the list on the suggestion site so others can vote on it as well: suggestions.iamtimcorey.com/
Awesome video... Thanks!
Thanks for growing your skills with Tim
Another great one!
Thanks again!
Interfaces and and abstract classes got even more similar in C# 8 since you can now define default implementations of interface members.
Yep, there are definitely more similarities, but their purposes have not changed. Don't use an interface in place of an abstract class just because it can have default implementations. That will cause you nothing but pain. Default implementations cannot be used on concrete classes, just with variables that use the interface. Also, they aren't designed to act like abstract classes. They are designed to allow us to upgrade interfaces without breaking legacy code.
Thanks a lot Corey..
You are most welcome. Thanks for watching.
This "IS A" fabulous video. 😃
Thank you!
Thank you so much!
You're welcome!
Thank you so much for taking your time and making all these videos. Appreciate your efforts !!!
I would like to know if you are planning to make a video on Reflection ?
It is on the list. I've been avoiding it a bit because it is such an abused topic (reflection is rarely the correct answer) but I'll cover it at some point.
Glad to hear that, I'm interested too
Very helpful, thank you
Great!
Very informative..thank you so much..
You are welcome.
Okay this is some super impressive stuff
Thank you!
really great explanations
Glad it was helpful!
Thank you that is great
You are welcome.
that was so perfect oh my god you're like the god of I can teach everything to anyone... amen
lol, I am glad you enjoyed it.
Hi Tim, please teach us about Aggregation, Composition and association. Great videos btw.
I'll add those suggestions to the list. Thanks.
Great video, Thanks Tim. but what is ur opinion on using the interface IDataAccess for the DataAccess class and then use the DataAccess class as an abstract class ?
Great explanation Mr. Tim, thanks, could you cover please the best practices to make commercial applications
I am going to cover this in an upcoming series.
awesome explanation
Great!
I like it. Thanks a lot.
You are welcome.
Really helpful and awesome for beginners not to struggle, like some of us, later down the road😊! Do you have any “best practices” for designing the sql(or any relational) data structuring? Keep on rocking, C# for life!
I have a course that covers the best practices for designing a SQL database: www.iamtimcorey.com/p/sql-databases-from-start-to-finish
Thank you!
You're welcome!
Good video. Sometimes I find it challenging to figure out when to choose "composition over inheritance". You mention interfaces here, and also how not to treat a car as if it were a truck. Perhaps a future video delving into how/when to choose composition over inheritance. For example, instead of having a car and truck inherit from an abstract vehicle class, just have them both implement the IDriveable interface? ... it's probably one of those situations where there's no right/wrong way, so a video looking at the tradeoffs of doing composition vs inheritance might help. BTW, as I write this I see the Composition Over Inheritance wikipedia page has been flagged as "confusing" since 2015.
Thanks for the suggestion. In general, I default to composition because inheritance is really such a small target. However, it does depend on the situation. I agree that it can be very confusing. I'll add the suggestion to my list.
This is such a basic topic, but also a typical interview question!
Yep.
Thanks Tim
You are welcome.
This a great way to showcases the usage of an abstract class, thanks, Tim!
I've worked in different companies and we were using C# as one of the development languages, but I didn't see any usage of an abstract class.
My question is: Is it necessary to use abstract classes to achieve the best practice?
It depends on the situation.
Thanks, well exmplained.
Q. For the same example, if you follow SOLID, will you implement IDataAccess interface to DataAccess abstract class?
Good guy Corey thanks! :)
You are welcome.
Hi Tim, is there any way to create an abstract class and use it for user control classes? I have a bunch of user controls that contain lots of the same properties and methods. I have to copy and paste those and debugging them is a nightmare.
thank you!
You are welcome.
Great presentation as usual. But this video would feel a bit "in there" for someone new to OOP in general. I think a longer video on architecting software, where requirements are discussed first before a design is created, will remove any cobwebs surrounding the use of Base classes vs Abstract classes vs Interfaces. Given your teaching style, it would become a definitive video on this subject on RUclips.
That's what I do with my start to finish courses. I try to show you these things in the real world.
thank you
You are welcome.
amazing video
Thanks for watching
Great Video Tim !! How do we decide when to use Abstract class and when to use an interface? Also can we achieve Dependency Inversion through Abstract Class?
Good question. In order to use an abstract class, you need to have an "is a" relationship. So a cat is an animal, so CatModel could inherit from AnimalModel (possibly). Inheritance is a lot harder to use than people think. Remember that you can only inherit from one parent so while the promise of code sharing is great, you can't just use it as a mechanism to not write duplicate code. You need to be very careful about that relationship. When it is done right, though, inheritance (which is what Abstract classes are) can be powerful. For most scenarios, though, Interfaces are the better option. You can have multiple, they can be specific to your needs (look at the Interface Segregation Principle), and they don't imply a relationship. Dependency Inversion really doesn't do well with Abstract classes because you are still somewhat dependent on that abstract class. It is better accomplished with Interfaces.
Thanks for clarifying Tim!!