Programming: When EXACTLY to use an Abstract Class? Java & Kotlin Interfaces vs Abstract Classes

A viewer asked a question about why I preferred to use an Abstract Class over an Interface in an older video on the Open/Closed Principle, and I thought I would use this opportunity to explain exactly why I think yuo should use an Abstract Class over an Interface. Although the original video was about a Java example, you can apply this same principle to Kotlin. Just be aware that Kotlin also has Extension Functions, which are often a great substitute for Abstract Classes!

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[deshpasheeto]

This is what exactly I was looking for. Thanks a lot Ryan...! 😊

[alokporwal]

Weeks after searching a resource for knowing the reasonable difference - I finally found it!! Thanks a lot Ryan!!!!

[chriscampbell]

Really appreciate the explanation. Most tutorials gloss over why these items are needed.

[thelumiereguy]

A junior Dev here
Had this question in my mind for a while now
I look it up and what do you know... my favourite youtuber has a video on it
Thanks man!

[ManishKumar-bbql]

Exactly what i was searching for last 5 months... it was there always... few words of yours connected them together and now i have +ve vibes for Interfaces and AC.

[diontan]

thank you very much for the explanation. I just got a question from interviewer regarding to this. I blew it because i was always confused when it's a good choice

[rifqiarfani]

wow ... finally a crystal clear explanation .. thanks man

[LukeChavers]

First, thank you for making videos, you seem like an awesome dude. IMHO: ditch the white-board and speak while you code. I appreciate it either way.

[ShubhamSinghMusic]

This was exactly what I was looking for! Glad I came to this video.. saved me a lot of effort.
Thanks a lot bud :) Great explanation!

[baoton]

Exactly what i was looking for. Thank you very much.

[ddthemaste]

Whenever I wanna sleep, I come here to listen this guy.

[symbolykos]

Thank you for this explanation! It was very good.

[osehiaseehilen]

Thank you so much; I see the difference between behaviour and implementation.

[pythonxz]

Interfaces share definitions, abstract classes can share definitions and implementation. Interfaces are better for polymorphism (implementing multiple interfaces), unless you want default implementation.

[Aspiret]

Dude this was so well explained. Thanks!

[shonubijoye]

Really loved the explanation. Thanks a lot Ryan

[eliassherlocky]

i thought this guy is Ed . Snowden *.*