Generics In Java - Full Simple Tutorial

Full tutorial for using Generics in Java!

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Generics in Java can be very confusing for beginner Java learners. Generics are one of the coolest features in Java, but the syntax may not make a lot of sense at first.

In this beginner's Java tutorial video, we'll talk about why generics exist, why they are useful, and all the ways you can use generics in your own Java programs.

Learn or improve your Java by watching it being coded live!

Hi, I'm John! I'm a Lead Java Software Engineer and I've been in the programming industry for more than a decade. I love sharing what I've learned over the years in a way that's understandable for all levels of Java learners.

Let me know what else you'd like to see!

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[Respect_Mah_Authoritah_]

I’ve “known” Generics for many years now but never really understood the difference between usage of wildcard vs a type parameter, even after having read the official docs a gazillion times. But your just one 15-min video has made everything crystal clear. Amazing! Thank You for making the video :)

[thirajsenevirathne]

This is the greatest Java tutorial I have ever found on Youtube. Not too lengthy, covered huge concepts within a few minutes. As well as clear and understandable English.
Thanks.

[shivakumarn.r]

My attention span was 5 to 8 minutes before watching this video, now it's 17 minutes. Thanks Jhon!!

[glenn]

At 16:00 I'm sure others might have had this question pop up in their minds as to why can't we just use private static <T> void printList(List<T> myList) instead of using the wildcard '?'. So although we could use the former format i.e. just with T in this case, but there's a difference between '?' and 'T'. 'T' means that your class or method will use classes of ONLY of type T, whatever T is defined to be, wherever a reference to T is made within the class or method, whereas '?' means that the class can be of ANY type. For deeper understanding of this difference, refer to the Generics chapter of the Java complete reference book wherein there's a specific use-case for when using <T> won't work so one would have to use the wildcard '?'.

[krishnachaitanya]

OMG i never knew i can learn these many things in 17 mins. Man i would love to work under tech leads like you. People like these improve quality of life as well

[clarkvaughan]

Hands down, the best explanation I've ever seen. What a teacher.

[lormalxd]

I just began my Education in Software Developing, one year passed and I've learned so much more from like 5 Videos from John than I've learned in the entire year, that's insane.

[vazzdoin]

This tutorial was so simple that I immediately implemented the generics very easily to one of the projects that I'm working on whereas a day ago I was just refraining from doing it just because of not being very confident with the Generics concept. Great stuff John, this was a very informative yet very simple to understand tutorial. Keep up the excellent work.

[shahdhossam]

I literally love tutors who not only explain the way to write a code but also follow the technique of clearifying why we use this instead of that which is incredibly useful . Thanks a lot ❤❤

[Jesus_Na_Causa]

I'm Brazilian, I learned more in your class with you speaking in English than I normally learn in the classes I attend in Portuguese. Very good teaching. Thank you so much!

[dopoqiu]

Honestly, this video clearly explains what generics is all about. It took me awhile to understand it but right here, it just takes 17mins of your time. Thanks for putting out great and concise content on Java!

[marcossantos-yree]

I know generics for a while. I remember my professor explaining about it and he spent kinda 9 hours, in 3 hours classes to explain what you have done in 15 minutes, unbelievable!!! Shout out to you!!! 👏🏼👏🏼👏🏼👏🏼👏🏼

[arbazadam]

This is by far the best video on generics in the entire universe. Mad respect for this dude 🙏🙏

[Orctupus]

This deserves an award for being the first perfectly clear guide on generics. I've done many courses and many java certified developer courses that fail to explain exactly how they work. Well done.

[Hughsie]

There are just straight up some of the most perfect tutorials for someone like me, even 6 years in the Java industry and now upgrading to newer versions. Thanks John!

[嘉然今天吃战斧牛-uh]

I am a junior Java back end developer, your tutorial is so efficient to explain everything clearly, thanks a lot . Recently, I review your video contents in spare time again and again.

[ganapathi]

This is my first comment in YouTube after many years, video had so much good content and value,
Please Post more videos on generics in real time application, as production ready code that we use for configuring external dependencies

Congrats John, Keep up the Good work ❣️

[ruimenoita]

What I think it's missing is the generics that use the super word, like List<T super Number>, and explain the difference and the use cases of extends and super.

[moeal]

Another well-done tutorial here! Can't wait to see one on java 8 streams as I have not really found one that goes deep into these concepts.

[shareknowledge]

This is the greatest Java tutorial I have ever found on Youtube. Not too lengthy, covered huge concepts within a few minutes. As well as clear and understandable English.
Thanks.😍