8.22 Interface in Java 8 Default , Static Methods | New features

[@fernandomora1963]

I watched two hours of Navin's tutorials and I'm just trying to get a refresher on Java. I'm so upset that he wasn't around the years when i was learning Java. If you are starting to learn Java and come across Navin's playlist... it's like you've discovered a gold mine. Now i'm basically watching the rest of his tutorials because he's so clear and fun to watch.

[@bhavik.kothari]

I totally agree

[@nithyashreenaidu8357]

yeah he is diamond

[@sanketdhamala8456]

@@bhavik.kothari Totally agreed. Alot of videos on programming are either extremely boring to listen to or they're not as concise. Thank you Navin

[@universalstarcreations7297]

But these videos are of older versions of Java. Many advancements took place in these days. If those advancements are too covered it'll be more helpful for the fresher's now

[@jesseduncan1140]

I dont mean to be off topic but does someone know of a tool to get back into an instagram account? I somehow forgot my login password. I would appreciate any tips you can offer me.

[@AmitKumaarrr]

The way you have explained I have never seen such an easy tutorial about basics of Lambda express in Java.

[@premkumareaswaran6875]

Thanks for this amazing tutorial Navin. You are saviour. Just would to add something. If there are two interfaces which define the same method (Ex: show()), then the class that implements these two interfaces does not always have to define the same method. Instead, it can use the "super" keyword like below which will also work. .super.show(); Nonetheless, thanks a lot once again. You are an amazing teacher.

[@saurav0203srivastav]

Hi Prem, actually in this case you have to define the show() method in your class and then you can choose to call show() method in your definition by using InterfaceName.super.show();

[@adriano.santana]

Been trying to learn Java through books, udemy courses, articles, and so far you're the best teacher I've found. Thanks,really. I've been stuck with some subjects like interfaces and your videos are clearing my doubts.

[@JayPatel12928]

This is a gold quality information, take a bow Navin! I know this because I have been here for a while now and having worked with Java for 5ish years, I have rarely found such good quality videos. Pure Gold!

[@psawyer871]

Indeed!

[@MetaBlueAvatar]

This is the most comprehensive video I have ever seen on default and static keywords. So many details listed out with such a simple and evenly paced delivery! You, sir, are simply amazing!

[@subashchokkalingam6312]

I was watching your videos past 3 days. i was really immpressed and appreciate your efforts to explaining the difficult concept iin the simple way. I was quit out of IT industry (exp 14 years) around 4 years back and starting doing business in the different verticle (Non-IT) but after seeing your videos got an interest to work again in IT and come back to work in Java with latest technologies.Since you are there for me to give technologies in the simplest way. I recalled all my 14 years of experience in 2 days. Really appreciate for your effort on this. Salute to Naveen. Thanks Subash C

[@himanshidhamija9524]

I am watching this years later and still so relevant,its such a great quality content. I have not found anyone explaining java and making is to easy to understand and learn.Thank you for your hard work sir. Its really helpful

[@prashantshekharrathore4661]

Sir I cant stop watching your videos....I open laptop to learn some DSA and end up watching your videos one by one. Damn Naveen sir your are awesome. God bless you. :D

[@sebastiancapone3284]

I have looked at several tutorials ... I consider myself a perfectionist and I like to learn, not only to know a programming language from above without going into the details. By your way of explaining I can see the passion you give to your videos and when I look at them, I have the security of learning, because you go to the smallest detail. You are very perfectionist and this is really appreciated ... There is no other course, which has caught me like this ... I really appreciate it.

[@sneha_d_mystery_princess]

Navin sir... I must say... ur explanation is too good... u make things easy... by taking the exact appropriate cases... Thank you so much...

[@nagapradeepvankayala7301]

Navin is Awesome, no matter how long the video size is, my same interest levels would continue throughout the video from starting till ending, excellent explanation skills he has...Yes, Navin is a Gold mine, Diamond, and even more than that. We are all so lucky to have him. Love you brother :), I wish God bless you with lots of energy, skills, and continued enthusiasm towards sharing knowledge like this

[@rasul_dude]

Your tutorial is not so long and also not so short. Your tutorial are really perfect

[@jitheshss90]

Perfect tutorial. If anybody has to know about the Default Method in java 8. Please go through this video and I recommend this.

[@watchb4udie398]

it was nice listening so for and thank you for putting your effort in teaching us.

[@priyadarshiniMG]

Very well explained the concepts and difference between the interface and abstract class with perfect example and explanation in an easy way. Thq so much dear👍👏🤗

[@swaminaidu9454]

You are the reason behind my earning in software field.thanks a ton.keep doing videos for geeks like me.Waiting for more videos

[@shivaramkrishnadurgi4253]

Amazing teaching Naveen reddy...so crystal clear...

[@elamurugup352]

Thanks for this session Naveen. Jsut want to be more clear,Could you exactly differentiate the difference between abstract class and interface since both are defining methods in java 8?

[@6977202865]

your making everything dead easy to be understood with your explanations!!! you are amazing!! thank you very very much!!!!

[@jaserq]

He is the best with his style.! And his signature is "HI ALIENS" :)

[@prameelabanda1568]

HI Navin, I kept watching and learning through your tutorials. Your way of teaching is good. My only suggestion is , please use real world example for every concepts which helps to understand quick and remember the concepts for long go :)

[@manikandand2541]

yes sir please suggest this question

[@neelamsen3896]

Yes my concern is also that.

[@ankitsaxenamusic]

You're amazing.. Hats off to you Naveen. No book can describe with such an ease. Kudos.. Keep on posting more videos :)

[@tranhai5146]

Your Java 8 - Interface lession is perfect.

[@sumanjogi614]

It feels so good to learn from you!! I have no words to explain it. Others will understand for sure!!!

[@truptigandhi891]

U made this concept so easy.....👍👍

[@erikmueller5622]

An interface is a way of grouping classes. The reason for this is that any class that implements that interface must "do" all the methods that are written in that interface. So if there is an interface called "animal" which has methods: eat, sleep, walk, run, jump, then we have a bunch of classes for different types of animals, we would "group" all the different animal classes together by making them all implement the interface which means they must all "do" the methods in the interface, because those methods are common to them all. If that sounds exactly like inheritance with an abstract parent class that's because it is. The reason that an interfaces are used instead of regular abstract class inheritance is because in Java a class can only have one parent class but can many interfaces interfaces. If a class could have multiple parent classes then there would be no point in interfaces.

[@vivekmerugu6711]

Your are explaining the concepts very beautifully and with ease. The way you explained the concepts with real time examples are really awesome.

[@parth191079]

Hi Navin, I became your fan and a "chela" after this video! Awesome work, sir! Thanks a lot!!

[@sureshsharma1808]

Yes. same here. He doesn't create complexity and very centric to make other understand. Great Job Sir.

[@SirThanksalot_1]

did somebody say 'Thanksalot'?

[@chaturadedigamuwa969]

Navin is the best guy to learn java. Thank you so much

[@gunavanthamgowda669]

Hi Sir, I love the way you explain, at last you told we can access static method of the interface n main like (I.show()) method without creating object of interface I. But is it mandatory to implement the interface? could you please elaborate static methods.

[@rajendralella6956]

Very well explained with examples, simply brilliant

[@Harsh_r_mh09]

Great level of teaching!

[@sumitsouravamohanty8935]

At 14:35 can you please tell me how you know this "Third Rule " in java 8 .. Have you google it or explore it on your own..

[@Spider-Man_67]

Thank a lot sir for explaining it in a pretty simple way.

[@balramkewat9576]

11:14if we implement both interface in one class .. 11:15 define the show(); in Class C, then which method should call?? class C method, or interface I's method or interface J's method

[@himanshushekhar8551]

u r such a amazing teacher sir..you have clear my all concept..thank you sir..

[@ajaydhiman2368]

want to add 1 point here, If class C implements both the Interface I & J then its not necessary for class C to give the definition of static method (provided you are not calling it in your class C) but its necessary to for class C to give the definition of default methods (even though your are not calling it in your class C)

[@deepanshubabbar9324]

Thanks a lot naveen reddy for these tutorials. You are one of my favourites when it comes to programming tutorials. The tutorials are perfect.

[@alpesh003]

🙏 This is awesome! Please dont stop. Hope it benefits you a lot.

[@khadarzone]

Good one Navin... Very helpful in understanding java 8 concepts..

[@rohn3711]

14:07 what if we remove 'public' from class A 's show() method and tried implementing 'I' and extending 'A' ? Is this priority given on the basis of methods access modifiers ? or on the basis of class or interface?

[@hetalrachh5665]

Really useful content !! Thanks for your videos.

[@vijaykumarreddyt3287]

Navin Reddy, You teach Great

[@deeps2111]

Very well explained. Thanks Navin

[@meena7222]

The mention of function declarations in C was helpful.

[@sindhusudhakaran1731]

Thank you so much Navin for this video .. it's very helpful

[@AnshumanSharmadev]

Wow! Amazing! Loved it! Thank you!

[@HarishV-q1i]

i have doubt about 12:00 bcoz you created two interfaces and one class. and then you wrote a show method and you said we must define show method also in C class, then we ran program and which show is called from class to interface I or J?

[@shashgo]

Navin, So I understand that up until 1.7, we can do multiple inheritance with interfaces because interfaces dont implement methods. And Im assuming that the answer to why we cannot inherit from mutiple classes, even if the classes are abstract is that these abstract classes CAN all implement the same methods. Coming to Java 1.8, what is the benefit of making it possible to implement methods in interfaces? If we can inherit from multiple interfaces that all implement the same methods, and then have to implement the method again in the child class, then what is the benefit. We have to implement the same method thrice. Also this is like inheriting from multiple classes, so what is the reason for this new interface definition?

[@bhavyakumarpanchotiya8254]

Good Video sir and thanks for provide some information related to java 8

[@themodestai9603]

Best teacher ever!

[@007ayansinha]

I just love the way he starts with the word “welcome back aliens” 🤓

[@naveenkondamuri4946]

Thank you so much Navin for the wonderful explanation. If possible, please provide sessions on Spring Batch, and Microservices.

[@kalyankumargudla6027]

Thanks you for you videos . Have question When our class ‘C’ implement ‘I’ and ‘J’ as you said we should override the common method to avoid errors . When we use third party libraries , if our class implement two interfaces if both having same method in there interfaces as per tutorial we should override common method , but here we don’t know the business logic of interfaces common method . Could you pls explain this

[@sreelekhapola8813]

In this you explained like when we have two interface with same method , in that case we have to override that method in the class. after that i didn't understood are we calling the implement methods or what we are doing after overriding

[@aashishkumarchauhan8057]

Hi Navin, Thanks for explaining in such a good way. I have one doubt about both abstract class and interface can have methods with implementation in Java 8. Then what is difference between both ? Where should we use abstract class and where we can go with interfaces ?

[@justforjava192]

You obviously can define methods in an interface, but it isn't *designed* for that. Do it if you have no other choice, (just like List did it for backward compatibility). Interfaces are designed for 100% abstraction. They, moreover don't tell what your class *is, but rather, what it can do (which is why we name them with an adjective rather than a noun).* Realize an interface doesn't affect its implementor much. You could easily retrofit your class to implement or unimpliment an interface, without changing the existing implementation (even if it's already a subclass, due to multiple inheritance). This is impossible with an abstract class, as their subclasses hugely rely on them. Hence, when you have to implement methods, and your subclasses rely on their parent's implementation, choose an abstract class. Else if you wanna just define the behavior of a class, choose an interface.

[@prashantaarya3852]

No doubt video is helpful but not complete. For that we can use show(){A.super.show(); B.super.show();} whichever implementation you can call.

[@divyad9144]

When we doesn't know any implementation at all, we only have requirement specification then in such cases we go for interface. And when we know implementation but not completely (partial implementation) then we go for abstract class

[@sasmitamoharana39]

Hi Navin, Thank you and nicely you explained, I have one doubt, what is the difference between abstract class and interface in Java 1.8?

[@logic_master950]

Interface only built with abstract methods(pure virtual functions). No defined method allowed in interface.

[@logic_master950]

Interface only can have abstract method

[@DR-pi9vk]

@@logic_master950 But that s not true anymore since 1.8. That s what he explained in this video. I still dont see a difference now between those two classes

[@logic_master950]

@@DR-pi9vk thanks a lot , dear

[@NarendraKumarAchari]

Thanks a lot Naveen for your effort to create all these Video - Hats off

[@SharadMeghnathi]

I have one doubt in last few mins. You said at 15:50, that if we define method inside interface and the same method is override in the implementing class it won't work. I think you are wrong here. It will call local method and won't generate error. Correct me if I didn't understand of taken it wrong.

[@charanteja4619]

he mentioned it will take from class method rather than interface

[@iccherherbarium9688]

Then what is the profit of defining show in interface I and J ? Referring to third rule example 14:20

[@vijayakumarvj]

excellent video, pretty clear.. I don't know why 28 dislikes

[@MahendraBabuRajendran]

All C++ concepts are coming back in Java! Those who worked with C++ will find this easy! :)

[@princevijaypratap6025]

sir u have explained very well that why we should have a default method in java 1.8 interface but please can u elaborate the significance of having the static method in interface too with any real time scenario or example like u have explained for default one because I don't see any practical requirement of doing that.

[@rohitspeaksout]

interfaces have been turned into abstract classes essentially. C++ never had interfaces and allowed for multiple inheritance with methods of conflict resolution in diamond problems. I think Java can get rid of interfaces altogether may be via small steps such as Java 8 to remain backward compatible. Great tutorial though :)

[@dexterdenmark5988]

I like this lecture Very much! Thank you !

[@karthikeyat9386]

I think you have deviated from the actual point. At around 3:00 you were saying that defaults methods are introduced so that we can use the new features like Stream API, etc.. But you deviated from that point and talked on rules of default methods. Can you please bring clarity on how Java developers benefit in using default methods to use new features of Java8 thank you.

[@amitghosh6199]

can you explain the purpose of Abstract class in java8 when we have interface with default method. would appreciate if you comment or create a video on this. Thanks for providing awesome learning experience for all of us.

[@scars707]

and why do we need to implement and make our own method in the class c ?

[@chungwm]

The word hidden by [Telusko] at 14:20 is "ThirdRules"

[@shivpatel8288]

We are not "DEAF" buddy.

[@bodduanilkumar7783]

Hi Navin sir, Example u explained using third rule is always calling first interface rather than the class which is extended

[@rtheame4704]

Really explained well. Thank You. Can we use super keyword to solve default methods diamond problem

[@arpitanand6534]

You rock Navin, I am your fan

[@neerajmahapatra5239]

You r freaking amazing man😝😝

[@VishalRaoOnYouTube]

11:51 I think that even when you have the diamond problem, you can still invoke the interface's default method from the class definition by calling either I.super.show() or J.super.show() Let me know if that sounds correct. stackoverflow.com/questions/19976487/explicitly-calling-a-default-method-in-java

[@FaycalAZIB]

I've explain this point in my course

[@prithvik8448]

Exactly that's what am thinking 🤔

[@AddisEngine]

Great explanation !

[@foxhound4829]

Very cool explanation with some very good examples. Keep it up!

[@varunsharma264]

Sir! Your Tutorials are really helpful. Thanks

[@FaycalAZIB]

check my course about java 8 :)

[@_Nikhil_Bagde_]

Nice work. Clear and useful videos

[@rubanprakash8088]

Hi Naveen you are just awesome... god bless you and keep uploading videos it really helps me. thanks a lot.

[@pradnyapotdar7768]

Hi Navin. Thanks for info. But can we add static main method in interface. If yes then how to execute it ?

[@rajkapoor944]

really good man - highly rate your great explanation. Thanks

[@AmbujRajput]

One of the best video of your channel. Thanks :)

[@priyagawai6963]

Thank you sir, it's really helpful. Very well explained.

[@craftyrouze]

Thank you for a very good explanation. I have been using default methods a lot, but never occured to me there are limitations

[@edgarasstasiukaitis3062]

From first look, main difference between interface and abstract class now is only that abstract methods have bigger priority...So why do we need interfaces any more?

[@esakkirajn4531]

Is we can define interface static methods only inside main method or we can define any methods.?

[@bksolvent1]

Good work Mr Naveen Sir

[@half-blood-prince]

Your way of explaining things, and sentence construction is great bro. keep up the good work.

[@warneyfied]

Great tutorial. Thank you so much!

[@anirudhgahlot6361]

Excellent session, cleared many concepts.

[@lifechanger2650]

Best explanation. I want to ask as you have said that the default methods has low priority than the normal methods. So what about static methods?

[@Avinash8643]

Why class has more power over interface when they are implemented / extented by the same class ?

[@adarshverma3372]

because interface basically represents a role-based inheritance where as the class represents the feature-based inheritance that's why we extends first the feature and then uses someone's other role or define particular role(interface).

[@sunnyshah2262]

Your style of explaining is just awesome Just have one question regarding default method As you said java introduces Stream() method in interface List and As we don't want to implement that , java added default method But we generally don't use List interface directly , we use Arraylist or LinkedList So they can simply Add implementation of Stream() method directly in Arraylist and LinkedList, why to add default method??

[@charmishah3712]

You videos are very helpful preparing for Interview to get concepts clear. But only one problem I have I saw lots of video I am still not clear with abstract class and interface difference after the Java 8. Please help me

[@anuragverma9519]

great explanation for interview

[@De0D]

telusko more powerfull than class ,class more powerfull than interface...done ive said it

[@Efocusto]

wonderful work big like

[@akbarmdmca]

what are advantages we are getting by writing static and implemented methods with some examples that will be useful to understand

[@aparnadevi5615]

When the diamond problem occurred to multiple inheritance through interfaces, we defined the the show() method in the concrete sub class again to deal with ambiguity issue that in turn resolves diamond problem. Why can't the same thing be done with multiple inheritance of classes to resolve ambiguity that lead to diamond problem? My doubt is can we do that with classes so that multiple inheritance can be achieved?

[@romanmotovilov129]

Thank you, sir, for a good lesson!!!