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In this part of the Java Video Tutorial I cover interfaces, abstract classes, abstract methods and more.
You need interfaces and abstract classes because Java doesn’t allow you to inherit from more than one other class. You would use an interface when you want to force the user of the interface to create every method in the interface.
You use an abstract method when you need some flexibility.
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Derek Sir u are the best….
Why create the setWheels and setSpeed functions in Vehicles? Aren't those variables already set by the Vehicle constructor?
Great tutorial but too fast too furious 🙁
I'm just glad you speak clear english and don't sound like you are trying to swallow your uvula when you talk.
So basically an interface is the C++ equivalent of a .h file?
Too fast. I didn't understand a little. Lol. xD
Is it important to add 'this.' to the beginning of the variable? Will it work if you just use the variable name?
At 3:54, will "return numOfWheels" do the same thing as "return this.numOfWheels"?
So whats the point? Why do we have to create the interface in the first place? why not just writing the vehicle class??
One thing that may be helpful (at least when using Eclipse)… When you want to add the methods from the interface, you can right-click on the class name and select "add unimplemented methods". This is much easier than manually pulling them in like he did.
Do you have a tutorial for buffered reader and writer to a text file? I need to read a text file and write to a text file.
can interface be a type and if yes what are the advantages of that??
Awesome
I don't know how many of you encounter this video, but if you do – you probably have the same question as the others through these years.
"What's the point?"
Think of how professional organizations work. You need common standards and consistent development across all your teams. This means, when you create a custom object you would like all of them to have some methods such as setters, getters to name a few. This might help for testing and countless other purposes.
The fact that we can enforce a hard template like format only makes work easier, sort of like a rule book that everyone follows.
how come youCrashed() didn't require the abstract declaration?
Hi, I appreciate your effort, and I thank you sincerely, and here are my questions:
Why use an interface if you're going to define everything in a different class?
I know that this might sound dumb, but I'm still new at this: Isn't it possible to employ multiple inheritances by using multiple extended inner classes?
I've read two books on Java, but I still don't get this "implements" business, and extending classes seems, to me, just an economic way to use fewer words and that is all.
Now, I'm certain that I'm wrong. But could you help by answering my questions and directing me to resources that could enlighten me on the subject?
The tutorial helped a lot, you're a good teacher but it's going a bit fast. Maybe that's just because my English is bad and I need time to take it in though. And I'm sure you improved in 5 years 😉 I'll make sure to check out your other video's, thanks again
Dear Derek,
B R E A T H …
u simply talk way too fast! Like in a rush. If you intend to communicate properly … make ur self it easy to follow.
Super helpful..! Thanks
interfaces and abstract classes seem so useless…..
Im a little confused on the difference between abstract classes and interfaces. They both seem to do the same thing, except that abstract classes can have empty methods and implemented methods, whereas interfaces can only have empty methods. Why then is there a need to use abstract classes over interfaces? Is there a reason for methods to have bodies in abstract classes like Crashable versus being implemented in the class that extends the abstract class like Vehicle? If you can omit the bodies of all of methods in interfaces as you did in the interface Drivable, and then define them in your class Drivable, then what is the advantage of using an abstract class?
Loving your videos! I'm surprised you're doing this for free, great explanations! I now completely understand how to build an abstract class and use interfaces. The purpose of adding that functionality to program will eventually come along in my weekly Lab so I'll probably be watching this video a few more. Thanks again!
what is the point of making an abstract class ? we just defined a method in it and called it from main just like we would do with a normal class
How many of you noticed that he plays minecraft.
Take a breath mate..
I'm super confused
Please respond ASAP anyone who knows the fix to this.
Whenever I type something like "public void setWheels(int numWheels){
this.numWheels = numWheels;
}
The line that says "public class Vehicle implements Drivable{"
gives me an error saying "- The type Vehicle must implement the inherited abstract method Drivable.setWheels()
I don't get why class which uses interface has to use whole abstract methods.
interesting video,thanks.
So, interface is for lots of class to have the same style like making name of method?
and doesn't make confusing stuff.. am I right?
well, that does it, min 2:09 and it was as clear as it can possibly be!!!
Derek, you are amazing!!
i didn't understand this tutorial as well as your other ones, could you use some UML diagram to help explain some of these 'simple' concepts?
I didn't understand what IS actually interface, and what does it help the code? Like, in what cases?
Can you please explain what implementing does as I didn't understand that?
But why do I need an Interface if I have to override the methods in my class anyway. It seems to me, that I just have to type stuff twice.
Thanks for replying for my previous doubt!
I agree that we can't use many extends keywords to inherit multiple classes, but why can't we simply create objects of the class that needs to inherited and use it? why is interface coming into play?
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