Generics in Java
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- Опубліковано 1 гру 2016
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In a nutshell, generics enable types (classes and interfaces) to be parameters when defining classes, interfaces and methods.
Much like the more familiar formal parameters used in method declarations, type parameters provide a way for you to re-use the same code with different inputs.
The difference is that the inputs to formal parameters are values, while the inputs to type parameters are types.
Code that uses generics has many benefits over non-generic code:
- Stronger type checks at compile time.
A Java compiler applies strong type checking to generic code and issues errors if the code violates type safety.
Fixing compile-time errors is easier than fixing runtime errors, which can be difficult to find.
- Elimination of casts.
- Enabling programmers to implement generic algorithms.
By using generics, programmers can implement generic algorithms that work on collections of different types, can be customized, and are type safe and easier to read.
In this video we will see :
- What is Generics
- What is Type-safe Language
- How to achieve type safety
- An example or program of Generics implementation in Java
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Sir in this lockdown I have learned a lot in programming just because of you. Thank you so much
Best Java channel. Straightforward explanation, with code live demonstrated. You are sure to learn just by watching this. I learned from you in Spring Boot, REST services, and Java core APIs. Thank you so much!
Telesko is good but I would like you to check Java Brains channel of Kaushik, your view might change
Very straight-forward and easy to understand. Thanks for the content!
he explained it in very simple manner now i understand this concept hope he will upload more complex way to define generic
Thank you so much! I've been looking all over the internet for this and none of them were as good and straightforward as this! Thank You SO MUCH!
sir how to do that you have done at 10:49 to see which class/interface extends which class
when i do that in eclipse by holding control something different shows up "source not found
"
7:35 mind blown; thank you for this video
This guy is awesome, he really likes teaching which is highly appreciate it.
Hi Telusko,
Could you please tell us how to access the java provided classes like List.class and Float.class. I use Eclipse as well but haven't figured it out yet.
While doing so I am getting the following error:
The JAR file C:\Program File\Java\jre1.8.0_201\lib
t.jar has no source attachment.
your title music is damn scary if you have seen haunted on discovery channel
Read this as I was thinking the same thing. I'm dying over hear with that into music. LOL
as scary as generics in java
@@cori2852 :))))))
Thank you so much, it's very easy to understand!
This is the single most important video if you want to be clear about Generics...Thank you!!
This really is the best video on Generics, I love it!
I dont know why, but i am not being able to jump to implementation of any java inbuilt classes?
Any help!
What if I want to use everything related to T (aka, both the supers and subclasses of T and also T itself?)
Great video, now I understand the concept. Thanks a lot!
I was always confused with "? extends ..." & "? super ...." but now it is clear to me. Thanks Navin Sir.
Awesome bro... Best Video I ever saw for Generics... Thanx man.
Thank you so much Bro for your explanation. Your video resolved many of my confusion that even my lecturer was not able to solve coz she did not understand my confusion. Generics is much more clear now for me.
need help confusion on following declaration why ..
1) class CalendarDate implements Comparable (when we implement Comparable we write in the end )
2) class OrderPair implements Pair .... (in user define interface we write after Class can somebody explain it)
Really nice explaination. Thanks for all the details!
The beauty of java is that before solving clients problem you have to solve java problems.
Thank You, your lesson helped me a lot!
Thanks lot... for exact concept of java & all telusko videos to teach all technologies
in method definition of public void demo(ArrayList
I knew about Telusko from its inception but never liked or followed. But after seeing this one single lecture. Hands down never judge a book by its cover
100% explained ! Knowledge necessary for heavy solutions. Thank you. Keep on.
Another great video that helped me with understanding my school homework. Thank you sir.
Thank you so much, your generics explanation is awesome.
u have some enormous talent sir...plz continue this job..all the best
Good leason.
I was easily able to understand the generics.
Thanks.
Very detailed explanation. THANK YOU!!!!
Now this was a good video. You didn't cut it too short and leave out some of the nuances like others do. Now i'ma go lookup that ? thing and Super.
Thanks a ton Navin. You are the best!
sir in Hash map can we enter only key and values or we can enter one key no of values (like = sid,sname,address and phone )
lucid explanation. I have been watching ur videos for quite a while now. Thanks Navin Reddy. ur amazing.
Well explained. Thank you very much
The best explanation for Generics and Collection interface and Collections classes
what if I want to use student class eg: Container obj=new Container(); how will i write my student class then? i am confused
many many thanks ... superb video
I can't understand this in my class but here I've cleared all of my confusions in one shot ❤❤❤❤
Thank u sir ❤❤
Even I m non it student, I m getting this concept clearly
Thanks to telusko🙏👍
Thank You Navin, BIG Help!
You are simply awesome Navin
This man is great I wish you a healthy and happy life and thanks for sharing.
why LIST interface methods are not asked to be implemented? rather its optional
but when we create a new interface and add some methods, they need to be used mandatorily.
Excellent!! Thank you very much indeed. .
Hello anna! just want to know about something which I encountered while I was coding my own Collections(say linkedList). So, I used and everything was working fine, however, when I tried to write a method for finding minimum in Linkedlist, compiler keeps throwing errors(as finding minimum wouldn't be possible if the type were (T=)String. So, I want just this method to accept Integer or any Number values and whenever the type doesn't fit it should neglect it. How can I do so?
Its similar to temlate in C++. They changed template to generics
clear explanation , thanks mate.
Just asking, but what is the point of adding getters and setters in the class Container? From what I have tested so far, everything worked fine without those..
Everything worked fine without those because getter and setter for value were not used/called anywhere in the code.
Point for adding those was just to show how generics works.
For example, if you made object obj, like in the video:
Container obj = new Container();
and you want to set value for it:
obj.setValue("Java");
then compiler will know that T is String,
public void setValue(T value); ----> public void setValue(String value);
Thank You Sir🙏🏻. You taught it very well .
Hello sir! I need to know which subclass is sorted hashMap Or hashTable... ???
In case of....
Map m= new HashMap(); or HashTable() ;
Thank you!! Excellent explanation :)
Great video. Thank you so much.
Could you tell me how to access the java proviced classes like List.class and Float.class. I use Eclipse as well but haven't figured it out yet.
Do you mean: How do you go to the implementation of List? Just right click --> Go To --> Implementation (or [Ctrl]+[Alt]+[B]).
You are really great my friend, tank you for your videos
concise and clear, thanks
such a awesome video. I loved it.
Entities have different type of class. Student class, employee class. Thanks i need to populate data from database as List
Naveen sir your presentation is simple and understandable
Awesome Video I have ever seen ,
in short
in 5 min
Complete
Compaq
great explanation, thanks.
Hello Sir,
Thanks for videos really very nice. I tried to check same code in my exclipse ide but I am getting an error when super keyword is used with Number and when passed Integer to ArrayList
/* Code start here */
import java.util.ArrayList;
import java.util.List;
class Test{
public static void main(String args[]){
Container obj =new Container();
obj.value=9;
obj.show();
obj.demo(new ArrayList()); //Getting error here but as per your lecture this will not happen
}
}
class Container{
T value;
public void show(){
System.out.println(value.getClass().getName());
}
public void demo(ArrayList
thank you so much for this!
Great method of teaching.
Love the way you say "Dabl" & "GettaSetta" :D
9:05 when he laughed?
Can you show a real example of using super keyword? I understood that it is used as constraint for concrete type, but when and where I should use it?
Use '? super T‘ whenever you want to indicate a type which is a super-type of 'T'.
This helped, thanks :)
It's clear, thank you.
BEST ever
its good that such people do exist.#ilovetelusko
It was good but please discuss about generic method and uses of generics in combination with reflection
It showing an output is true is type is matching other wise showing an error what we can do to print a exact values
what's T extends Comparable ?
4:12 I didn't understand line 18...what is it doing?
13:05 didn't understand
how to get rid of Raw class warning without suppressing it.
excellent video!!!!
Bhai Mere mazza aa gya yaar
WOW that was a great video!
Well Explained
The error at 3:37 is about Integer.parse() and not the List.add
Excellent Video
Amazing content!!
very helpful tnx a lot
I would like to donate but i want to use my paypal. is it possible ?
great explanation
sir will u please provide the practical session videos
CAN WE USE ? WHILE CREATING GENERIC CLASSES
Why can't we use T or K or anything in place of '?'.
Thanks I love it 🤝
Sir you showing list.class but how to go it sit
thank you. It was effective
Nice explanation
Sir what was that - value.getClass().getName() ????
class Container can take any type as parameter (T),
when you are creating an object of class Container you can specify which type inside ,
for example:
Container obj = new Container(9);
Container obj1 = new Container("Java");
next, in Container class we have show() method
when we call that method on obj or obj1 it will return type of obj and obj1 by using getClass().getName()
try it in your IDE, type value press . and see list of methods you can use
docs.oracle.com/javase/8/docs/api/java/lang/Object.html#getClass--
docs.oracle.com/javase/8/docs/api/java/lang/Class.html#getName--
very good thanks
Excellent!!!!!
Nice vid man!
what is the differenes of list< T > with list< ? > ?
list -> where T can be any fixed type and which is entered by you as a programmer and than it can not be changes in the middle
list -> this is wild card, which can be anything. usually used when you dont know whats going to come up
value.getclass().getname () . what does it do ?
didn't get it
It returns you the name of the objects class.
Thank you for this well made explanation