#71 What is Annotation in Java

Check out our courses: Java Full Stack and Spring AI - https://go.telusko.com/JavaSpringAI Coupon: TELUSKO10 (10% Discount) DevOps with AWS: From Basics to Mastery : https://go.telusko.com/DevOpsAWS Coupon: TELUSKO10 (10% Discount) Master Java Spring Development : https://go.telusko.com/masterjava Coupon: TELUSKO20 (20% Discount) For More Queries WhatsApp or Call on : +919008963671 website : https://courses.telusko.com/ In this lecture we are discussing: #1 What is Annotations? #2 What does annotations provide to program? #3 How annotation prevent us from logical error? 1) What is Annotations? -- annotation is type of comment which is used to provide meta data to the compiler and JVM about the program. Basic difference between comment and annotations -- annotation is used to provide meta data to the compiler and JVM about the program but comment is used to provide information to the programmer. 2) What does annotations provide to program and what does for program? -- Annotations are used to provide supplemental information about a program. -- Annotations start with ‘@’. -- Annotations do not change the action of a compiled program. -- Annotations help to associate metadata (information) to the program elements i.e. instance variables, constructors, methods, classes, etc. -- Annotations are not pure comments as they can change the way a program is treated by the compiler. See below code for example. 3) How annotation prevent us from logical error? class A{ public void show(){ System.out.println("In A"); } public void display(){ System.out.println("In A"); } } class B extends A{ @Override public void show(){ System.out.println("In B"); } /* @Override public void displayData(){ System.out.println("In B"); } */ //here you get error because you are not overriding the method of parent class but you are using @Override annotation // if you are thinking I can override display() method but you should defined new method but whenever you mention @override compiler throw error that you are not override the parent class method //it helps to avoid the logical error in the program because logical error is more difficult to find when you use annotation it helps to find the logical error //because solving problem at compile time error is easy than solving problem at runtime } Github repo : https://github.com/navinreddy20/Javacode.git Java:- https://bit.ly/JavaUdemyTelusko Spring:- https://bit.ly/SpringUdemyTelusko More Learning : Java :- https://bit.ly/3x6rr0N Python :- https://bit.ly/3GRc7JX Django :- https://bit.ly/3MmoJK6 JavaScript :- https://bit.ly/3tiAlHo Node JS :- https://bit.ly/3GT4liq Rest Api :-https://bit.ly/3MjhZwt Servlet :- https://bit.ly/3Q7eA7k Spring Framework :- https://bit.ly/3xi7buh Design Patterns in Java :- https://bit.ly/3MocXiq Docker :- https://bit.ly/3xjWzLA Blockchain Tutorial :- https://bit.ly/3NSbOkc Corda Tutorial:- https://bit.ly/3thbUKa Hyperledger Fabric :- https://bit.ly/38RZCRB NoSQL Tutorial :- https://bit.ly/3aJpRuc Mysql Tutorial :- https://bit.ly/3thpr4L Data Structures using Java :- https://bit.ly/3MuJa7S Git Tutorial :- https://bit.ly/3NXyCPu Donation: PayPal Id : navinreddy20 https://www.telusko.com