@Override annotation in java

What is @Override annotation in java?

Before going to learn @Override annotation learn the concept of Method Overriding.

@Override: Annotation will verify whether a method is available in sub class is exists in a super class or not. If the method is available is subclass and superclass then the compiler will not throw any error.

See below example:

class parent {
    public void display(){
        System.out.println("parent Class Method");
    }
}

class child extends parent{
    @Override
    public void display(){
        System.out.println("child class method");
    }
}

class overrideDemo{
    public static void main(String[] args){
    parent p=new child();
    p.display(); //output: child class method
  }
}

Here, we are creating a reference variable to parent class and object for the child class. And we assigned @Override annotation to display() method in a subclass.
When we compile the @Override method will verify display() is available in the subclass as well as in superclass. A method is an available compiler will not throw any error.

Let see another case:

class parent {
    public void display(){
        System.out.println("parent Class Method");
    }
}
class child extends parent{
    @Override
    public void Display(){
        System.out.println("child class method");
    }
}
class overrideDemo{
    public static void main(String[] args){
    parent p=new child();
    p.display(); //throws error
  }
}

Here,observe by mistake a programmer written a method as Display() in subclass and display() in superclass.

There is a mismatch in method name.

Then compiler will throw error like below:

@Override Annotation

So @override annotation is useful to verify several methods available in sub class as well as in super class.

Please comment below to feedback or ask questions.