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Java Method Overriding

Java Method Overriding

Declaring a method in the subclass which already exists there in the parent class is known as method overriding. When a class is inheriting a method from a superclass of its own, then there is an option of overriding the method provided it is not declared as final. The advantage of using overriding is the ability to classify a behavior that’s specific to the child class and the child class can implement a parent class method based on its necessity.

There are certain rules that a programmer should follow in order to implement overriding. These are:
  • In Java, a method can only be written in the child class and not in same class.
  • Argument list should be exactly the same as that of the overridden method of that class.
  • Instance methods can also be overridden if they are inherited by the child class.
  • A constructor cannot be overridden.
  • Final – declared methods cannot be overridden.
  • Any method that is static cannot be used to override.
  • The return type must have to be the same or a subtype of the return type declared in the original overridden method in the parent class.
  • If a method cannot be inherited then it cannot be overridden.
  • A child class within the same package as the instance’s parent class can override any parent class method that is not declared private or final.
  • A child class in a different package can only override the non-final methods declared as public or protected.

Java Program to Demonstrate Method Overriding

Example:
class college {
public void move() {
System.out.println("College is open");
}
}
class univ extends college {
public void move() {
System.out.println("University is open too");
}
}
public class stud {
public static void main(String args[]) {
college a
= new college();
college b
= new univ();
a
.move();
b
.move();
}
}

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