Method Overriding in Java

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What is Method Overriding in Java? Difference between Method Overriding and Method Overloading in Java – Java Tutorial

Solution:

Method overriding is a mechanism in which a subclass inherits the methods of a superclass and sometimes the subclass modifies the implementation of a method defined in the superclass.

Video Tutorial – Method Overriding in Java

The method of superclass which gets modified in a subclass has the same name and type signature.

The overridden method must be called from the subclass.

The overridden method must be called from the subclass.

Consider following Java Program, in which the method (named as fun ) in which a is assigned with some value is modified in the derived class.

When an overridden method is called from within a subclass, it will always refer to the version of that method re-defined by the subclass.

The version of the method defined by the superclass will be hidden.

Programming example to demonstrate method overriding

class A 
{ 
	int a=0; 
	void fun(int i) 
	{ 
		this.a=i; 
	} 
} 
class B extends A 
{
	int b; 
	void fun(int i) 
	{ 
		int c; 
		b=20; 
		super.fun(i+5);
		System.out.println(“The     value of a:“+a); 
		System.out.println(“The value of b:"+b); 
		c=a*b; 
		System.out.println("The value of c: "+c); 
	} 
} 
class OverrideDemo 
{ 
	public static void main(String args[]) 
	{ 
		B obj_B=new B(); 
		obj_B.fun(10);  //function re-defined in derived class
	}
}

Output:

The value of a: 15

The value of b: 20

The value of c: 300

Program Explanation

 In the above program, there are two classes – class A and class B.

Class A acts as a superclass and class B acts as a subclass.

In class A, a method fun is defined in which the variable a is assigned with some value.

In the derived class B, we use the same function name fun in which, we make use of a super keyword to access the variable a, and then it is multiplied by b and the result of multiplication will be printed.

Another Example to demonstrate Method overring in Java

class A
{
   void display()
   {
      System.out.println("Super class method");
    }
}

class B extends A
{
   void display()
   {
       super.display();
       System.out.println("Derived class method");
   }
}

public class MethodOverriding 
{
   public static void main(String args[])
   {
     B obj = new B();
     obj.display();
   }
}

Output:

Super class method

Derived class method

Difference between Method Overloading and Method Overriding in Java

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