Method Overriding in Java

• In Java, method overriding occurs when a subclass (child class) has the same method as the parent class.
• Overriding is a feature that allows a subclass or child class to implement a method that is already provided by one of its super-classes or parent classes.
• When a subclass’s method has the same name, parameters, signature, and return type (or subtype) as a method in its superclass, the subclass’s method is said to override the superclass’s method.
• Method overriding is one of the ways by which java achieves Run Time Polymorphism.

Application of Java Method Overriding:

• Method overriding is a technique for providing a custom implementation of a method that is already provided by its superclass.
• For runtime polymorphism, method overriding is used.

Java Method Overriding Rules:

• The method’s name must match that of the parent class.
• The parameter must be the same as in the parent class.
• An IS-A relationship is required (inheritance).

Method Overriding Example:

class Bank{  
int getRateOfInterest()
  {
    return 0; 
      
  }  
}  
//Creating child classes.  
class SBI extends Bank{  
int getRateOfInterest() 
  {
      return 8;
      
  }  
}  
  
class ICICI extends Bank{  
   int getRateOfInterest()
   {
       return 7;
       
   }  
}  
class AXIS extends Bank{  
   int getRateOfInterest()
   {
       return 9;
       
   }  
}  
//Test class to create objects and call the methods  
class Test2{  
   public static void main(String args[])
   {  
   SBI s=new SBI();  
   ICICI i=new ICICI();  
   AXIS a=new AXIS();  
   System.out.println("SBI Rate of Interest: "+s.getRateOfInterest());  
   System.out.println("ICICI Rate of Interest: "+i.getRateOfInterest());  
   System.out.println("AXIS Rate of Interest: "+a.getRateOfInterest());  
     }  
}  

Output:

SBI Rate of Interest: 8
ICICI Rate of Interest: 7
AXIS Rate of Interest: 9

Points to remember:

• The super keyword can be used to invoke the parent class method in an overriding method.
• We can’t override the constructor because parent and child classes can’t have the same constructor name (The constructor name must always be the same as the Class name).
• Overriding a static method is not possible. Runtime polymorphism can prove it, so we’ll learn it later.
• A static method is bound to a class, whereas an instance method is bound to an object, therefore a static method cannot be overridden.
• Because main is a static method, it cannot be overridden.

Note: also read about the Method Overloading

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