Super keyword in java

Super Keyword in Java:-

  • The super keyword in java is a reference variable that is used to refer parent class objects.  
  • The keyword “super” came into the picture with the concept of Inheritance 

 Use of super keyword is as followed :-

1. Use of super with variables: 
2. Use of super with methods: 
3. Use of Super with Constructors 
 
   1. Use of super with variables: 
  •  This scenario occurs when a derived class and base class has same data members.
  • In that case there is a possibility of ambiguity for the JVM. 
  • We can understand it more clearly using this code snippet 
 
class Animal
{  

String color="white";  

} 

 class Dog extends Animal

{  

String color="black";  

void printColor()

{  

System.out.println(color); 

System.out.println(super.color);//prints color of Animal class  

}  

} 

 class TestSuper1

{  

public static void main(String args[])

{  

Dog d=new Dog();  

d.printColor();  

}

} 

2. Use of super with methods: 

  • This is used when we want to call parent class method. 

  • So whenever a parent and child class have same named methods then to resolve ambiguity we use super keyword. 

  • This code snippet helps to understand the said usage of super keyword.

 

class Animal

{  

void eat(){System.out.println("eating...");

}  

}  

class Dog extends Animal

{  

void eat()

{

System.out.println("eating bread...");

}  

void bark()

{

System.out.println("barking...");

}  

void work(){  

super.eat();  

bark();  

} 

 } 

 class TestSuper2{  

public static void main(String args[])

{  

Dog d=new Dog();  

d.work();  

}

} 

3. Use of super with constructors:  

  • super keyword can also be used to access the parent class constructor. 

  • One more important thing is that, ‘’super’ can call both parametric as well as non parametric constructors depending upon the situation. 

  • Following is the code snippet to explain the above concept:

 

class Animal

{  

Animal()

{

System.out.println("animal is created");

}  

}  

class Dog extends Animal

{  

Dog()

{  

super();  

System.out.println("dog is created");  

}  

}  

class TestSuper3{  

public static void main(String args[])

{  

Dog d=new Dog();  

}

} 

 

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