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Super Keyword in Java

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Super keyword in Java
Super Keyword in java used to refers the super class object. super keyword is a reference variable in java programming language . super keyword used in inheritance. 
Note : We can not use the super keyword inside the static area .

Super Keyword Usage in java
Important usages of super keyword in java as follows 
  • Super keyword is used to call the super class instance variables.
  • Super keyword is used to call the super class method.
  • Super keyword is used to call the super class constructor.
Use (1) : Super keyword is used to call the super class instance variables.

Syntax
class Bike
{  
String brand="Hero-Honda";  
}  
class Car extends Bike
{  
String brand="Maruti";  
void brandName()
{  
System.out.println(brand);
System.out.println(super.brand);// Use of super keyword 
}  
}  
class Drive
{  
public static void main(String args[])
{  
Car d=new Car();  
d.brandName();  


}
Output : Maruti
              Hero-Honda

Use (2)Super keyword is used to call the super class method

Syntax
class Bike 
{  
void speed()
{
System.out.println("Bike speed is 100 kmph");
}  
}  
class Car extends Bike
{  
void speed()
{
System.out.println("Car speed is 140 kmph");
}   
void checkSpeed()
{  
speed();
super.speed();  
}  
}  
class FinalSpeed{  
public static void main(String args[])
{  
Car d=new Car();  
d.checkSpeed();  


}
}  
OutputCar speed is 140 kmph
            Bike speed is 100 kmph

Use (3) Super keyword is used to call the super class constructor.

Rule
1-Super keyword must be first statement inside the constructor.
2- Inside the constructor we can not use both super keyword and this keyword.
3- Inside the Constructor we can not use 2 super keyword .
Syntax
class Bike
{  
Bike()
{
System.out.println("Speed is 80 Kmph");
}  
}  
class Car extends Bike
{  
Car()
{  
super();  
System.out.println("Speed is 120 kmph");  
}  
}  
class SpeedTest
{  
public static void main(String args[])
{  
Car d=new Car();  


}
}  
Output : Speed is 80 kmph
             Speed is 120 kmph

Note : When we not declare any super keyword inside the constructor ?
If we are not declaring any super keyword inside the constructor then the compiler generate the super keyword with 0-argument .Compiler generated super keyword not visible to user.
Syntax
class Bike
{  
Bike()
{
System.out.println("Speed is 80 Kmph");
}  
}  
class Car extends Bike
{  
Car()
{  
super();  //Compiler generated super keyword 
System.out.println("Speed is 120 kmph");  
}  
}  
class SpeedTest
{  
public static void main(String args[])
{  
Car d=new Car();  
}

Output : Speed is 80 kmph

             Speed is 120 kmph

Important Points : Super Keywords

  • To call parent class instance variable use super keyword.
  • To Call Parent class method use Super keyword 
  • To Call Parent Class constructor use super keyword .
  • Super keyword must be first statement in constructor .
  • We can declare only one super keyword inside the the constructor .
  • We can not declare both this keyword and super keyword inside the constructor .
  • We can not used the super keyword inside the static area.



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Hope!!! The above lesson of java super keyword helpful for you ...

Thank You !
Sandeep Yadav

Tags : Super keyword in java , java super keyword , usages of java super keyword , example of super keyword 
Super Keyword in Java




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