Super and Final in java
                     Object Oriented Using Java -
Super and Final Keyword
PRESENTED BY:
ANSHU SHARMA
SUPER KEYWORD IN JAVA
 The super keyword in Java is a reference variable 
which is used to refer immediate parent class object.
 Whenever you create the instance of subclass, an 
instance of parent class is created implicitly which is 
referred by super reference variable.
 It is used to call superclass methods, and to access 
the superclass constructor.
 The most common use of the super keyword is to 
eliminate the confusion between superclasses and 
subclasses that have methods with the same name.
USE OF SUPER KEYWORD
 super can be used to refer immediate parent class 
instance variable.
 super can be used to invoke immediate parent class 
method.
 super() can be used to invoke immediate parent 
class constructor.
 super () calls the parent class constructor with no 
argument. 
 super.methodname calls method from parents class.
 It is used to call the parents class variable.
USE OF SUPER KEYWORD
 
EXAMPLES: 1) SUPER IS USED TO REFER
 IMMEDIATE PARENT CLASS INSTANCE VARIABLE.
 We can use super keyword to access the data member or field of 
parent class. It is used if parent class and child class have same fields.
class vehicle{  
String color="white";  
}  
class  car extends  vehicle{  
String color="black";  
void printColor(){  
System.out.println(color);//prints color of car class  
System.out.println(super.color);//prints color of vehicle class  
}  
}  
EXAMPLE CONTD.
class TestSuper1{  
public static void main(String args[]){  
car c=new car();  
c.printColor(); 
In the above example, vehicle and car both classes 
have a common property color. If we print color 
property, it will print the color of current class by 
default. To access the parent property, we need to 
use super keyword.
 
2) SUPER CAN BE USED TO
 INVOKE PARENT CLASS METHOD
 The super keyword can also be used to invoke parent class 
method. It should be used if subclass contains the same method 
as parent class. In other words, it is used if method is overridden.
class person{  
void eat(){System.out.println("eating...");}  
}  
class  student extends person{  
void eat(){System.out.println("eating ...");}  
void read(){System.out.println(“Reading...");}  
void work(){  
super.eat();  
read();  
}  
}  
EXAMPLE CONTD.
class TestSuper2{  
public static void main(String args[]){  
student d=new student();  
d.work();  
}}  
In the above example person and student both classes 
have eat() method if we call eat() method from 
student class, it will call the eat() method of student 
class by default because priority is given to local. 
3) SUPER IS USED TO INVOKE
 PARENT CLASS CONSTRUCTOR.
 The super keyword can also be used to invoke the parent class 
constructor. Let's see a simple example:
class  person{  
person()
{
System.out.println(“person class");}  
}  
class student extends person{  
student()
{  
super();  
System.out.println(“student class");  
}  
}  
EXAMPLE CONTD.
class TestSuper3{  
public static void main(String args[]){  
student d=new student();  
}}  
Output:
person class
Student class 
 
As we know well that default constructor is provided by compiler 
automatically if there is no constructor. But, it also adds super() 
as the first statement.
FINAL KEYWORD IN JAVA
 The final keyword in java is used to restrict the 
user. The java final keyword can be used in many 
context. Final can be:
• A variable
• A method
• A class
 The final keyword can be applied with the variables, 
a final variable that have no value it is called blank 
final variable or uninitialized final variable. It can be 
initialized in the constructor only. The blank final 
variable can be static also which will be initialized in 
the static block only. 
FINAL KEYWORD IN JAVA
  
1) JAVA FINAL VARIABLE
 If you make any variable as final, you cannot 
change the value of final variable(It will be 
constant).
Example of final variable
 There is a final variable speedlimit, we are 
going to change the value of this variable, 
but It can't be changed because final variable 
once assigned a value can never be changed.
 
EXAMPLE:
class Bike9{  
 final int speedlimit=90;//final variable  
 void run(){  
  speedlimit=400;  
 }  
 public static void main(String args[]){  
 Bike9 obj=new  Bike9();  
 obj.run();  
 }  
}//end of class
Output:
Compile Time Error
 
  
2) JAVA FINAL METHOD
If you make any method as final, you cannot override it.
Example of final method
 
class Bike{  
  final void run()
{
System.out.println("running");}  
}  
     
class Honda extends Bike{  
   void run()
{
System.out.println("running safely with 100kmph");
}  
     
 
EXAMPLE CONTD.
  public static void main(String args[])
   {  
   Honda honda= new Honda();  
   honda.run();  
   }  
}
Output:
Compile Time Error
 
  
3) JAVA FINAL CLASS
 
If you make any class as final, you cannot extend it.
Example of final class
 
final class Bike{}  
  
class Honda1 extends Bike{  
  void run(){System.out.println("running safely with 100kmph");}  
    
  public static void main(String args[]){  
  Honda1 honda= new Honda1();  
  honda.run();  
  }  
}  
Output:
Compile Time Error
Thankyou