Super keyword in java with Example
The super keyword is a reference variable which refers to its parent
class, which means inheritance must be there. Same as this keyword in java, which
refers to the same class object. We can say that whenever the base class version of
the method is called which is overridden in the child class. Here super can
access the immediate parent class method and variables.
For example, consider the following program
class Parent
{
void display()
{
System.out.println
(“I am from parent class”);
}
}
class Child extends Parent
{
void display()
{
display(); // it lead to recursion
System.out.println
(“I am from Child class”);
}
}
When we display() method in child class lead to recursion.
public class RunPrg
{
public static void
main(String args[])
{
Child ob=new Child();
ob.display ();
}
}
To avoid recursion we need a super keyword for calling the parent class
method. In the following child class version, we used the super in display() method.
public class Child extends Parent
{
void display()
{
super.display(); // use of super to call the parent class
method
System.out.println
("I am from Child class");
}
}
the super keyword can be used to refer parent class instance variable.
The instance variable of the parent
class can be accessed in the child class with the help of the super keyword.
public class Parent
{
String team="KKR";
}
After the parent class, we define
the child class, which calls the parent class instance variable with the super
keyword.
public class Child extends Parent
{
String team="RCB";
void display()
{
System.out.println ("Team of
Parent=" + super.team);
System.out.println
("Team of Child =" + team);
}
}
We need to run the child with
RunPrg class where the main() method defined.
public class RunPrg
{
public static void main(String args[])
{
Child ob=new Child();
ob.display();
}
}
Output
Team of Parent=KKR
Team of Child =RCB
the super keyword can be used to refer parent class constructor
with the help of the super keyword, we can access the parent class constructor
as follows
public class Parent
{
Parent()
{
System.out.println("I am parent class constructor");
}
}
Note: Call to super() must be
first the statement in the child (drive) Class constructor.
Below is a child class example
public class Child extends Parent
{
Child()
{
super(); // called the
parent class constructor
System.out.println("I am Child class constructor");
}
}
And then run the program with another class as follows
public class RunPrg
{
public static void
main(String args[])
{
Child ob=new
Child();
}
}
Output will as
I am parent class constructor
I am Child class constructor
More Java program
