The super keyword in java is a reference variable that is used to refer parent class objects. The super keyword refers to superclass (parent) objects.
The most common use of the super keyword
is to eliminate the confusion between superclasses and subclasses that have
methods with the same name.
Usage of Java super Keyword:
- super can be used to refer immediate parent class instance variable.
Example:
class Vehicle
{
int maxSpeed = 120;
}
class
Car extends Vehicle
{
int maxSpeed = 180;
void display()
{
System.out.println("Maximum
Speed: " + super.maxSpeed); //maxspeed of base
}
}
class
Test
{
public static void main(String[]
args)
{
Car small = new Car();
small.display();
}
}
- super can be used to invoke immediate parent class method.
Example:
class
Person
{
void message()
{
System.out.println("This
is person class");
}
}
class
Student extends Person
{
void message()
{
System.out.println("This
is student class");
}
void display()
{
message();
super.message();
}
}
class
Test
{
public static void main(String
args[])
{
Student s = new
Student();
// calling display() of
Student
s.display();
}
}
- super() can be used to invoke immediate parent class constructor.
Example:
class Person
{
Person()
{
System.out.println("Person
class Constructor");
}
}
class Student extends Person
{
Student()
{
super();
System.out.println("Student
class Constructor");
}
}
class Test
{
public static void
main(String[] args)
{
Student s =
new Student();
}
}
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