Lecture 8: Inheritance in Java смотреть онлайн

Inheritance in Java:
• Mechanism of deriving a new class from an old one is called inheritance. The old class is known as base class or super class or parent class. And new one is called subclass or derived class or child class.


Sub classing is a Relationship:
• In programming, we can often create a model of something e.g. Employee, and then need a more specialized version of that original model e.g. Manager.
• Clearly a manager actually is an employee, but an employee with additional features.


When only one class is derived from a single super class, the type of inheritance is called as single inheritance.
class A
{
int a,b;
A()
{
a=10;
b=20;
}
void displayA()
{
System.out.println(“value of a is :”+a);
System.out.println(“value of b is :”+b);
}
}
class B extends A
{
int k;
B()
{
k = 30;
}
void displayB()
{
System.out.println(“value of a is :”+a);
System.out.println(“value of b is :”+b);
System.out.println(“value of k is :”+k);
}
}
class InheritDemo
{
public static void main(String args[])
{
A ob1 = new A();
B ob2 = new B();
System.out.println (“Detail of class A”);
ob1. displayA();
System.out.println (“Details of class B”);
ob2. displayB();
}
}
Output:
Detail of class A
value of a is = 10
value of b is = 20
Details of class B
value of a is = 10
value of b is = 20
value of k is = 30

Here, only default constructor is there so that B ob2 = new B(); calls the constructor of super class also.
Note that, a class member that has been declared as private will remain private to its class and not inherited in child class.



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Prof. Amol M. Jagtap
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