Inheritance in Java

Explanation

This Java code demonstrates a concept called Hierarchical Inheritance. In this type of inheritance, a single parent class is inherited by multiple child classes.

Let's break down the code:

1. ClassA: This is the base class or parent class. It contains a single public method dispA() which simply prints "disp() method of ClassA" to the console.

2. ClassB: This is a child class that extends ClassA. This means ClassB inherits all public and protected members (methods and variables) from ClassA. In addition to the inherited dispA() method, ClassB defines its own unique method dispB(), which prints "disp() method of ClassB".

3. ClassC: Similar to ClassB, ClassC also extends ClassA. It's another child class of ClassA. It has its own unique method dispC() that prints "disp() method of ClassC", and it also inherits dispA() from ClassA.

4. ClassD: Yet another child class that extends ClassA. It defines its own method dispD() which prints "disp() method of ClassD", and it also inherits dispA() from ClassA.

5. HierarchicalInheritanceTest: This is the main class where the program execution begins.

   • Inside the main method, an object b of ClassB is created.
   • b.dispB() calls the method defined within ClassB.
   • b.dispA() calls the method inherited from ClassA. This demonstrates that ClassB objects have access to ClassA's methods.
   • Next, an object c of ClassC is created.
   • c.dispA() calls the method inherited by ClassC from ClassA. ClassC objects also have access to ClassA's methods.
   • Finally, an object d of ClassD is created.
   • d.dispD() calls the method defined within ClassD.
   • d.dispA() calls the method inherited by ClassD from ClassA. ClassD objects similarly have access to ClassA's methods.

The core logic is to show that ClassB, ClassC, and ClassD are all independent child classes deriving from the same parent, ClassA, and thus each can access ClassA's methods while also having their own unique functionalities.

Algorithm

The program follows these steps:

1. Define a base class ClassA with a method dispA().
2. Define ClassB which extends ClassA and adds its own method dispB().
3. Define ClassC which extends ClassA and adds its own method dispC().
4. Define ClassD which extends ClassA and adds its own method dispD().
5. In the main method:
   • Create an instance of ClassB.
   • Call dispB() on the ClassB instance.
   • Call dispA() on the ClassB instance (demonstrating inheritance).
   • Create an instance of ClassC.
   • Call dispA() on the ClassC instance (demonstrating inheritance).
   • Create an instance of ClassD.
   • Call dispD() on the ClassD instance.
   • Call dispA() on the ClassD instance (demonstrating inheritance).