Hierarchical Inheritance in Java with Example

In this inheritance multiple classes inherits from a single class i.e there is one super class and multiple sub classes. As we can see from the below diagram when a same class is having more than one sub class (or) more than one sub class has the same parent is called as Hierarchical Inheritance.

Here ClassA acts as the parent for sub classes ClassB, ClassC and ClassD. Lets take a look into the below code.

public class ClassA 
{
    public void dispA()
    {
        System.out.println("disp() method of ClassA");
    }
}
public class ClassB extends ClassA 
{
    public void dispB()
    {
        System.out.println("disp() method of ClassB");
    }
}
public class ClassC extends ClassA
{
    public void dispC()
    {
        System.out.println("disp() method of ClassC");
    }
}
public class ClassD extends ClassA
{
    public void dispD()
    {
        System.out.println("disp() method of ClassD");
    }
}
public class HierarchicalInheritanceTest 
{
    public static void main(String args[])
    {
        //Assigning ClassB object to ClassB reference
        ClassB b = new ClassB();
        //call dispB() method of ClassB
        b.dispB();
        //call dispA() method of ClassA
        b.dispA();
        
        
        //Assigning ClassC object to ClassC reference
        ClassC c = new ClassC();
        //call dispC() method of ClassC
        c.dispC();
        //call dispA() method of ClassA
        c.dispA();
        
        //Assigning ClassD object to ClassD reference
        ClassD d = new ClassD();
        //call dispD() method of ClassD
        d.dispD();
        //call dispA() method of ClassA
        d.dispA();
    }
}

Output :

disp() method of ClassB
disp() method of ClassA
disp() method of ClassC
disp() method of ClassA
disp() method of ClassD
disp() method of ClassA