Java - Inner Class vs Sub Class

Inner Class

In Java, one can define a new class inside any other class. Such classes are known as Inner class. It is a non-static class, hence, it cannot define any static members in itself. Every instance has access to instance members of containing class. It is of three types:

• Nested Inner Class
• Method Local Inner Class
• Anonymous Inner Class

Generally, it makes code slightly complicated but, it is very useful with abstract window toolkit and AWT(GUI) event handling.

Example:

public class Outer { // outer class
    void showData()
    { // method inside outer class
        ---
    }
    public class Inner { // inner class inside outer class
    }
}

Sub Class

In Java, a subclass is a class that derives/inherited from another class. A subclass inherits everything (like behavior, state of the class, etc. ) from its ancestor classes. For a better understanding of it, we just need to know about the superclass. The superclass is an immediate ancestor of the sub-class. As a subclass has the property of inheriting the properties of an ancestor, hence, it can modify or override the methods of the superclass. For creating a subclass from any other class, we need to use extends clause in the class declaration. 

Example :

// super class
public class Mahindra {
    public Mahindra()
    {
        System.out.println("I am super class");
    }
}

// sub class
public class Scorpio extends Mahindra {
    public Scorpio()
    {
        System.out.println("I am sub class");
    }
}

Difference Table

The difference between the Inner class and sub-class are listed below: