Inner Classes in Java

Introduction

In Java, an inner class is a class that is defined within another class. It provides a way to logically group classes that are only used in one place, which can improve code organization and encapsulation. Inner classes have access to the members of the outer class, including private members, and can be instantiated only within the scope of the outer class.

In this article, we will explore an example of an inner class in Java and understand how it works.

Key Concepts

Before diving into the code example, let's clarify a few key concepts related to inner classes:

• Outer Class: The class that contains the inner class is called the outer class. It provides a context for the inner class and can access its members.
• Inner Class: The class defined within the outer class is called the inner class. It has access to the members of the outer class and can be instantiated only within the scope of the outer class.
• Access Modifiers: Inner classes can have different access modifiers, such as public, private, protected, or default. The access modifier determines the visibility of the inner class outside the outer class.

Code Structure

class Outer {
    String so = "This is Outer Class";
    
    void display() {
        System.out.println(so);
    }
    
    void test() {
        Inner inner = new Inner();
        inner.display();
    }
    
    // This is an inner class
    class Inner {
        String si = "This is Inner Class";
        
        void display() {
            System.out.println(si);
        }
    }
}

class InnerClassDemo {
    public static void main(String args[]) {
        Outer outer = new Outer();
        outer.display();
        outer.test();
    }
}

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