Why Can Outer Classes Access Inner Class Private Members in Java?

Java Outer Class Access to Inner Class Private Members

Question:

Why do outer classes have the ability to access inner class private instance variables, even though they are declared private? Consider the following code:

class ABC {
    class XYZ {
        private int x = 10;
    }

    public static void main(String[] args) {
        ABC.XYZ xx = new ABC().new XYZ();
        System.out.println("Hello :: " + xx.x); // Why is this allowed?
    }
}

Answer:

Inner classes in Java are unique because they have inherent access to the outer class, including its private members. This is due to the design of inner classes, which are essentially members of their outer class.

The reason behind this access is that inner classes are closely tied to the functionality of their outer class. They encapsulate functionality that is specific to the outer class and would not make sense as a standalone class. Therefore, they have full access to the outer class, including its private members.

This design allows for better encapsulation and modularity within classes. It enables inner classes to operate on the private data of the outer class, which would not be possible with traditional class structures. However, it's important to note that this access is only granted to the inner class and not to other classes or external code.

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