How Can We Mimic C 's `friend` Functionality in Java?

Mimicking C 's 'friend' Concept in Java

In object-oriented programming, the 'friend' concept allows classes in different packages to access each other's non-public members. While Java lacks an explicit 'friend' mechanism, there is a clever workaround to achieve similar functionality.

Consider two classes, Romeo and Juliet, belonging to different packages. To allow Romeo to access non-public methods of Juliet, follow these steps:

1. Create a Token Class in Romeo's Package: Define a public class Love within Romeo's package, with a private constructor. This class acts as a "signature security" token.
2. Create a Public Method in Juliet's Package: Define a public method cuddle in Juliet's package that accepts an argument of type Love.
3. Restrict Cuddle Access: Within the cuddle method, check if the passed Love token is not null. Otherwise, it ensures that only Romeo can call cuddle.
4. Access the Cuddle Method from Romeo: Define a public static method cuddleJuliet in Romeo that constructs an instance of Love and passes it to Juliet.cuddle.

This technique allows Romeo to access Juliet's non-public methods without making it a subclass of Juliet. By passing a unique token, it ensures that only Romeo can call those methods, replicating the behavior of the C 'friend' concept.

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