What is code reusability? Explain different mechanism to reuse the code in java.

 Code reusability is the ability to reuse existing code to perform a particular task without having to rewrite it from scratch. It is an important concept in software engineering as it can save time and effort in software development and maintenance.

In Java, there are several mechanisms to achieve code reusability, including:

1. Inheritance: Inheritance is a mechanism in which a new class is created by inheriting the properties of an existing class. The new class is called a subclass or derived class, and the existing class is called a superclass or base class. The subclass can reuse the code of the superclass, and also add its own code as necessary.
2. Composition: Composition is a mechanism in which a class contains one or more objects of another class. By using composition, a class can reuse the functionality of another class without inheriting from it. This allows for more flexible and modular code design.
3. Interfaces: An interface is a collection of abstract methods that define a set of behaviors. A class can implement an interface to provide the implementation of those behaviors. By using interfaces, different classes can share a common set of behaviors, which can be reused in other parts of the program.
4. Packages: A package is a collection of related classes and interfaces that can be reused in other parts of the program. By grouping related code into packages, the code can be more easily managed and reused in different parts of the program.
5. Generic programming: Generic programming is a mechanism in which a class or method can be designed to work with any type of data, rather than being restricted to a specific type. By using generic programming, code can be reused across different data types, improving code reusability and flexibility.

Overall, these mechanisms provide different ways to achieve code reusability in Java, allowing developers to build more efficient, maintainable, and scalable software systems.