Inheritance is a key feature of object-oriented programming that allows a new class to be based on an existing class, inheriting its attributes and behaviors. Here are some of the reasons why inheritance is used in Java:

1. Code Reusability: Inheritance allows us to reuse existing code, reducing the amount of code we need to write. When we inherit from an existing class, we automatically get access to all of its public and protected members, including fields, methods, and constructors.

2. Polymorphism: Inheritance is also useful for achieving polymorphism, which allows us to write more generic and flexible code. Polymorphism allows objects of different classes to be treated as if they were of the same type, simplifying the code and making it more extensible.

3. Extensibility: Inheritance also allows us to extend existing classes, adding new features or modifying existing ones. By extending an existing class, we can build on its functionality, adding new methods or fields, or overriding existing ones.

4. Maintainability: Inheritance can also improve the maintainability of our code by making it more modular and easier to understand. By inheriting from an existing class, we can create classes that are more specialized and easier to manage, reducing the complexity of the code.

5. Abstraction: Inheritance also provides a way to create abstract classes, which define a set of common attributes and behaviors that can be inherited by other classes. Abstract classes provide a way to define a common interface for a group of related classes, simplifying the code and making it easier to modify and maintain.

In summary, inheritance is a powerful tool that can help us write more modular, flexible, and maintainable code. By allowing us to reuse existing code, achieve polymorphism, and extend existing classes, inheritance can help us write more efficient and effective programs.