Can an Interface extend another Interface?

• A. No, interfaces cannot extend others
• B. Yes, but only one interface at a time
• C. Yes, they can extend multiple interfaces
• D. Only if they are abstract

Answer: (C)

In Java, an interface can indeed extend multiple interfaces. This capability allows for a more flexible and powerful design, enabling a class that implements an interface to inherit the behaviors specified in multiple other interfaces.

When one interface extends another, it inherits all of the abstract methods defined in the extended interfaces. This also applies in cases where multiple interfaces are involved, meaning that an interface can combine the method signatures from several sources, thereby allowing for a more complex and comprehensive contract that implementing classes must fulfill.

This design principle aligns with Java's support for multiple inheritance in terms of interfaces, which allows a class to adhere to various contracts and implement various functionalities. This is particularly useful in large systems where separation of concerns and modular design is critical.

Understanding this concept is important, as it reflects the intention of Java to promote code reuse and flexibility in design through interface-based programming. It is essential for developers to be aware of these capabilities when designing their applications or when working with libraries that leverage multiple interfaces.