Concept of interfaces in Java

In Java, an interface is an abstract type that defines operations and behavior that a class or object should have, but does not provide implementation details.

Interfaces can contain constants and abstract methods. Constants are member variables declared in the interface, and their values cannot be changed in the interface. Abstract methods are method declarations without implementations. Classes that implement the interface must implement all the abstract methods declared in the interface.

An interface is defined using the keyword “interface” in Java, and can be implemented by classes or extended by other interfaces. A class can implement multiple interfaces, enabling multiple inheritance.

The main purpose of interfaces is to define a set of standards or contracts, allowing multiple different classes to achieve a common goal by implementing the same interface. Through interfaces, polymorphism can be achieved, improving the flexibility and scalability of the code.

In summary, interfaces in Java are abstract types used to define the operations and behaviors that classes or objects should have. By implementing interfaces, classes can achieve the effect of multiple inheritance, thus enhancing the flexibility and scalability of the code.