An interface is a collection of abstract methods (methods without a body) that define a contract for a class to implement. An interface is defined using the "interface" keyword.
A class that implements an interface must provide an implementation for all of the methods defined in the interface. This is achieved by using the "implements" keyword.
Interfaces are used to define a contract for a class, ensuring that the class implements a set of methods with a specific signature, and it also allows for multiple inheritance and promotes code reusability.
An interface in Java is a blueprint that holds abstract methods and static or final fields. The defining contract, by which the classes implementing this have to abide, can be created through providing concrete implementations of the methods. Some of the most common applications of interfaces include abstraction and support for multiple inheritance. It supports different classes sharing common behaviors without inheriting. This therefore ensures flexibility and loose coupling in the design of the software.
An interface is a group of abstract methods and constants in Java. It helps set rules for classes. It helps in abstraction and provides a class to use multiple interfaces. Since Java 8, it can have default and static methods. The behavior of interfaces is made consistent across classes without forcing a particular way to implement it. It is important in the creation of flexible and modular designs.