Answer Description: An Interface is implicitly abstract and public. Interfaces with empty bodies are called marker interfaces having certain property or behavior. Examples:java.lang.Cloneable,java.io.Serializable,java.util.EventListener. An interface body can contain constant declarations, method prototype declarations, nested class declarations, and nested interface declarations. Interfaces provide support for multiple inheritance in Java. A class that implements the interfaces is bound to implement all the methods defined in Interface.
Example:
public interface ExampleInterface {
public void functionOne();public long CONSTANT_ONE = 1000;
}