An interface promises nothing about an action! The source of the confusion is that in most languages, if you have an interface type that defines a set of methods, the class that implements it "repeats" the same methods (but provides definition), so the interface looks like a skeleton or an outline of the class.
The first word in the interface value points at what I call an interface table or itable (pronounced i-table; in the runtime sources, the C implementation name is Itab). The itable begins with some metadata about the types involved and then becomes a list of function pointers.
42 The interface keyword indicates that you are declaring a traditional interface class in Java. The @interface keyword is used to declare a new annotation type. See docs.oracle tutorial on annotations for a description of the syntax. See the JLS if you really want to get into the details of what @interface means.
An interface is a good example of loose coupling (dynamic polymorphism/dynamic binding) An interface implements polymorphism and abstraction.It tells what to do but how to do is defined by the implementing class.
If both interfaces have a method of exactly the same name and signature, the implementing class can implement both interface methods with a single concrete method. However, if the semantic contracts of the two interface method are contradicting, you've pretty much lost; you cannot implement both interfaces in a single class then.
Yes, your example of defining an interface only for the particular items would be a more useful way to do it. It would be quite rare to have an array of items, but not want to conveniently reference a single item. Using a real array also exposes .length on the interface, which will probably be used quite often.
An informative annotation type used to indicate that an interface type declaration is intended to be a functional interface as defined by the Java Language Specification. and the use case Note that instances of functional interfaces can be created with lambda expressions, method references, or constructor references.
An interface in java is a special type of Abstract class, the Interface provided the 100% Abstraction but since the java introduce new features in java 8 the meaning of whole Interface is change.
In Dart there is a concept of implicit interfaces. Every class implicitly defines an interface containing all the instance members of the class and of any interfaces it implements. If you want to create a class A that supports class B’s API without inheriting B’s implementation, class A should implement the B interface. A class implements one or more interfaces by declaring them in an ...
An Interface is more of a high level architectural tool (which becomes clearer if you start to grasp design patterns) - an Abstract has a foot in both camps and can perform some of the dirty work too. Why use one over the other? The former allows for a more concrete definition of descendants - the latter allows for greater polymorphism.
