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.
An interface is a contract: The person writing the interface says, " hey, I accept things looking that way ", and the person using the interface says " OK, the class I write looks that way ". An interface is an empty shell. There are only the signatures of the methods, which implies that the methods do not have a body. The interface can't do ...
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.
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.
Hi, interface and type, looks similar but interfaces can use for "Declaration merging" and "Extends and implements" which "type" cannot do.
An interface contains behaviors (Abstract Methods) that a class implements. Unless the class that implements the interface is abstract, all the methods of the interface need to be defined in the class.Since multiple inheritance is not allowed in java so interface is only way to implement multiple inheritance.