Methods are also declared in interfaces. A method declared in an interface does not define the actual behavior of the method; they do not contain the code. They have only the head of the method; in other words, they are abstract implicitly. Although nobody does, you may even use the abstract keyword in an interface when you define a method.
Interfaces look very similar to classes, but instead of using the class keyword, we use the interface keyword. Because interfaces are mainly used to define methods, the methods are public if no modifier is used.
Interfaces can also define fields, but since interfaces cannot have instances (only implementing classes can have instances), these fields are all static and they also have to be final ...
