Interface Bounceable

D

dsfextremePJ 3 de jul. de 2006

“marcelomarqueti”:
Pessoal,

Alguem pode me dar uma dica o que é uma interface bouceable. .tipo eu uso interfaces normais … nunca utilizei bounce, qual seria a diferença e sua aplicação ?

Obrigado !!!. . .

É isso !

When you create an interface, you?re defining a contract for what a class can do,
without saying anything about how the class will do it. An interface is a contract.
You could write an interface Bounceable, for example, that says in effect, ?This
is the Bounceable interface. Any class type that implements this interface must agree
to write the code for the bounce() and setBounceFactor() methods.?

By defining an interface for Bounceable, any class that wants to be treated as a
Bounceable thing can simply implement the Bounceable interface and provide code
for the interface?s two methods.
Interfaces can be implemented by any class, from any inheritance tree. This lets
you take radically different classes and give them a common characteristic. For
example, you might want both a Ball and a Tire to have bounce behavior, but
Ball and Tire don?t share any inheritance relationship; Ball extends Toy while
Tire extends only java.lang.Object. But by making both Ball and Tire
implement Bounceable, you?re saying that Ball and Tire can be treated as, ?Things
that can bounce,? which in Java translates to ?Things on which you can invoke the
bounce() and setBounceFactor() methods.? Figure 2-8 illustrates the
relationship between interfaces and classes.
Think of an interface as a 100-percent abstract class. Like an abstract class, an
interface defines abstract methods that take the form,
abstract void bounce(); // Ends with a semicolon rather than curly braces
But while an abstract class can define both abstract and nonabstract methods,
an interface can have only abstract methods. Another place interfaces differ from abstract classes is that interfaces have very little flexibility in how the methods and
variables defined in the interface are declared. The rules are strict, but simple:
■ All interface methods are implicitly public and abstract.
■ Interface methods must not be static.
■ You do not need to actually type the public or abstract modifiers in
the method declaration, but the method is still always public and abstract.
■ All variables defined in an interface must be public, static, and final?in
other words, interfaces can declare only constants, not instance variables.
■ Because interface methods are abstract, they cannot be marked final,
native, strictfp, or synchronized.
■ An interface can extend one or more other interfaces.
■ An interface cannot extend anything but another interface.
■ An interface cannot implement another interface or class.
■ An interface must be declared with the keyword interface.
■ Interface types can be used polymorphically (see Chapter 5 for more details).

M

marcelomarquetiPJ 3 de jul. de 2006

Justamente estou perguntando por causa que li isto no livro e nao entendi para que serve esses dois métodos… .

valeu … .

E

ElisonPJ 4 de jul. de 2006

Cara, pelo q entendi, a interface Bounceable é usada apenas como um exemplo… seria literalmente “uma coisa q pula”, tendo assim um contrato com dois métodos: bounce() e setBounceFactor(), que obrigatóriamente vc deve implementar na primeira classe concreta q implementa essa interface…

espero ter ajudado…

S

SchuenemannPJ 4 de jul. de 2006

Sim, é isso mesmo. É só um exemplo do livro.
Ela não existe de verdade.

M

marcelomarquetiPJ 4 de jul. de 2006

valeu … entendi . .!!!
eu estava achando que isso era da API…rs…rs.r.

valeu !!

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