Adobe FLEX 2-PROGRAMMING ACTIONSCRIPT 3.0 Manual page 128

The Flash Player API follows a convention in which interface names begin with an uppercase
, but you can use any legal identifier as an interface name. Interface definitions are often
I
placed at the top level of a package. Interface definitions cannot be placed inside a class
definition or inside another interface definition.
Interfaces can extend one or more other interfaces. For example, the following interface,
IExample, extends the IExternalizable interface:
public interface IExample extends IExternalizable
{
function extra():void;
}
Any class that implements the IExample interface must include implementations not only for
the method, but also for the
extra()
inherited from the IExternalizable interface.
Implementing an interface in a class
A class is the only ActionScript 3.0 language element that can implement an interface. Use the
keyword in a class declaration to implement one or more interfaces. The
implements
following example defines two interfaces, IAlpha and IBeta
implements them both:
interface IAlpha
{
function foo(str:String):String;
}
interface IBeta
{
function bar():void;
}
class Alpha implements IAlpha, IBeta
{
public function foo(param:String):String {}
public function bar():void {}
}
In a class that implements an interface, implemented methods must do the following:
Use the access control identifier.
public
■
Use the same name as the interface method.
■
Have the same number of parameters, each with data types that match the interface
■
method parameter data types.
Use the same return type.
■
128 Object-Oriented Programming in ActionScript
and
writeExternal() readExternal()
and a class, Alpha, that
,
methods