interface

Availability

Flash Player 6.

Usage

interface InterfaceName {}
interface InterfaceName [extends InterfaceName [, InterfaceName ...] {}

Note: To use this keyword, you must specify ActionScript 2.0 and Flash Player 6 or later in the Flash tab of your FLA file's Publish Settings dialog box. This keyword is supported only when used in external script files, not in scripts written in the Actions panel.

Description

Keyword; defines an interface. An interface is similar to a class, with the following important differences:

• Interfaces contain only declarations of methods, not their implementation. That is, every class that implements an interface must provide an implementation for each method declared in the interface.
• Only public members are allowed in an interface definition. In addition, instance and class members are not permitted.
• The get and set statements are not allowed in interface definitions.

For more information, see Creating and using interfaces.

Example

The following example shows several ways to define and implement interfaces.

(in top-level package .as files Ia, B, C, Ib, D, Ic, E)

// filename Ia.as
interface Ia
{
  function k():Number;         // method declaration only
  function n(x:Number):Number; // without implementation 
}
// filename B.as
class B implements Ia
{
  function k():Number {return 25;}
  function n(x:Number):Number {return x+5;}
} 
// external script or Actions panel
mvar = new B();
trace(B.k());   // 25
trace(B.n(7)); // 12

// filename c.as
class C implements Ia 
{
  function k():Number {return 25;}
} // error: class must implement all interface methods

// filename Ib.as
interface Ib
{
  function o():Void;
} 
class D implements Ia, Ib
{
  function k():Number {return 15;}
  function n(x:Number):Number {return x*x;}
  function o():Void {trace("o");} 
} 

// external script or Actions panel
mvar = new D();
trace(D.k());   // 15
trace(D.n(7));  // 49
trace(D.o());   // "o"

interface Ic extends Ia
{
  function p():Void;
} 
class E implements Ib, Ic
{
  function k():Number {return 25;}
  function n(x:Number):Number {return x+5;}
  function o():Void {trace("o");} 
  function p():Void {trace("p");} 
} 

See also

class, extends, implements