Flash CS3 Documentation

Programming ActionScript 3.0 > Getting started with ActionScript > Creating your own classes > Writing the code for a class

Writing the code for a class

Once you have a design plan for your class, or at least some idea of what information it will need to keep track of and what actions it will need to carry out, the actual syntax of writing a class is fairly straightforward.

Here are the minimum steps to create your own ActionScript class:

1. Open a new text document, in an ActionScript-specific program such as Flex Builder or Flash, in a general programming tool such as Dreamweaver, or in any program that allows you to work with plain text documents.
2. Enter a class statement to define the name of the class. To do this, enter the words public class, and then the class's name, followed by opening and closing curly braces that will surround the contents of the class (the method and property definitions). For example:

   public class MyClass
   {
   }
   

   The word public indicates that the class can be accessed from any other code. For other alternatives, see Access control namespace attributes.

3. Type a package statement to indicate the name of the package in which your class will be found. The syntax is the word package, followed by the full package name, followed by opening and closing curly braces (which will surround the class statement block). For example, we'd change the code in the previous step to this:

   package mypackage 
   { 
       public class MyClass
       {
       }
   }
   

4. Define each property in the class using the var statement within the class body; the syntax is the same as you use to declare any variable (with the addition of the public modifier). For example, adding these lines between the opening and closing curly braces of the class definition will create properties named textVariable, numericVariable, and dateVariable:

   public var textVariable:String = "some default value";
   public var numericVariable:Number = 17;
   public var dateVariable:Date;
   

5. Define each method in the class using the same syntax that's used to define a function. For example:
   • To create a myMethod() method, enter:

     public function myMethod(param1:String, param2:Number):void
     {
         // do something with parameters
     

     }

     
     
   • To create a constructor (the special method that is called as part of the process of creating an instance of a class), create a method whose name matches exactly the name of the class:

     public function MyClass()
     {
         // do stuff to set initial values for properties
         // and otherwise set up the object
         textVariable = "Hello there!";
         dateVariable = new Date(2001, 5, 11);
     

     }

     
     

     If you don't include a constructor method in your class, the compiler will automatically create an empty constructor (one with no parameters and no statements) in your class.

There are a few more class elements that you can define.These elements are more involved.

• Accessors are a special cross between a method and a property. When you write the code to define the class, you write the accessor like a method so you can perform multiple actions (rather than just reading or assigning a value, which is all you can do when you define a property). However, when you create an instance of your class, you treat the accessor like a property--using just the name to read or assign the value. For more information, see Get and set accessor methods.
• Events in ActionScript aren't defined using a specific syntax. Instead, you define events in your class by using the functionality of the EventDispatcher class to keep track of event listeners and notify them of events. For more on creating events in your own classes, see Handling events.

Flash CS3

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philggg said on Apr 22, 2007 at 2:09 PM :

What is the relationships between:
.as files
packages
classes

Can there be more than one class in a package?

djtechwriter said on Apr 23, 2007 at 2:39 PM :

Only one class per package, but you can add classes within the same file outside the package declaration. For more details see this section:
http://livedocs.adobe.com/flash/9.0/main/00000041.html

LPCpatrick said on May 31, 2007 at 1:10 PM :

Having issues with calling private methods from event listerners inside custom classes. Is there something I am missing or any documentation on this?

ex.

package {
// imports
class MyExample extends Sprite {
// propreties and constructor....
xmlLoader.addEventListener(Event.COMPLETE, myXMLHandler)

private function myXMLHandler(evt:Event):void{
// dostuff to XML doc and call other function....
myOtherFunction()
}
private function myOtherFunction():void{
// do something with some propreties
}
}
}

results in : 1009 error.

thanks

No screen name said on Dec 1, 2007 at 1:42 PM :

I think you need to add "this." in your eventlistener to make it work.

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