Adobe FLEX 2-MIGRATING APPLICATIONS TO FLEX 2 User manual

Migrating Applications to Flex 2
Adobe®Flex™2

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Migrating Applications to Flex™ 2
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3
Contents
About Flex Documentation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7
Using this manual . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7
Accessing the Flex documentation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7
Chapter 1: Getting Started . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9
Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .9
Step 1: Find and replace . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10
Step 2: Add access modifiers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14
Step 3: Add types. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15
Step 4: Update events. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16
Step 5: Import classes for package-level functions . . . . . . . . . . . . . . . . 17
Step 6: Put all ActionScript components in packages. . . . . . . . . . . . . . 17
Step 7: Update data services. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18
Step 8: Charts . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18
Step 9: Overrides . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18
Step 10: Binding . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19
Step 11: API updates . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19
Chapter 2: ActionScript 2.0 to 3.0. . . . . . . . . . . . . . . . . . . . . . . . . 21
Overview. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21
Usability improvements. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22
Classes and packages. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25
Using external files . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 28
Initializing variables . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29
Typing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 32
Global functions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 34
Miscellaneous . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 36
Chapter 3: Flex Classes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 41
Core classes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 42
Containers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 53
Controls . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 61
Effects. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 81

4Contents
Events . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 84
Formatters. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 89
Interfaces. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .90
Managers. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 91
Media controls . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 94
Printing. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 94
Resources . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 95
Service tags . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 95
Skins. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 97
States . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 98
Utilities . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 99
Validators . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 99
Chapter 4: Data Providers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 101
Chapter 5: Binding . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 105
About binding . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 105
The <mx:Binding> tag must be a top-level tag . . . . . . . . . . . . . . . . . . . . 106
Binding from a property . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 106
Binding with Arrays . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .110
Chapter 6: Events . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 111
About events. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .112
Component startup life cycle . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .112
Migrating the Event object . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .113
Using static constants . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .114
Using function listeners . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .115
Using the EventDispatcher class . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .116
Maintaining scope . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 117
Using setCapture() . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 117
Keyboard events . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 117
Chapter 7: Styles and Skinning. . . . . . . . . . . . . . . . . . . . . . . . . . . 119
Using styles. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .119
Using skinning . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 124
Using embedded fonts . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 126
Themes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 127
Chapter 8: Behaviors . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 129
Overview . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 130
New Behaviors syntax . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .131

Contents 5
Chapter 9: Data Services. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 135
About Data Services . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .135
Migrating RemoteObject components . . . . . . . . . . . . . . . . . . . . . . . . . . 137
Migrating HTTPService components . . . . . . . . . . . . . . . . . . . . . . . . . . .140
Migrating WebService components . . . . . . . . . . . . . . . . . . . . . . . . . . . .143
Migrating secure data services . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .145
Mapping Java types for RemoteObject. . . . . . . . . . . . . . . . . . . . . . . . . .150
Accessing request/response data with RemoteObject . . . . . . . . . . . .152
Chapter 10: Configuration and Command Line Tools. . . . . . . . . 153
Configuration files. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .154
Security. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .155
Command-line compilers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .156
fdb debugger . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .158
Chapter 11: Customizing Components . . . . . . . . . . . . . . . . . . . . . 161
UIObject class removed . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 161
Class variables changed . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 161
Specifying the package. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .162
Defining the class . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .162
Defining the constructor . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .162
Creating bindable properties . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .162
Overriding a method . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .163
Clip parameters removed . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .163
Initialization sequence changed . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .163
Renamed invalidateStyle() . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .163
Chapter 12: Additional Migration Issues. . . . . . . . . . . . . . . . . . . . 165
HistoryManager . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .165
Charting . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .165
Cell renderers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .169
Validators . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 170
Embedding resources . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 172
Chapter 13: Migration Patterns . . . . . . . . . . . . . . . . . . . . . . . . . . . 173
Instantiating Flex controls. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 174
Using mixins. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 175
Variable enumeration and object introspection . . . . . . . . . . . . . . . . . . . 176
Using the drag-and-drop feature . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 178
Using Timer . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .182
Using the Preloader . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .183
Accessing request data. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .183

6Contents

7
About Flex Documentation
Migrating Applications to Flex 2 provides information on updating applications written for
Flex 1.x to Flex 2.
Contents
Using this manual . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7
Accessing the Flex documentation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7
Using this manual
This manual can help anyone who has developed Flex applications. You should have an
understanding of the architecture and details of the Flex 1.x framework.
Adobe recommends that you begin with Chapter 1, “Getting Started,” on page 9. This topic
provides several steps that are meant to walk you through performing a large majority of the
simple tasks in migration your applications.
You should then examine each of the other topics that provides more in-depth information
about changes to particular areas of Adobe® Flex™ 2, including events, effects, and data
binding.
Finally, for more complex migration issues, you should examine Chapter 13, “Migration
Patterns,” on page 173. This topic provides longer examples that provide context to certain
difficult migration issues.
Accessing the Flex documentation
The Flex documentation is designed to provide support for the complete spectrum of
participants.

8AboutFlexDocumentation
Documentation set
The Flex documentation set includes the following titles:
Viewing online documentation
All Flex documentation is available online in Adobe® Acrobat® Portable Document Format
(PDF) files from the Adobe website.
Typographical conventions
The following typographical conventions are used in this book:
■Italic font indicates a value that should be replaced (for example, in a folder path).
■Code font indicates code.
■Code font italic indicates a parameter.
■Boldface font indicates a verbatim entry.
Book Description
Flex 2 Developer’s Guide Describes how to develop your dynamic web
applications.
Getting Started with Flex 2 Contains an overview of Flex features and
application development procedures.
Creating and Extending Flex 2
Components
Describes how to create and extend Flex
components.
Migrating Applications to Flex 2 Provides an overview of the migration process, as
well as detailed descriptions of changes in Flex and
ActionScript.
Using Flex Builder 2 Contains comprehensive information about all
Adobe® Flex™ Builder™ 2 features, for every level of
Flex Builder users.
Adobe Flex 2 Language Reference Provides descriptions, syntax, usage, and code
examples for the Flex API.

9
1
CHAPTER 1
Getting Started
This topic describes the first steps of migrating a Macromedia Flex 1.x application to Adobe
Flex 2. This topic describes steps that are meant to be accomplished quickly and resolve most
of the warnings and errors that you encounter. When you complete the steps in this topic, you
should read other topics in this manual for more information about specific migration
operations.
Contents
Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9
Step 1: Find and replace . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10
Step 2: Add access modifiers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14
Step 3: Add types. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15
Step 4: Update events. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16
Step 5: Import classes for package-level functions . . . . . . . . . . . . . . . . . . . . . . . . . . . .17
Step 6: Put all ActionScript components in packages. . . . . . . . . . . . . . . . . . . . . . . . . .17
Step 7: Update data services. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18
Step 8: Charts . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18
Step 9: Overrides . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18
Step 10: Binding . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19
Step 11: API updates . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19
Introduction
You should undertake the migration process in a series of steps. The earlier steps involve
simple tasks, such as finding and replacing, or adding access modifiers. This topic describes
these steps. The later steps are more involved and require you to read other topics in this
manual. For example, when you convert portions of an application that uses binding, you
should read Chapter 5, “Binding,” on page 105.

10 Getting Started
The basic steps are the following:
■“Step 1: Find and replace” on page 10
■“Step 2: Add access modifiers” on page 14
■“Step 3: Add types” on page 15
■“Step 4: Update events” on page 16
■“Step 6: Put all ActionScript components in packages” on page 17
■“Step 7: Update data services” on page 18
■“Step 8: Charts” on page 18
■“Step 9: Overrides” on page 18
■“Step 10: Binding” on page 19
■“Step 11: API updates” on page 19
The remaining sections of this topic describe these steps in detail.
Step 1: Find and replace
There are many simple operations that you can do to your application to minimize the
number of warnings and errors you get when you first attempt to compile your application. In
many cases, these operations require that you do a find and replace.
You should not have to spend much time performing these tasks because the differences
between the Flex 1.x and Flex 2 syntax is generally minor but necessary. These operations
include the following:
■“Application namespace” on page 11
■“Void” on page 11
■“Newline” on page 11
■“Effects/behaviors” on page 14
■“Application and container initialization” on page 12
■“Alpha and scale properties” on page 12
■“Event.currentTarget” on page 12
■“Uninitialized values” on page 12
■“Replace _root” on page 13
■“Application namespace” on page 11
■“Effects/behaviors” on page 14
■“getURL() method” on page 14

Step 1: Find and replace 11
This section describes only the most common targets of finding and replacing. There are
many other members of Flex classes that have changed that are not mentioned here. For a
complete list, see Chapter 3, “Flex Classes,” on page 41.
Application namespace
Change the MXML namespace. Change the following:
xmlns:mx="http://www.macromedia.com/2003/mxml"
to this:
xmlns:mx="http://www.adobe.com/2006/mxml"
For example:
<mx:Application xmlns:mx="http://www.adobe.com/2006/mxml">
Void
Replace Void (with a capital V) with void (with a lower-case v).
Newline
The newline constant has been removed. In ActionScript, use “\n” to add a carriage return in
your Strings. In an MXML tag, use the &#13; XML character entity to add a carriage return.
Color value formats
Replace all occurrences of 0x with # in CSS style sheets or <mx:Style> tag blocks. The
supported color value formats have changed; for example:
.b1 { color: red; } // Valid
.b2 { color: #FF0000; } // Valid
.b3 { color: 0xFF0000; } // Invalid
In calls to the setStyle() method, you can prefix RRGGBB color values with 0x or #, but
you must put quotation marks around constants and # values; for example:
b1.setStyle("color",0xFF0000); // Valid
b2.setStyle("color","red"); // Valid
b3.setStyle("color","#FF0000"); // Valid
b4.setStyle("color",red); // Invalid
b5.setStyle("color",#FF0000); // Invalid
For more information on changes to the supported color value formats, see “Using colors”
on page 121.

12 Getting Started
Application and container initialization
The initialize event is now dispatched later in the startup and component creation life
cycle. In particular, it is now dispatched after the object’s children have been created. If your
event handler assumes that the object’s children have already been created, you can use the
initialize event. If your event handler requires that the object’s children have been
processed by the LayoutManager class, use the creationComplete event; for example:
<mx:Application xmlns:mx="http://www.adobe.com/2006/mxml"
creationComplete="initApp()">
Alpha and scale properties
The scaleX, scaleY, and alpha properties now range from 0.0 to 1.0, rather than 1 to 100.
This is also true for the Fade.alphaFrom, Fade.alphaTo, Zoom.zoomFrom, and
Zoom.zoomTo properties.
Event.currentTarget
Use the currentTarget property rather than the target property of the Event object. The
Event object now has two properties: target and currentTarget. The former is the object
that originally dispatched the event, and the latter is the object to which your event handler is
attached. The two are often the same, but they may differ if the event has bubbled up from a
child object.
In most cases, you will want to change the target property to the currentTarget property,
because the object that was previously the target is now most likely the current target; for
example:
switch (event.currentTarget.className) { ... }
For more information, see “Using the target property” on page 113.
Uninitialized values
Remove checks against the undefined value. In Flex 2, undefined is only for use with the *
(no-type) “type”. Other types can no longer store the undefined value. If you assign
undefined to other types, it will be coerced into null, NaN, 0, or false. You can use the
isNaN() method to check if a variable is NaN.
If you do not initialize a variable at all, the initial value is different than in Flex 1.x. For more
information, see “Initializing variables” on page 29.

Step 1: Find and replace 13
Replace _root
Remove the use of “_root” from your application code if you used it to access the Application
instance. In Flex 1.x, you could use _root to refer to the main application from anywhere in
your application or one of the components. This was never a recommended practice, but was
a convenient way to access the application root. To access the Application instance from
anywhere in your application, use Application.application.
import mx.core.Application;
function myFunction():void {
//_root.ta1.text = "Thank you!"; // Flex 1.x
Application.application.ta1.text = "Thank you!"; // Flex 2
}
Also, “_global” and “_level0” no longer exist.
Alerts
The Application.alert() convenience method was removed. You must now use the
mx.controls.Alert.show() method. You import the mx.controls.Alert class and call the
Alert.show() method, as the following example shows:
import mx.controls.Alert;
public function myEventHandler(event:Event):void {
Alert.show("An event occurred!");
}
If you call the show() method in an MXML tag, then you must also include a script block
that imports the mx.controls.Alert class, as the following example shows:
<?xml version="1.0"?>
<mx:Application xmlns:mx="http://www.adobe.com/2006/mxml">
<mx:Script><![CDATA[
import mx.controls.Alert;
]]></mx:Script>
<mx:Button id="b1" label="Show Style" click="Alert.show('Alert!');"/>
</mx:Application>

14 Getting Started
Effects/behaviors
For each effect, such as Fade, Sequence, and Parallel, change the name property to id. Also,
remove the <mx:Effect> tags; for example:
<mx:Sequence id="myWipes">
<mx:WipeLeft/>
<mx:WipeRight/>
<mx:WipeUp/>
<mx:WipeDown/>
</mx:Sequence>
For more information, see Chapter 8, “Behaviors,” on page 129.
getURL() method
Replace the getURL() method with the navigateToURL() method in the flash.net package.
This global method takes a URLRequest object; for example:
var url:URLRequest = new URLRequest("http://mysite.com");
navigateToURL(url,"_self");
For more information, see Chapter 34, “Communicating with the Wrapper,” in Flex 2
Developer’s Guide.
Step 2: Add access modifiers
You must add access modifiers to all your properties, variables, methods, and classes. Available
access modifiers are public, internal, private, or protected.
When you first write or port an application, it is easiest to set every method and property to
public. You can then revisit the application when it is working and begin restricting access by
adding the private identifier where necessary.
The following table shows some common situations where you add modifiers:
Flex 1.x Flex 2
function processVariables() {
// Returns a Boolean
}
public function processVariables():Boolean {
// Returns a Boolean
}
function getBalance() { ... } private function getBalance():Number { ... }
var s = "My name is Fred."; private var s:String = "My name is Fred.";
class MyButton extends Button { ... } public class MyButton extends Button { ... }

Step 3: Add types 15
The default access modifier for methods, variables, and classes is internal. This means that
all classes in the same package can access them, but classes outside of the package cannot.
However, the Flex compiler issues a warning if you do not specify any access modifier.
For more information about access modifiers, see “Access modifiers” on page 27. For
information about disabling warnings, see Chapter 9, “Using the Flex Compilers,” in Building
and Deploying Flex 2 Applications.
Step 3: Add types
All variables, properties, method arguments, and method return types should now be typed.
To find variables and properties, search for the keyword “var” to locate places where you
should type variables and properties.
The following table shows common variable typing tasks:
To find methods and method arguments, search for the keyword function and add a return
type if that method returns a value and type each method argument; for example:
Flex 1.x:
function getAnswer(myString) {
...
return myString;
}
Flex 2:
public function getAnswer(myString:String):String {
...
return myString;
}
For more information, see “Explicit typing” on page 32.
Flex 1.x Flex 2
var s = "Title Page"; public var s:String = "Title Page";
var myType = event.type; public var myType:String =
String(event.type);
item = event.target.selectedItem; item =
ThumbnailView(event.target.selectedItem);
public function
myHandler(event):void
public function myHandler(event:Event):void

16 Getting Started
Step 4: Update events
The Event model changed in Flex 2. However, you can migrate most event handlers with
minimal effort. This section describes the most popular changes that you must make to your
event handling code. For more information about migrating events, see Chapter 6, “Events,”
on page 111.
Specify types
Events are now more strongly typed than in Flex 1.x. As a result, you should specify the object
type in the event listener function. For example, previously you could write the following:
function myListener(event) { var s = event.type; }
Now, you must specify an event object in the function’s signature; for example:
private function myListener(event:Event):void { var s = event.type; }
Where possible, make the events as specific as possible. If the previous example was a listener
for click events, specify a MouseEvent as the type:
private function myListener(event:MouseEvent):void { ... }
Dispatch custom events
When you dispatch custom events, you must declare a new Event object rather than use a
generic object; for example:
click="dispatchEvent(new Event('checkOut'))"
Remove delegates
You are no longer required to wrap a listener function with a Delegate to maintain application
scope. You can remove the Delegate from the following line:
b1.addEventListener("click", mx.utils.Delegate.create(this,myListener));
So the line appears as follows:
b1.addEventListener(MouseEvent.CLICK, myListener);

Step 6: Put all ActionScript components in packages 17
Step 5: Import classes for package-level
functions
When you use package-level functions, you must import the package. For example, in Flex 1.x
you could call the show() method in the following way:
mx.controls.Alert.show("This is an Alert!");
In Flex 2, you must import the package before calling the function, as the following example
shows:
import mx.controls.Alert;
Alert.show("This is an Alert!");
Step 6: Put all ActionScript components
in packages
You must wrap all ActionScript components in a package statement, even if the component
is located in the same directory as the main application. If the component is in the same
directory as the main application, you can use an unnamed package, but the package
statement must be the first line of the component’s file; for example:
package {
public class MyClass {
// Class definition
}
} // Close package
Adobe recommends that you use unique package names so that there are no duplicate class
names in your source paths. The generally accepted syntax is to use the reverse URL
technique; for example:
com.yourcompany.MyPackage
Package names must match the directory hierarchy. For example, if you have the following
component used by your main application:
/myfiles/MainApp.mxml
/myfiles/mycomponents/TrivialComponent.mxml
Your package name must be mycomponents, as the following example shows:
package mycomponents {
...
}
For more information about the package statement syntax, see “Package statement syntax”
on page 26.

18 Getting Started
Step 7: Update data services
The RemoteObject, HTTPService, and WebService MXML services are now known as RPC
services. The RemoteObject tag is not functional unless you use Adobe Flex Data Services.
You must replace use of this with another tag.
You can still use the HTTPService and WebService tags, but you can only access resources on
a server that is in the same domain as the Flex application or from a server that has a
crossdomain.xml file installed on it. This file must allow access to the requesting application’s
domain. In addition, you must set useProxy=false in the MXML tag (the default).
For more information on using data services, see Chapter 9, “Data Services,” on page 135.
Step 8: Charts
If you are using Adobe Flex 2 SDK, you must now install a separate SWC file to use charts.
For more information, see the installation instructions in the Adobe Flex Charting’
readme.txt file.
If you are using the Flex Data Services server, charts are included.
The way charts are implemented also changed significantly. For more information, see
“Charting” on page 165.
Step 9: Overrides
Whenever a method on a subclass overrides a similarly named method on a superclass, the
declaration of the subclass’s method must now be prefixed by override. For more
information, see “Overriding a method” on page 163.

Step 11: API updates 19
Step 10: Binding
To make a user-defined variable bindable, you must now explicitly identify it by adding the
[Bindable] metadata tag to the property; for example:
[Bindable]
public var catalog:Array;
In addition, the <mx:Binding> tag must be moved to the top level. The following example
compiled in Flex 1.5:
<mx:HBox>
<mx:Label id="myLabel"/>
<mx:Label id="my2ndLabel" text="hello"/>
<mx:Binding source="my2ndLabel.text" destination="myLabel.text"/>
</mx:HBox>
In Flex 2, you must move the tag to the top level, as the following example shows:
<mx:Binding source="my2ndLabel.text" destination="myLabel.text"/>
<mx:HBox>
<mx:Label id="myLabel"/>
<mx:Label id="my2ndLabel" text="hello"/>
</mx:HBox>
For more information, see Chapter 5, “Binding”.
Step 11: API updates
The Flex ActionScript API has been updated to be more user-friendly. Changes include
enforcing proper capitalization, making class and property names clearer and more intuitive,
eliminating redundant classes and properties, and unifying common properties across
controls.
The following specific areas changed:
■Event names. All event names and their constants were changed to present tense. For
example, the childAdded event is now childAdd, and its constant, CHILD_ADDED, is
now CHILD_ADD.
■Camel-casing. Package, method, and property names now consistently use camel-case. For
example, the mx.containers.accordionclasses package name is now
mx.containers.accordionClasses.
■Renderers. The terms cell, data, and row have been changed to item for renderers. For
example, cellFocusIn is now itemFocusIn, and the charting event mouseOverData is now
itemMouseOver.

20 Getting Started
■Expanded abbreviations. Abbreviations in property and method names have been
expanded where practical. For example, the hPosition property is now
horizontalPosition.
■Property names. Some properties have been renamed so that their function is more
evident. For example, the Boolean multipleSelection is now
allowMultipleSelection.
■Chart skins. The chart skins are now referred to as renderers.
■Unnecessary interfaces and classes. Unnecessary interfaces and classes have been removed
and their functionality has been moved to other interfaces and classes where necessary.
For a complete list of changes, see Chapter 3, “Flex Classes,” on page 41. This topic presents
these changes in tabular format.