ACTIONSCRIPT 3 Developer’s Guide en

ACTIONSCRIPT 3.0 DEVELOPER’S GUIDE
Working with arrays
Arrays example: PlayList
Flash Player 9 and later, Adobe AIR 1.0 and later
The PlayList example demonstrates techniques for working with arrays, in the context of a music playlist application
that manages a list of songs. These techniques are:
Creating an indexed array
Adding items to an indexed array
Sorting an array of objects by different properties, using different sorting options
Converting an array to a character-delimited string
To get the application files for this sample, see www.adobe.com/go/learn_programmingAS3samples_flash. The
PlayList application files can be found in the Samples/PlayList folder. The application consists of the following files:
File Description
PlayList.mxml
or
PlayList.fla
PlayList class overview
Flash Player 9 and later, Adobe AIR 1.0 and later
The PlayList class manages a set of Song objects. It has public methods with functionality for adding a song to the
playlist (the addSong() method) and sorting the songs in the list (the sortList() method). In addition, the class
includes a read-only accessor property, songList, which provides access to the actual set of songs in the playlist.
Internally, the PlayList class keeps track of its songs using a private Array variable:
public class PlayList
{
private var _songs:Array;
private var _currentSort:SortProperty = null;
private var _needToSort:Boolean = false;
...
}
In addition to the _songs Array variable, which is used by the PlayList class to keep track of its list of songs, two other
private variables keep track of whether the list needs to be sorted (_needToSort) and which property the song list is
sorted by at a given time (_currentSort).
As with all objects, declaring an Array instance is only half the job of creating an Array. Before accessing an Array
instance’s properties or methods, it must be instantiated, which is done in the PlayList class’s constructor.
Last updated 6/6/2012
The main application file in Flash (FLA) or Flex (MXML).
com/example/programmingas3/playlist/PlayList.as A class representing a list of songs. It uses an Array to store the list,
and manages the sorting of the list’s items..
com/example/programmingas3/playlist/Song.as A value object representing information about a single song. The
items that are managed by the PlayList class are Song instances.
com/example/programmingas3/playlist/SortProperty.as A pseudo-enumeration whose available values represent the
properties of the Song class by which a list of Song objects can be
sorted.
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