Combining array elements into a character-delimited string
In addition to using an array to maintain the song list in the PlayList class, in this example arrays are also used in the Song class to help manage the list of genres to which a given song belongs. Consider this snippet from the Song class’s definition: private var _genres:String; public function Song(title:String, artist:String, year:uint, filename:String, genres:Array)
{
...
// Genres are passed in as an array
// but stored as a semicolon-separated string.
this._genres = genres.join(";");
}
When creating a new Song instance, the genres parameter that is used to specify the genre
(or genres) the song belongs to is defined as an Array instance. This makes it convenient to group multiple genres together into a single variable that can be passed to the constructor.
However, internally the Song class maintains the genres in the private _genres variable as a semicolon-separated String instance. The Array parameter is converted into a semicolonseparated string by calling its join() method with the literal string value ";" as the specified delimiter.
By the same token, the genres accessors allow genres to be set or retrieved as an Array: public function get genres():Array
{
// Genres are stored as a semicolon-separated String,
// so they need to be transformed into an Array to pass them back out.
return this._genres.split(";");
} public function set genres(value:Array):void
{
// Genres are passed in as an array,
// but stored as a semicolon-separated string.
this._genres = value.join(";");
}
The genres set accessor behaves exactly the same as the constructor; it accepts an Array and calls the join() method to convert it to a semicolon-separated String. The get accessor performs the opposite operation: the _genres variable’s split() method is called, splitting the String into an array of values using the specified delimiter (the literal string value ";" as before).
Example: PlayList 253
