Suppose you have a guest list for a party: You can store that information in ActionScript with variables like the following:

 name1 = "John Smith";  name2 = "Kelly McAvoy";  name3 = "Chris Taylor";  name4 = "Tripp Carter"; 

If Kelly tells you she can't make it to your party, besides being upset that only three people will be attending, you'll have to rename the variables beneath her name and shift them up your list. You can simplify this tedious task as well as many other similar data storage and manipulation chores by using arrays.

Think of arrays as supervariables: While a regular variable can only contain a single value, an array can contain multiple values which means you could store that entire guest list in a single array.

However, you must create an array in order to use it. Since arrays are objects, you use the Array object constructor method to create them. The syntax to create an array is as follows:

 myArray = new Array(); 

You can populate an array with values (separated by commas) when you create it, as in the following:

 guestList = new Array("John Smith","Kelly McAvoy","Chris Taylor","Tripp Carter"); 

Or you can use an alternative syntax:

 guestList = ["John Smith","Kelly McAvoy","Chris Taylor","Tripp Carter"]; 

Each value in an array is identified by an index number 0, 1, 2, and so on that denotes its position in the array. In the array we just created, "John Smith" has an index number of 0, "Kelly McAvoy" has an index number of 1, and so on. To access a value in an array, you would use the following syntax:

 myFavoriteGuest = guestList[1]; 

Here, the variable myFavoriteGuest is assigned a value of "Kelly McAvoy" because this is the value that exists at index position 1 in our guestList array.

The guestList array was created with four elements. You can add or modify elements at any time by referencing the specific element in the array. For instance, the following will update the value at index 2 from "Chris Taylor" to "Kris Tailor":

 guestList[2]="Kris Tailor"; 

An array element can contain any data type, including strings, numbers, and Boolean values, as well as entire objects. An array element can even contain another array. You'll learn more about arrays and methods of the Array object in later lessons. The following exercise in which you'll use arrays to store groups of related information for each day of the week represents just the beginning.

  1. With newsFlash2.fla still open, select Frame 1 of the Actions layer. Add the following ActionScript just below the"Monday, August 20 2001 variable set: = new Array();[0] = "rainy";[1] = "Very wet";[2] = 85;[3] = 62; 


    You have created an array called weather that's used to store weather data. The array is on the object monday. Remember: You'll store all information pertaining to Monday on the monday object.

    On the frames that contain graphics, you'll see a small weather icon (which currently displays the sun). This icon is a movie clip instance whose timeline contains three frame labels that hold weather icons that correspond to three different weather conditions. The frame labels are sunny, rainy, and stormy. The value of the first element (the 0th index) of the weather array will later be used to send this movie clip instance to the correct frame. Here it's set to "rainy" because Monday is supposed to be rainy. The second element of the weather array contains a blurb about Monday's weather, which will later be displayed on the screen.


    The high and low temperatures for Monday are stored in the third and fourth elements of the weather array, respectively. These values will be accessed later so that they can be displayed on the news page.

    You have just created an array that stores four pieces of related information in an easily accessible way.

  2. With Frame 1 still selected, insert the following ActionScript after"Tuesday, August 21 2001", : = new Array();[0] = "sunny";[1] = "Beautiful Day!";[2] = 90;[3] = 73; 

    Here we have created another array named weather , only this array is on the tuesday object. It contains weather information pertaining to Tuesday. The first element of this array now contains the value "sunny" so that the weather icon movie clip instance will display a sun. The value of each array element here is different from that of the weather array for Monday, but the index numbers of corresponding values are the same: Although the high temperatures for Monday and Tuesday differ, they're both stored at the Number 2 index position in each array.

    Now that you've created and structured your weather data, it's time to create and structure some news stories.

  3. Create arrays to contain news articles for individual categories by entering the following ActionScript just below[3]=62 :

     monday.entertainment = new Array();  monday.entertainment[0] = "MTV is 20!";  monday.entertainment[1] = "The popular TV network MTV has now been on the  air for 20 years…";  monday.entertainment[2] = "Jobe Makar";  monday.politics = new Array();  monday.politics[0] = "Jesse Ventura Wins";  monday.politics[1] = "Former WWF wrestler Jesse Ventura is elected governor  of Minnesota…";  monday.politics[2] = "Happy Camper";  monday.sports = new Array();  monday.sports[0] = "Head Tennis";  monday.sports[1] = "The Head Atlantis tennis racquet is one of the most  popular racquets in history…";  monday.sports[2] = "Jane Doe"; = new Array();[0] = "BajillaHertz Processors!";[1] = "The bajillaHertz processor has just hit the shelves  and is faster than light…";[2] = "John Doe"; 

    This news site can display four sections of stories: Entertainment, Politics, Sports, and Technology (as denoted by the navigation buttons on the left of the screen). For each of these sections, we've created an array and stored information about one article for that Monday. In the first section of this step, we created an array called entertainment . The first element of the entertainment array stores the news story's headline; the second element contains the actual news article; and the third element stores the name of the author. The politics , sports , and technology arrays contain the same type of information (headline, story, and author) at the same index positions.

    Although this information will be accessed on a later frame, by building a logical object-oriented storage structure for it now, you ensure that it will be easy to access when needed.

  4. Add this news article ActionScript just after[3]=73 :

     tuesday.entertainment = new Array();  tuesday.entertainment[0] = "Amazing Sci-Fi";  tuesday.entertainment[1] = "Sentrillion Blazers is the must see sci-fi movie  of the year!…";  tuesday.entertainment[2] = "Jobe Makar";  tuesday.politics = new Array();  tuesday.politics[0] = "Tax Refund";  tuesday.politics[1] = "Bush issues large tax refund…";  tuesday.politics[2] = "John Doe";  tuesday.sports = new Array();  tuesday.sports[0] = "Ryder Cup Begins";  tuesday.sports[1] = "The European golf tournament you have been waiting for  has just begun…";  tuesday.sports[2] = "Jane Doe"; = new Array();[0] = "KatrillaHertz Processor";[1] = "The katrillahertz processor just out and is twice  as fast as the bajillahertz chip…";[2] = "John Doe"; 

    This ActionScript stores the headlines, stories, and authors for the four news sections on Tuesday. The array names are the same as they were for Monday; the only difference is the information stored. Tuesday's information structure is exactly the same as that for Monday.

  5. Save your work as newsFlash3.fla.

    You have now created the information storage structure for your news site. Because all of the script we've discussed thus far is placed on Frame 1, this data is created as soon as the movie begins to play. Next, you must add the capability to retrieve the information and display it on screen.

Macromedia Flash MX ActionScripting Advanced. Training from the Source
Macromedia Flash MX ActionScripting: Advanced Training from the Source
ISBN: 0201770229
EAN: 2147483647
Year: 2002
Pages: 161 © 2008-2017.
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