Flash / Flex / ActionScript/Statement/try catch

Catch Blocks Example

   <source lang="java">

package {

   import flash.display.Sprite;
   public class Main extends Sprite
   {
       public function Main()
       {
           try
           {
               var n:int = sumSomeNumbers();
               trace(n);
           } catch (e:UnrelatedError) {
               trace("something unrelated happened.");
           } catch (e:DispleasingNumberError) {
               trace("somewhere, a number is displeasing.");
           } catch (e:Error) {
               trace("something bad happened");
           }
       }
       protected function sumSomeNumbers():int
       {
           var sum:int = 0;
           for (var i:int = 0; i < 10; i++)
           {
               sum += someNumber();
           }
           return sum;
       }
       protected function someNumber():int
       {
           var n:int = Math.round(Math.random() * 10);
           if (n < 2)
           {
               throw new PatheticallySmallNumberError();
           }
           return n;
       }
   }

} class DispleasingNumberError extends Error {} class PatheticallySmallNumberError extends DispleasingNumberError {} class UnrelatedError extends Error {}

       </source>
   
  

Catching Errors Generated by Flash

   <source lang="java">

package{

 import flash.display.*;
 
 public class Main extends Sprite{
   public function Main(){
       var object:Object = "Definitely Not a Display Object";
       try
       {
           var displayObject:DisplayObject = DisplayObject(object);
       } catch (error:TypeError) {
           trace("Incompatible cast!");
           displayObject = new Sprite();
       }
       addChild(displayObject);
   }
 }

}

       </source>
   
  

Multiple throw statements and multiple catch statements

   <source lang="java">

package{

 import flash.display.Sprite;
 
 public class Main extends Sprite{
   public function Main(){

       var sUsername:String = "";
       var erToThrow:Error;
       try {
         if(sUsername == "") {
           throw new EmptyStringException();
       
         }
         if(sUsername == undefined) {
           throw new UndefinedException();
         }
       }
       catch (erObject:EmptyStringException) {
             // Code to handle error.
       }
       catch (erObject:UndefinedException) {
         // Code to handle error.
       }
   }
 }

}

       </source>
   
  

Using return in catch

   <source lang="java">

package{

 import flash.display.Sprite;
 
 public class Main extends Sprite{
   public function Main(){

changeFlow ( );

   }
   public function changeFlow (  ):void {
     try {
       throw new Error("Test error.");
     } catch (e:Error) {
       trace("Caught: " + e.message);
       return;
     } finally {
       trace("Finally executed.");
     }
     trace("Last line of function.");
   }
 }

}

       </source>
   
  

Using return in try, after throw

   <source lang="java">

package{

 import flash.display.Sprite;
 
 public class Main extends Sprite{
   public function Main(){
        changeFlow (  );
   }
   public function changeFlow (  ):void {
     try {
       throw new Error("Test error.");
       return;
     } catch (e:Error) {
       trace("Caught: " + e.message);
     } finally {
       trace("Finally executed.");
     }
     trace("Last line of method.");
   }
 }

}

       </source>
   
  

Working with Basic try/catch Statements

   <source lang="java">

/* try {

 // Code to try.

} catch (erObject:Error) {

 // Code to run if the try code throws an error.

}

• /

package{

 import flash.display.Sprite;
 
 public class Main extends Sprite{
   public function Main(){
       var sUsername:String = ""; 
       
       try { 
       
         if(sUsername == "") { 
           throw new Error();
         } 
         trace("The try block ran successfully."); 
       } catch (erObject:Error) { 
         trace("An error was thrown.");
       }
   }
 }

}

       </source>