Flash, AIR, ActionScript: File & FileStream

Cannot write to filesystem at File.applicationDirectory
But yet you can write using File.applicationDirectory.nativePath

To serialise an object of a custom class,
1) use flash.net.registerClassAlias( aliasName:String, classObject:Class)
to register the class before writing or reading
2) implement IExternalizable to your custom class
- readExternal(input:IDataInput):void
- writeExternal(output:IDataOutput):void
- Alternatively, you can use public fields in the custom class. But that is not entirely recommended for real world application.

import flash.filesystem.*;
import flash.net.*;

var a:A = new A();
...
...

function write():void{
  registerClassAlias("A", A);
  fileStream.open(file, FileMode.UPDATE);
  fileStream.writeObject(a);
  fileStream.close();
}
function read():void{
  fileStream.open(file, FileMode.READ);
  var o:A = fileStream.readObject() as A;
  o.c();
  fileStream.close();
}

/********************
   class A
********************/
import flash.utils.*;
 
public class A implements IExternalizable
{
  var b:int = 10;
  public function c():void{
   trace(b);
  }
  public function readExternal(input:IDataInput):void
  {
    b = input.readInt();
  }
  public function writeExternal(output:IDataOutput):void
  {
    output.writeInt(b);
  }
}