image path on mobile - AIR

I want to create image on my mobile application, after that i want to export the image. this is my code i got from other tutorial post. im using adobe flash and export it as AIR for android.

var jpgEncoder:JPGEncoder = new JPGEncoder(90);

var byteArray:ByteArray = jpgEncoder.encode( bitmapData );

// set an filename

var filename:String = "cool-wallpaper.jpg";

// get current path

var file:File = File.applicationDirectory.resolvePath( filename );

// get the native path

var wr:File = new File( file.nativePath );

// create filestream

var stream:FileStream = new FileStream();

//  open/create the file, set the filemode to write; because we are going to save

stream.open( wr , FileMode.WRITE);

// write your byteArray into the file.

stream.writeBytes ( byteArray, 0, byteArray.length );

// close the file. That’s it.

stream.close();

on my computer, the image appear on the same link as my source application. but its not working on mobile.

i tried this using android, my application is working but the image is not appear (i can't found it on any folder in my android phone).

i think i should change the path on: var filename:String = "cool-wallpaper.jpg";

but don't know what is the right path..

any one can help me about this image path issue?