AIR file basics

Adobe AIR 1.0 and later

For a quick explanation and code examples of working with the file system in AIR, see the following quick start articles on the Adobe Developer Connection:

Adobe AIR provides classes that you can use to access, create, and manage both files and folders. These classes, contained in the flash.filesystem package, are used as follows:

File classes



File object represents a path to a file or directory. You use a file object to create a pointer to a file or folder, initiating interaction with the file or folder.


The FileMode class defines string constants used in the fileMode parameter of the open() and openAsync() methods of the FileStream class. The fileMode parameter of these methods determines the capabilities available to the FileStream object once the file is opened, which include writing, reading, appending, and updating.


FileStream object is used to open files for reading and writing. Once you’ve created a File object that points to a new or existing file, you pass that pointer to the FileStream object so that you can open it and read or write data.

Some methods in the File class have both synchronous and asynchronous versions:

  • File.copyTo() and File.copyToAsync()

  • File.deleteDirectory() and File.deleteDirectoryAsync()

  • File.deleteFile() and File.deleteFileAsync()

  • File.getDirectoryListing() and File.getDirectoryListingAsync()

  • File.moveTo() and File.moveToAsync()

  • File.moveToTrash() and File.moveToTrashAsync()

Also, FileStream operations work synchronously or asynchronously depending on how the FileStream object opens the file: by calling the open() method or by calling the openAsync() method.

The asynchronous versions let you initiate processes that run in the background and dispatch events when complete (or when error events occur). Other code can execute while these asynchronous background processes are taking place. With asynchronous versions of the operations, you must set up event listener functions, using the addEventListener() method of the File or FileStream object that calls the function.

The synchronous versions let you write simpler code that does not rely on setting up event listeners. However, since other code cannot execute while a synchronous method is executing, important processes such as display object rendering and animation can be delayed.