# Library FileSystem (AIR)

**URL:** <https://forum.kirupa.com/t/library-filesystem-air/285573>\
**Category:** flash\
**Created:** [April 2, 2009, 2:44pm UTC](https://forum.kirupa.com/t/library-filesystem-air/285573 "2009-04-02T14:44:24Z")\
**Posts on this page:** 1\
**Page:** 1

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**Author:** ![hexagon06](https://avatars.discourse-cdn.com/v4/letter/h/87869e/32.png) [@hexagon06](https://forum.kirupa.com/u/hexagon06)\
**Post date:** [April 2, 2009, 2:44pm UTC](https://forum.kirupa.com/t/library-filesystem-air/285573/1 "2009-04-02T14:44:24Z")

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Hey all,

I created a new Library project in Flex Builder 3. In a few of the mxml classes I wanted to put in this library I use the flash.filesystem.File class. For some reason I can’t use it in the classes in the Library project. The error says that the Ytpe is not found when compiled.

In another project, which is a Flex project (so no Library project) I can use the File class without any problems.

Can anyone explain to me why this works like this and/or explain how to use the filesystem in an other way? (I now use it to read/write files on my HD).