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While porting some older Java code to the Android platform, I read that it was possible to place custom files in the “files” directory reserved for the application. Great, that’s exactly what I need since packaging data files with the application as resources did not make sense in this case. So how do you move your own files into this directory?

With the Android emulator running, in Eclipse open the DDMS perspective, then select the File Explorer tab. Expand the directory tree to: data/data/com.your.package. Ok so where’s the “files” directory? Good question. Other posts I read on this subject seemed to assume that it will just be there. However on my emulator the files directory is not there by default. So how are we supposed to create the files directory?

Here’s one way. In your code write a test file to the default location, meaning don’t prepend with a path. Doing this will create the files directory and will also write the test file there as well. One caveat, if you delete all of your emulator temp files, the files directory and it’s contents will also be destroyed.

Here’s some code to write a test file into the files directory:

 
try{
  // this forces the files directory to be created under the package name
  FileOutputStream fileOut = mcontext.openFileOutput("test.txt", Context.MODE_WORLD_WRITEABLE );
  fileOut.close();
}catch(Exception e){}

After executing the above code on your emulator, you should now see a directory named “files” at data/data/com.your.package/files. This code needs to import java.io.FileOutputStream and also uses a reference to the Context.

Pull and Push icons

Move files into your new files directory by clicking the Push Files icon in the upper right corner of the DDMS-File Explorer view. If you know of an easier way to create the files directory please let me know.