File exists and IS directory, but listFiles() returns null

java android file io file-permissions
Wilson picture Wilson · Dec 21, 2013 · Viewed 52.7k times · Source

The documentation for File.listFiles() suggests that null will ONLY be returned in the case that the file calling it is not a directory.

I have the following:

String dir = "/storage/emulated/0";
File f = new File(dir);
Log.v("Files",f.exists()+"");
Log.v("Files",f.isDirectory()+"");
Log.v("Files",f.listFiles()+"");

The log reads:

true
true
null

For some reason, listFiles() is returning null even though the File is recognized as a valid directory. I'm not super familiar with Android file hierarchy behavior, so I would guess the problem lies in there.

For reference, I'm debugging on my Moto X, and results are the same whether the phone is plugged in to my computer or not - so I don't think it has to do with mounting when plugged in.

Answer

BamsBamx picture BamsBamx · Mar 6, 2014

For those with this problem, add this to AndroidManifest.xml: 

<uses-permission android:name="android.permission.READ_EXTERNAL_STORAGE" />

Problem solved :D

EDIT: If this does not work just make sure if path is correct

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