Trying to create a file in Android: open failed: EROFS (Read-only file system)

android file file-io filesystems android-file
Drew picture Drew · Mar 29, 2013 · Viewed 110.9k times · Source

This line:

final FileOutputStream outputStream = new FileOutputStream(name);

results in a FileNotFoundException with the message being /2ozjfFQzwv: open failed: EROFS (Read-only file system) where "2ozjfFQzwv" is what I passed as the name of the file.

I have tried this with and without the WRITE_INTERNAL_STORAGE permission. How do I create this file for writing?

Alternatively, I just want to be able to give an image to a new activity, and it is too large to serialize it in an extra. Is there an easier way than writing it to a file then reading from it again? All the questions on here seem to be about writing to an SD card, which I don't want to do because many people don't have SD card slots.

Answer

CommonsWare picture CommonsWare · Mar 29, 2013

I have tried this with and without the WRITE_INTERNAL_STORAGE permission.

There is no WRITE_INTERNAL_STORAGE permission in Android.

How do I create this file for writing?

You don't, except perhaps on a rooted device, if your app is running with superuser privileges. You are trying to write to the root of internal storage, which apps do not have access to.

Please use the version of the FileOutputStream constructor that takes a File object. Create that File object based off of some location that you can write to, such as:

  • getFilesDir() (called on your Activity or other Context)
  • getExternalFilesDir() (called on your Activity or other Context)

The latter will require WRITE_EXTERNAL_STORAGE as a permission.

Is there an easier way than writing it to a file then reading from it again?

You can temporarily put it in a static data member.

because many people don't have SD card slots

"SD card slots" are irrelevant, by and large. 99% of Android device users will have external storage -- the exception will be 4+ year old devices where the user removed their SD card. Devices manufactured since mid-2010 have external storage as part of on-board flash, not as removable media.

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