Deleting files created with FileOutputStream

Question

I'm developing for the Android platform.
My app creates a temp file with a simple call to:

FileOutputStream fos = openFileOutput("MY_TEMP.TXT", Mode);

It works fine because I can write to it and read it normally.

The problem is that when I exit from the app I want to delete this file. I used:

File f = new File(System.getProperty("user.dir"), "MY_TEMP.TXT");
f.delete()

But it always returns false and the file is not deleted.
I have tried:

File f = new File("MY_TEMP.TXT");
f.delete();

And it does not work either.

Perimorph

Answer 1

I checked on this posting and the best way to delete a file created from FileOutputStream is a simple call from the Context method deleteFile(TEMP_FILE) as simple as that.

Chiaki

That's correct! It is extremely simple! just calling deleteFile(TEMP_FILE); It goes directly to the folder assigned to the profile and it is portable according to the documentation. It works for my need. Wow I was totally on the wrong track! Anyway, thank you all you guys for pointing me in the correct direction. – Perimorph

Yeah, it's really fastest way to delete file created with FileOutputStream – Goodall

Answer 2

You can't delete an opened file. You need to close the stream before delete.

fos.close();
f.delete();

That said, I would rather use File#createTempFile() to let the underlying platform do the automatic cleanup work and to avoid potential portability trouble caused by using relative paths in File.

Larousse

From createTempFile's docs: "This method provides only part of a temporary-file facility. To arrange for a file created by this method to be deleted automatically, use the deleteOnExit() method." – Poco

R. Bemrose: A decent OS periodically cleanups the temp directory. – Larousse

@BalusC: It's a shame Windows isn't a decent OS. ;) And I can't speak for Android on how it would handle that. – Poco

Agree with R. Bemrose's deleteOnExit() method. It's been very useful in the past. – Antisepticize

Thank you all for your responses. I closed the FileOutputStream object as soon as I finish working with it and before trying to delete it. 1 thing that worries me with temp files is that I need to keep the information of the file at hand until the user decides to finish the activity process. This is tricky because I don't want to lose the file contents when a call is received or if the user presses the home or back buttons. If the activity is stopped i need to preserve the data because it is a sequential process. File must be deleted UNTIL the user clicks the finish button. – Perimorph

That could be on the same session or until tomorrow. The user can be pausing the process. Because these are small pieces of information there's no need to use a database and all its hurdle. It's simple enough to use a flat file. – Perimorph

Ah yes, if it's not a temporary file, then you should also not create it as a temporary file :) One other thing which worries me, is the problem solved? Just wondering since the answer isn't marked accepted and your second statement is a bit ambiguous (it can also be interpreted as if you already took care of closing). – Larousse

Oh, sorry for the confusion! I should have not called temp file. No the problem is not solved yet. I tried to explain the details of the process in the 2nd posting. Actually what it is happening is that I close the activity by clicking on the finish button (calling the delete for the file) and then finish the Activity. When I load the Activity again it brings back the contents of the file. – Perimorph

What would be a better approach for this kind of behavior? I thought simple flat files would be enough. – Perimorph

Answer 3

you need to close the file, before deleting it. use below code.

        FileOutputStream fos = openFileOutput("MY_TEMP.TXT",Mode);
        File f = new File(System.getProperty("user.dir"),"MY_TEMP.TXT");
        fos.close();
        File f = new File("MY_TEMP.TXT");
        f.delete();

Livvyy

Answer 4

Double-check, if the Stream is closed before you attempt to delete the file.

Graeme

Answer 5

You have some solid answers already, but I just want to mention File.deleteOnExit() which schedules a file for deletion when the VM exits.

--edit--

You still should close any streams connected to the file.

Flossi

I'm not saying it would. Just another way to delete files :) – Flossi