Unable to write to file in android

Question

This is driving me insane because it should be working. I'm trying to write two string arraylist to a file. Keep in mind I'm writing to internal storage, so manifest permissions are not the issue here. Here is my code:

File cacheFile = new File(context.getFilesDir(), getChannelFile(s[0]) + ".cache"); if (!cacheFile.exists()) { try { FileWriter out = new FileWriter(cacheFile); for (int i = 0; i < titleArray.size(); i++) { Log.d(timesArray.get(i), titleArray.get(i)); out.write(timesArray.get(i) + "#" + titleArray.get(i)); out.write(System.getProperty("line.separator")); } out.close(); } catch (Exception e) { Log.e(Ids.TAG, e.getMessage()); } }

Logcat shows exactly what I want to write. But it doesn't write to the file. After this code is executed, my file is created but is 0 bytes. I'm at a loss because there are no exceptions caught and my Log.d shows everything is correct. What am I missing here?

Wait, you were right, I was putting the out.flush() right above the out.close() but after putting the out.flush() within the for loop, it worked. Thanks! — Grux
– Grux, Commented Jun 15, 2014 at 1:32
That's strange. It should've worked as out.flush(); out.close(); unless you are getting an exception. Try putting the two into the finally block. — PM 77-1
– PM 77-1, Commented Jun 15, 2014 at 1:35

user3008107 · Accepted Answer · 2014-06-15 10:40:45Z

The following code snippet works when executed from activity's onResume method. This is not the best place of course, but it's ok for testing.

 File cacheFile = new File(getFilesDir(), "test.cache"); List<String> titleArray = new ArrayList<String>(Arrays.asList("a", "b", "c")); if (!cacheFile.exists()) { try { FileWriter out = new FileWriter(cacheFile); for (int i = 0; i < titleArray.size(); i++) { out.write(titleArray.get(i)); out.write(System.getProperty("line.separator")); } out.close(); } catch (Exception e) { Log.e("Test", e.getMessage()); } }

My questions which can lead you to an answer:

From what context are you trying to write the file from? BroadcastReceiver? Try from Activity/Service.
Are you writing from a background thread or the main one (shouldn't make any imaginable difference)?
Are you sure you have enough space? How big is the list? Try writing a very simple file with several bytes and read it back to confirm it worked.
Have you tried on different devices and/or the emulator? Does the problem persists?
What is the Android version you are building for and testing on?

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