Can't write to file in Android

Question

This following code snippet seems to create a file successfully, and the writeData function writes to the StringWriter appropriately, however the file seems to be empty..

fileOutputStream = new FileOutputStream(selectedFile);

if(!selectedFile.exists())
    selectedFile.createNewFile();


StringWriter writer = new StringWriter();
serializer.setOutput(writer);

Log.i(TAG, "- Output is asigned to the special Serializer object");     

/* The target data is written to the a string buffer in the StringWriter */
writeData(serializer, templateData); 

Log.i(TAG, String.format("- New file Data written: %s", writer.toString())); // Logcat prints the file data from this string beautifully..      

fileOutputStream.write(writer.toString().getBytes()); // Not happening?! Why :(
fileOutputStream.close();

The String is definately not empty!

The file created however, is empty! I've also tried variations with OuputStreamWriter and the like but the file is not written into. Why? I am testing this on a Nexus 7 tablet and I have the WRITE_EXTERNAL_STORAGE permission set.

Update: All the files are created in this process. The access permission of the file is created as "_rw".

Other methods I've used that give exactly the same result:

FileWriter fw = new FileWriter(selectedFile.getPath());
fw.write(writer.toString());
fw.flush();
fw.close();

In all cases, a file is created via createNewFile() however no data is ever written to it. The app carries on as normal without throwing anything. I just don't understand :'(

Ensure the file is created before creating an `OutputStream` on it. — Alex, Oct 17 '12 at 16:58
No the is flushed in the writeData function, and the appropriate data is written to the StringWriter — user965369, Oct 17 '12 at 17:09
@Alex I have tried it both ways it doesn't seem to make a difference. — user965369, Oct 17 '12 at 17:10
Is the file writeable by the userid of your process? Delete the target file and try again... — Keith Randall, Oct 17 '12 at 17:11
If the target file started off as empty and isn't writeable by your process for some reason (probably, owned by another user), then it wouldn't succeed. — Keith Randall, Oct 17 '12 at 17:13
No the all the files are explicitly created in this process! Ill update the question:) — user965369, Oct 17 '12 at 17:15

score 0 · Answer 1 · answered Oct 17 '12 at 17:14

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FileOutputStream fOut = openFileOutput(selectedFile);//u can use (filename, Context.MODE_APPEND | Context.MODE_WORLD_READABLE)

if(!selectedFile.exists())
    selectedFile.createNewFile();

OutputStreamWriter osw = new OutputStreamWriter(fOut);
      osw.append(templateData);
      osw.flush();
      osw.close();

answered Oct 17 '12 at 17:14

Sardor Dushamov

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I've also tried this method - doesn't seem to work either! This is so frustrating there must be something bigger going on here. – user965369 Oct 17 '12 at 17:18

score 0 · Answer 2 · edited May 23 '17 at 12:21

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If you're calling FileOutputStream.FileOutputStream(File) after you've written to the file all the data will be erased. Check out this thread: How to write data with FileOutputStream without losing old data?

edited May 23 '17 at 12:21

Community

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answered Oct 17 '12 at 21:30

user965369

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Can't write to file in Android

2 Answers2