Android mkdirs() creates a zero byte file instead of a folder

Question 1

I found a workaround which solves this problem. Whenever I am deleting a file/directory, instead of using delete() directly, I rename the file/folder, and then delete() it. This weird workaround seems to remove the problem.

I got this idea by seeing this question's answers - Open failed EBUSY device or Resource busy

However, I'm not sure why this works, or what caused the problem in the first place.

In case anyone else is using Felix on Galaxy Nexus and encounters the same problem, just change the Felix source code as shown below:

org.apache.felix.framework.util.SecureAction.java:

public boolean deleteFile(File target)
{
    if (System.getSecurityManager() != null)
    {
        try
        {
            Actions actions = (Actions) m_actions.get();
            actions.set(Actions.DELETE_FILE_ACTION, target);
            return ((Boolean) AccessController.doPrivileged(actions, m_acc))
                .booleanValue();
        }
        catch (PrivilegedActionException ex)
        {
            throw (RuntimeException) ex.getException();
        }
    }
    else
    {
        // Solution: Rename before deleting
        // https://stackoverflow.com/questions/11539657/open-failed-ebusy-device-or-resource-busy

        File to = new File(target.getAbsolutePath() + System.currentTimeMillis());
        boolean renameStatus = target.renameTo(to);
        boolean deleteStatus = to.delete();
        boolean returnStatus = ( renameStatus && deleteStatus );

        // Debug SecureAction
        //boolean returnStatus = target.delete();
        Log.e ( "SecureAction" , "Deleting " + target + " delete(): " + returnStatus );
        return returnStatus;
    }
}

Question 2

please use instead of

   File cacheDir = new File( Environment.getExternalStorageDirectory().getAbsolutePath() + 
          "/OSGiComponents/admin/felix-cache/" );
      cacheDir.mkdirs();

to

  File cacheDir = 
new File( Environment.getExternalStorageDirectory().getAbsolutePath() + 
          "/OSGiComponents/admin/felix-cache" );
     cacheDir.mkdir();

Question 3

I suggest that you connect to the device using adb and use the command ls -l in the directory, to check what is operating system reporting about this 0 size file (permissions, etc.). This can eventually bring some light to the issue.

If you can't figure out a working solution, maybe you can make a workarround using the exec() to execute a mkdir directly.

You can use the cobe bellow to do it:

public static boolean execCmd(String command, ArrayList<String> results){
    Process process;
    try {
        process = Runtime.getRuntime().exec(new String [] {"sh", "-c", command});
    } catch (IOException e) {
        e.printStackTrace();
        return false;
    } 

    int result;
    try {
        result = process.waitFor();
    } catch (InterruptedException e1) {
        e1.printStackTrace();
        return false;
    }

    if(result != 0){ //error executing command
        Log.d("execCmd", "result code : " + result);
        String line; 
        BufferedReader bufferedReader = new BufferedReader(new InputStreamReader(process.getErrorStream())); 
        try {
            while ((line = bufferedReader.readLine()) != null){
                if(results != null) results.add(line);
                Log.d("execCmd", "Error: " + line);
            }
        } catch (IOException e) {
            e.printStackTrace();
            return false;
        }
        return false;
    }

    //Command execution is OK
    BufferedReader bufferedReader = new BufferedReader(new InputStreamReader(process.getInputStream())); 

    String line; 
    try {
        while ((line = bufferedReader.readLine()) != null){
            if(results != null) results.add(line);
            Log.d("execCmd", line);
        }
    } catch (IOException e) {
        e.printStackTrace();
        return false;
    }
    return true;
}

To use it:

boolean res= execCmd("mkdir "+ Environment.getExternalStorageDirectory().getAbsolutePath() + "/OSGiComponents", results);
if(!res) return error;   

res= execCmd("mkdir "+ Environment.getExternalStorageDirectory().getAbsolutePath() + "/OSGiComponents/admin", results);
if(!res) return error;   

res= execCmd("mkdir "+ Environment.getExternalStorageDirectory().getAbsolutePath() + "/OSGiComponents/admin/felix-cache", results);
if(!res) return error;

Regards.

Question 4

String root = Environment.getExternalStorageDirectory()
            .getAbsolutePath()+"/OSGiComponents/admin/felix-cache";
    File myDir = new File(root);

    String fname = "Image Name as you want";
    File file = new File(myDir, fname);
    if (file.exists())
        file.delete();
    try {
        FileOutputStream out = new FileOutputStream(file);
        bitmap.compress(Bitmap.CompressFormat.PNG, 90, out);
        out.flush();
        out.close();

    } catch (Exception e) {
        e.printStackTrace();
    }

Question 5

Although not a direct answer to your question,the information mentioned below may help you:

In certain devices, the Environment.getExternalStorageDirectory().getAbsolutePath() does not necessary reflect the actual external sd card path. Sometimes it represents the internal storage.

for example in Galaxy Note 2:

Log.i(TAG,Environment.getExternalStorageDirectory().getAbsolutePath());

will print

12-19 17:35:11.366: E/sample.Examples(10420): /storage/sdcard0

meanwhile the actual external sd card should be:

/storage/extSdCard

The following are several posts regarding to this issues which may help you:

Building a Utility to get the path to External Removable storage every time

Check if the SDCard is present, boolean is always true

How could i get the correct external storage on Samsung and all other devices?

Android how to use Environment.getExternalStorageDirectory()