Mysterious IOException while writing a file

Question

This is the code I'm using to write a file .name to some folders in path /sdcard/ that with name starts with cimage. Currently I have 4 such folders, 2 of them were created lately. The problem is with these two and affects any folder that I manually add later.

public static void WriteName(ArrayList<String> citem) {
    final String not_writable = "norw";
    for (int i = 0; i < citem.size(); i++) {
        try {
            File root = new File(Environment.getExternalStorageDirectory()
                    .getName() + "/" + citem.get(i));
            File namefile = new File(root, ".name");
            FileReader namereader = new FileReader(namefile);
            BufferedReader in = new BufferedReader(namereader);
            String[] str_array = new String[4];
            str_array[0] = in.readLine();
            str_array[1] = in.readLine();
            str_array[2] = in.readLine();
            str_array[3] = in.readLine();
            Log.d("NameWrite", "line 4: " + str_array[3]);
            if (str_array[3] == null || !str_array[3].equals(not_writable)) {
                FileWriter namewriter = new FileWriter(namefile);
                BufferedWriter out = new BufferedWriter(namewriter);
                out.write(i
                        + "\nCImage_"
                        + (i)
                        + "\nAutogenerated Stub\nnorw\n");
                out.close();
            } else {
                Log.d("NameManager.WriteName", "Skipping " + root
                        + ", norw set");
            }
        } catch (IOException e) {
            Log.e("NameManager.java : ", ("Error!! Not Writable!!"
                    + Environment.getExternalStorageDirectory().getName()
                    + "/" + citem.get(i)));
        }
    }

}

So what happens is that when the method tries to write the last 2 folders it throws an IOException.

02-26 05:42:39.663: D/NameManager.java(5316): Checking for whatever
02-26 05:42:39.671: D/NameManager.java(5316): SDcard mounted RW
02-26 05:42:40.694: D/java.lang.java.lang.String(5316): file (43) :cimages
02-26 05:42:40.694: D/java.lang.java.lang.String(5316): file (76) :cimages_1
02-26 05:42:40.694: D/java.lang.java.lang.String(5316): file (77) :cimageslkj
02-26 05:42:40.694: D/java.lang.java.lang.String(5316): file (81) :cimages_2
02-26 05:42:40.694: D/NameWrite(5316): line 4: norw
02-26 05:42:40.694: D/NameManager.WriteName(5316): Skipping sdcard/cimages, norw set
02-26 05:42:40.702: D/NameWrite(5316): line 4: norw
02-26 05:42:40.702: D/NameManager.WriteName(5316): Skipping sdcard/cimages_1, norw set
02-26 05:42:40.702: E/NameManager.java :(5316): Error!! Not Writable!!sdcard/cimageslkj
02-26 05:42:40.710: E/NameManager.java :(5316): Error!! Not Writable!!sdcard/cimages_2
02-26 05:42:40.725: D/java.lang.java.lang.String(5316): file (77) :cimageslkj

I can find no explanation for this behavior. All other apps can write to those folder in case you are wondering. What might be causing this?

Use IOException.printStackTrace, or simply inspect available methods/properties in debug mode. http://stackoverflow.com/questions/8217500/how-to-print-stacktrace-for-an-exception-android — Tomas Voracek, Feb 26 '12 at 00:30
@TomasVoracek adding `e.printStackTrace();` don't give me any additional stack. — Binoy Babu, Feb 26 '12 at 00:34
@TomasVoracek It's file not found exception, thanks, I'll fix it. — Binoy Babu, Feb 26 '12 at 00:37
Just noticed one thing - you are not closing/disposing File, FileReader, BufferedReader objects in your try statement. It is always source of bugs like this. — Tomas Voracek, Feb 26 '12 at 00:57

score 1 · Answer 1 · edited May 23 '17 at 11:56

1

Use LogCat for error logging to console, see How to print stacktrace for an exception Android.

Also inspect stack trace, it has most useful info about error.

edited May 23 '17 at 11:56

Community

1
1

answered Feb 26 '12 at 00:39

Tomas Voracek

5,886
1
25
41

score 0 · Accepted Answer · answered Feb 26 '12 at 00:43

It's nothing mysterious, I just forgot to add a loop for cases in which .name don't exist. Adding this loop fixed it.

........
........
try {
                File root = new File(Environment.getExternalStorageDirectory()
                        .getName() + "/" + fsitem.get(i));
                File namefile = new File(root, ".name");
                if (!namefile.exists()){
                    namefile.createNewFile();
                }
                FileReader namereader = new FileReader(namefile);
                BufferedReader in = new BufferedReader(namereader);
                String[] str_array = new String[4];
........
........

Stephen C · Answer 3 · 2012-02-26T01:04:08.843

A large part of the problem is in this:

        } catch (IOException e) {
            Log.e("NameManager.java : ", ("Error!! Not Writable!!"
                + Environment.getExternalStorageDirectory().getName()
                + "/" + citem.get(i)));
        }

You are discarding all of the information in the IOException that you've caught, including the name of the actual exception and its message. It is Bad Practice to throw away basic exception information ... and you've been burned.

Best practice is to include the exception in the log by using the Log.e(tag, msg, throwable) overload.

Alternatively, if this was a "user mistake", you'd need to diagnose the problem and report it to the user. To do this, you'd probably need to catch relevant subtypes of IOException (e.g. FileNotFoundException) and tailor your end-user diagnostics and recovery accordingly.

Mysterious IOException while writing a file

3 Answers3