Question

I am trying to read a file from /data partition in Android. I wrote a test App and then started it on the emulator. Then I used “adb push local_path_to_file /data/mydir/file1” to copy file1 under /data/mydir/.

Now I tried the following in my App and nothing happens 🙁

How to read a file saved in the /data? What is wrong with my code?

Here is the snippet code:

            try {

            File source = new File(Environment.getExternalStorageDirectory().getAbsolutePath()+"/data/pu/file1");    
            InputStream is = new FileInputStream(source);
            String fileStr = new String(ReadBytesOfFile(is).toString);
            System.out.println("file out ="+ fileStr);
            is.close(); 
            }
            catch(IOException e){
                Log.d("file","NOT FOUND");
            }


         public byte [] ReadBytesOfFile (InputStream input) throws IOException {
            long length = input.available();
            byte[] rbuffer = new byte[(int) length];
            input.read(rbuffer);
            return rbuffer;
         }

Answer 1

First, you cannot store files in /data in production, except in the location returned to you by getFilesDir(), so you really need to rethink your approach.

Second, you are not trying to read from /data. Your code reads from a /data directory inside of Environment.getExternalStorageDirectory(). The precise location of Environment.getExternalStorageDirectory() varies by device and OS version, but /mnt/sdcard is the most common spot. Hence, you are presently trying to read from something like /mnt/sdcard/data, not /data.

Here is the documentation on data storage in Android.