runtime - How to rename a file on sdcard with Android application?

Question

In my Android application, I want to rename the file name at runtime. How can I do it?

This is my code:

String[] command = {" mv", "sun moon.jpg"," sun_moon,jpg"};
try
{
    Process process = Runtime.getRuntime().exec(command);
} 
catch (IOException e)
{
    Toast.makeText(this, ""+e, Toast.LENGTH_LONG).show();
}

I also used renameTo(File f) method but it does not work.

Answer 1

I would recommend using File.renameTo() rather than running the mv command, since I'm fairly sure the latter isn't supported..

Have you given your application permission to write to the SD Card?

You do this by adding the following to your AndroidManifest.xml:

<uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE" />

If it doesn't work once the permission is added check the device log for errors when you try to rename the file (either using the adb command or in the logcat view in Eclipse).

When accessing the SD Card you shouldn't hard-code the path but instead use the Environment.getExternalStorageDirectory() method to get the directory.

The following code works for me:

File sdcard = Environment.getExternalStorageDirectory();
File from = new File(sdcard,"from.txt");
File to = new File(sdcard,"to.txt");
from.renameTo(to);

and if you want to check the process, you can do like:

boolean renamed = from.renameTo(to);

if (renamed) {
  Log.d("LOG","File renamed...");
}else {
  Log.d("LOG","File not renamed...");
}