Android :: Select Folder And Work Out When Intent Complete?

I am making a wallpaper and I want the user to select a folder. So I have a button in the preferences that launches an intent to open an image, but what I want is actually just a directory (I guess in the worst case I can strip the filename from the end). So thats my first problem. The second problem is how do I get notified of when the intent is complete?

public class FilePreference extends DialogPreference implements View.OnClickListener {
public void onClick(View v) {
// open up a gallery/file browser
Intent intent = new Intent();
intent.setType("image/*");
intent.setAction(Intent.ACTION_GET_CONTENT);
getContext().startActivity(Intent.createChooser(intent, "Select Folder"));
}