How does appear saved SD card images in Android's Gallery?

I save an image to the sdcard and it doesn't appear in the Phone's Gallery. I can see saved image in a folder, but it folder doesn't apper in gallery.

My codes here, how fix it?

    img_icon.setOnLongClickListener(new View.OnLongClickListener() {

        @Override
        public boolean onLongClick(View v) {

            img_resim.buildDrawingCache();
            Bitmap bm = img_resim.getDrawingCache();

            OutputStream fOut = null;

            Uri outputFileUri;
            try {
                root = new File(Environment.getExternalStorageDirectory()
                        + File.separator + "folder_name" + File.separator);
                root.mkdirs();
                File sdImageMainDirectory = new File(root, "myPicName.jpg");
                outputFileUri = Uri.fromFile(sdImageMainDirectory);
                fOut = new FileOutputStream(sdImageMainDirectory);
            } catch (Exception e) {
                Toast.makeText(context.getActivity(),
                        "Error occured. Please try again later.",
                        Toast.LENGTH_SHORT).show();
            }

            try {
                bm.compress(Bitmap.CompressFormat.PNG, 100, fOut);
                fOut.flush();
                fOut.close();
            } catch (Exception e) {

            }

            context.getActivity()
                    .sendBroadcast(
                            new Intent(
                                    Intent.ACTION_MEDIA_SCANNER_SCAN_FILE,
                                    Uri.parse("file://"
                                            + Environment
                                                    .getExternalStoragePublicDirectory(Environment.DIRECTORY_PICTURES))));

            return true;
        }
    });

    return rowView;
}

Thanks for helping..

Solution

Your problem lies here:

context.getActivity()
                .sendBroadcast(
                        new Intent(
                                Intent.ACTION_MEDIA_SCANNER_SCAN_FILE,
                                Uri.parse("file://"
                                        + Environment
                                                .getExternalStoragePublicDirectory(Environment.DIRECTORY_PICTURES))));

You are asking Android to re-index all of the files in Environment.DIRECTORY_PICTURES.

Asking to scan a whole directory tree is wasteful. In your case, it it even more wasteful, since you are not writing your file to that directory. Instead, you are writing that file to:

root = new File(Environment.getExternalStorageDirectory()
                    + File.separator + "folder_name" + File.separator);
root.mkdirs();
File sdImageMainDirectory = new File(root, "myPicName.jpg");

Hence, your scan will not pick up this file, which you are writing to some random spot on external storage.

You need to decide the proper place to store your file, then index that one file.