String path = Environment.getExternalStorageDirectory().toString();
OutputStream fOut = null;
file = new File(path, "image.jpg");
fOut = new FileOutputStream(file);
Bitmap bitmap = BitmapFactory.decodeResource (getResources(), R.drawable.xyz);
bitmap.compress(Bitmap.CompressFormat.JPEG, 85, fOut);
fOut.flush();
fOut.close();
MediaStore.Images.Media.insertImage(getContentResolver(),file.getAbsolutePath(),file.getName(),file.getName());

String root = Environment.getExternalStorageDirectory().toString();
  File myDir = new File(root + "/saved_images");
  myDir.mkdirs();
  Random generator = new Random();
  int n = 10000;
  n = generator.nextInt(n);
  String fname = "Image-"+ n +".jpg";
  File file = new File (myDir, fname);
  if (file.exists ()) file.delete ();
  try {
       FileOutputStream out = new FileOutputStream(file);
       finalBitmap.compress(Bitmap.CompressFormat.JPEG, 90, out);
       out.flush();
       out.close();

} catch (Exception e) {
       e.printStackTrace();
}

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