Android: Cache XML File from RSS Feed

I just started doing my first Android app which happens to be an RSS Reader. I did a bit of googling about this but haven't seen a clear reference though. What I want to do is cache my xml file (the feed file) to the sdcard so when the phone is offline, the user can still view the feed by automatically telling the application to look for it when no network is detected. What I have now is the mechanism to cache the image but I wonder how to use this for other files since it was specified only for images that converts it to Bitmap using the HashMap().