Storing Image Data

[Calum Maciver]

Hi,

I'm trying to permanently train a system to recognise a particular
image and associate it with an Integer. I've written a method that
compares images to see if they are already stored, and If they aren't
the user enters the number to be associated with the image. At the
moment I'm using HashMap<Integer,BufferedImage>. However this doesn't
store it permanently and I was wondering if there is an efficient way
of storing this data in a file so I can train the data and use it
repeatedly afterwards.